Torque Converter

Convert between SI and imperial torque units (newton-metre, kilonewton-metre, kilogram-force metre, kilogram-force centimetre, pound-foot, pound-inch, ounce-inch) with NIST-grade exact factors anchored to CGPM 1901 standard gravity and the 1959 international yard and pound.

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From

Value

lb·ft

Result

1.35582 N·m

1 lb·ft= 1.355818 N·m

Decimals

All units

Unit	Value
Newton-meter (N·m)	1.35582
Kilonewton-meter (kN·m)	0.00135582
Kilogram-force meter (kgf·m)	0.138255
Kilogram-force centimeter (kgf·cm)	13.8255
Pound-foot (lb·ft)	1
Pound-inch (lb·in)	12
Ounce-inch (oz·in)	192

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Torque converter. SI, gravitational and US customary torque units with NIST-exact factors.

A torque converter changes a value from one unit of torque to another using exact NIST factors anchored to the SI newton-metre. So 1 lb·ft = 1.3558179483314003 N·m and 1 kgf·m = 9.80665 N·m exact, with every pair in the table tagged exact via the 1959 yard-and-pound and CGPM 1901 standard gravity.

What Is a Torque Converter?

A torque converter is a tool that takes a measurement in one unit of torque and returns the equivalent value in any other supported unit. Every conversion in this calculator routes through a single base unit, the newton-metre (N·m), using each unit's defined factor: 1 kilonewton-metre is exactly 1000 N·m, 1 kilogram-force metre is exactly 9.80665 N·m, 1 kilogram-force centimetre is exactly 0.0980665 N·m, 1 pound-foot is exactly 1.3558179483314003 N·m, 1 pound-inch is exactly 0.11298482902761668 N·m, and 1 ounce-inch is exactly 0.007061551814226043 N·m. These are not engineering approximations; they are exact rational products of three fixed values — the SI newton-metre (1 kg·m²/s² since the 2019 SI revision), the 1959 International Yard and Pound Agreement (1 lb = 0.45359237 kg exact, 1 ft = 0.3048 m exact, 1 in = 0.0254 m exact), and the 3rd CGPM (1901) declaration that standard gravity is exactly 9.80665 m/s².

The single most-important fact about a serious torque converter is the naming convention around lb·ft and ft·lb. They are the same unit of torque physically — one pound of force acting at a perpendicular distance of one foot from a pivot — but they are written in two different orders. The SI-preferred form is lb·ft (force first, then length), recommended by SAE and NIST so that the torque unit does not visually collide with ft·lb, which in physics and energy work refers to the foot-pound of work (the energy delivered when 1 lbf moves 1 ft along the line of action). Dimensionally lb·ft of torque and ft·lb of energy are identical (kg·m²/s²), but they describe different physical quantities — torque is a vector built from a cross product (τ = r × F), energy is a scalar built from a dot product. The same distinction holds in SI: 1 N·m of torque and 1 J of energy share base units but are deliberately kept apart in any well-written spec sheet. This converter labels every torque unit unambiguously and never uses "ft·lb" — when you see lb·ft here, it means torque.

This converter supports seven units across two families. The SI family (newton-metre, kilonewton-metre) dominates modern engineering specifications, every motor torque rating outside the US, every aerospace turbine bolt spec (wind-turbine tower joints now hit 12-15 kN·m), and physics literature. The gravitational family (kilogram-force metre, kilogram-force centimetre, pound-foot, pound-inch, ounce-inch) is the legacy of pre-SI engineering practice but is still standard in three living domains: US automotive and motorcycle service manuals (lb·ft and lb·in dominate every lug nut and spark plug spec sheet), Japanese and Taiwanese torque wrenches (Tohnichi, KTC and Snap-on Asia routinely publish in kgf·cm and kgf·m), and RC servo and small-motor datasheets (oz·in is the canonical small-torque rating). The most common everyday pair is N·m ↔ lb·ft for any cross-border automotive or motorcycle spec. All seven units in this calculator have exact rational factors and every pair is tagged exact.

What distinguishes a serious torque converter from a marketing widget is honesty about which factors are exact and how many digits matter. Most online converters print 1 lb·ft ≈ 1.3558 N·m (NIST SP 811 rounding) and stop there, dropping roughly 1.8 × 10⁻⁵ N·m of drift per lb·ft. This calculator exposes the full 1.3558179483314003 N·m, the exact IEEE-754 product of the NIST-exact rationals 4.4482216152605 (lbf) and 0.3048 (foot). The kilogram-force metre factor (9.80665, CGPM-1901-exact) is one of the cleanest in the table because no IYP cross-multiplication is involved. Every result here is tagged exact, the precision selector exposes up to 15 decimal digits (the full IEEE-754 double mantissa), and the display switches to scientific notation when results exceed 10¹² or fall below 10⁻³.

How to Convert Between Torque Units

Every torque conversion is one multiplication and one division through the newton-metre. The general formula is:

y = x \cdot \frac{a_{\text{from}}}{a_{\text{to}}}

where $x$ is your input value, $a_\text{from}$ is the source unit's factor to newton-metres, and $a_\text{to}$ is the target unit's factor to newton-metres. To do it by hand:

1. Look up the source-to-newton-metre factor. For pound-foot, $a_\text{from} = 1.3558179483314003$.

2. Multiply the input by that factor to get newton-metres. 100 lb·ft × 1.3558179483314003 = 135.58179483314 N·m.

3. Look up the target-to-newton-metre factor. For newton-metres, $a_\text{to} = 1$.

4. Divide the newton-metre value by the target factor. 135.58179483314 ÷ 1 = 135.58179483314 N·m.

The same procedure works for every supported unit. Going from kilogram-force metres to newton-metres: 1 kgf·m × 9.80665 N·m/(kgf·m) ÷ 1 N·m/N·m = 9.80665 N·m exact (the cleanest gravitational-to-SI conversion in the table, with the CGPM-1901 factor 9.80665 dropping out unchanged). Going from pound-inch to newton-metres: 1 lb·in × 0.11298482902761668 N·m/(lb·in) = 0.11298482902761668 N·m, which is exactly lb·ft ÷ 12 (because there are 12 inches in a foot). Going from ounce-inch to pound-inch: 1 oz·in × 0.007061551814226043 / 0.11298482902761668 = 0.0625 lb·in exactly (= 1/16, since there are 16 ounces in a pound, and the divisor 16 is a power of 2 that preserves bit-exactness in IEEE-754).

To use this calculator, pick the source unit from the "From" dropdown, type a value, then pick the target unit from the "To" dropdown. The result updates on every keystroke. Click the result card to copy it to the clipboard. Use the precision selector to switch between auto (6 significant figures), or a fixed 0, 2, 4, 6, 10 or 15 decimals. Auto-precision switches to scientific notation when the result is larger than 10¹² (one trillion) or smaller than 10⁻³, so converting a wind-turbine tower bolt spec (~15 kN·m → ~11 062 lb·ft → ~132 749 lb·in → ~2 124 000 oz·in) still renders readably at every step. The "exact" badge appears next to every torque result, because every unit in this set has a rational, definitionally exact factor to the newton-metre.

Torque Conversion Formula

y = x \cdot \frac{a_{\text{from}}}{a_{\text{to}}}

$y$ = The converted value, expressed in the target unit of torque.
$x$ = The input value, expressed in the source unit of torque.
$a_{\text{from}}$ = Factor that converts the source unit to newton-metres (e.g. 9.80665 for kgf·m, 1.3558179483314003 for lb·ft, 0.0980665 for kgf·cm).
$a_{\text{to}}$ = Factor that converts the target unit to newton-metres (e.g. 1000 for kN·m, 0.11298482902761668 for lb·in, 0.007061551814226043 for oz·in).

The formula is a two-step pivot through the newton-metre base unit. The factor table this calculator uses is sourced directly from NIST SP 811 Appendix B.8 (which lists kgf·m in boldface as exact at 9.80665, lb·ft at 1.355818, lb·in at 0.1129848 and ozf·in at 7.061552 × 10⁻³) and anchored to four exact upstream definitions — the SI newton-metre, the 1959 International Yard and Pound Agreement (1 lb = 0.45359237 kg, 1 ft = 0.3048 m, 1 in = 0.0254 m, all exact), and the 3rd CGPM (1901) declaration that g_n = 9.80665 m/s² exact:

Newton-metre (N·m): 1 N·m (exact, SI derived unit; 1 N·m ≡ 1 kg·m²/s²)
Kilonewton-metre (kN·m): 1000 N·m (exact, SI)
Kilogram-force metre (kgf·m): 9.80665 N·m (exact, = 1 kgf × 1 m; CGPM 1901 boldface in NIST SP 811)
Kilogram-force centimetre (kgf·cm): 0.0980665 N·m (exact, = kgf·m / 100)
Pound-foot (lb·ft): 1.3558179483314003 N·m (exact, = 4.4482216152605 N × 0.3048 m, IEEE-754 product of NIST exact rationals; NIST prints 1.355818 rounded)
Pound-inch (lb·in): 0.11298482902761668 N·m (exact, = lb·ft / 12 = 4.4482216152605 N × 0.0254 m; NIST prints 0.1129848 rounded)
Ounce-inch (oz·in): 0.007061551814226043 N·m (exact, = lb·in / 16 = (lbf/16) × in; the 16 is a power of 2, so the division is bit-exact in IEEE-754; NIST prints 7.061552e-3 rounded)

For the N·m → lb·ft direction the calculator displays the irrational quotient 1/1.3558179483314003 = 0.7375621492772656… lb·ft/N·m. Most casual converters print 0.7376 and stop there; this one will print as many digits as the precision selector requests, up to 15. The same applies to the N·m → lb·in ratio: 1/0.11298482902761668 = 8.8507457913272… lb·in/N·m (the constant every torque-screwdriver datasheet uses). Every result is tagged exact because both endpoints are exact rationals — the irrationality is in the printed form, not in the underlying definition.

Worked Torque Conversion Examples

100 lb·ft to N·m (the lug nut conversion every mechanic does)

Set From = Pound-foot, To = Newton-meter, Value = 100. The formula gives 100 × 1.3558179483314003 = 135.58179483314 N·m exact. At auto-precision the result reads 135.582 N·m (6 significant figures). A typical passenger-car lug nut spec lands in the 80–100 lb·ft window (108–135 N·m), with most Toyota Corolla-class sedans calling for 80 lb·ft = 108.47 N·m and Honda Accord-class mid-sizes calling for 100 lb·ft = 135.58 N·m. This is the conversion every US mechanic working on a Japanese-imported service manual does daily: the spec is written in N·m, the torque wrench is calibrated in lb·ft, and the result has to be exact because lug-nut over-tightening warps brake rotors. The 0.0006% gap between the casual 1.3558 rounding and the exact 1.3558179483314003 figure drifts by ~0.0018 N·m over 100 lb·ft — invisible on any wrench, but it accumulates.

1 kgf·m to N·m (the JDM service-manual conversion)

Set From = Kilogram-force meter, To = Newton-meter, Value = 1. The formula gives 1 × 9.80665 = 9.80665 N·m exact. This is the single cleanest gravitational-to-SI conversion in the whole table because the CGPM-1901 declaration fixes standard gravity at exactly 9.80665 m/s², no rounding involved. Older Japanese motorcycle service manuals (Honda CB-series, Yamaha FZ-series from the 1980s and 1990s) routinely specify cylinder-head bolts at 5.5 kgf·m = 53.94 N·m = 39.78 lb·ft and camshaft cap bolts at 1.6 kgf·m = 15.69 N·m = 11.57 lb·ft. The kgf·m unit survived in Asian and European technical literature long after BIPM deprecated it because workshop torque wrenches manufactured in Japan still ship with kgf·m and kgf·cm scales etched alongside N·m.

6 N·m to lb·in (the bicycle stem-bolt conversion)

Set From = Newton-meter, To = Pound-inch, Value = 6. The formula gives 6 / 0.11298482902761668 = 53.10 lb·in at auto-precision, more precisely 53.104474747963 lb·in at 12 decimals. A typical threadless bike stem steerer-clamp bolt (the bolt that holds your handlebar to the fork) spec'd by Shimano, Deda or FSA falls between 5 N·m and 8 N·m — too small for a click wrench calibrated in lb·ft, exactly the sweet spot for an inch-pound torque screwdriver. Park Tool publishes their bike-shop reference in N·m with an in-lb conversion column for exactly this reason. Over-tightening a carbon stem above ~8 N·m crushes the steerer tube; under-tightening lets the bar rotate in the clamp. The conversion is exact because both endpoints are exact rationals; the inch-pound wrench tolerance (typically ±4% per ISO 6789) is a much bigger error budget than any rounding of the conversion factor.

400 oz·in to N·m (the RC servo torque rating)

Set From = Ounce-inch, To = Newton-meter, Value = 400. The formula gives 400 × 0.007061551814226043 = 2.8246207256904 N·m exact, or about 2.82 N·m at auto-precision. A high-end standard-size hobby servo (Futaba, Hitec, JR) rated at "400 oz·in @ 6V" delivers roughly 2.82 N·m of holding torque — enough to drive a 1/8-scale RC car's steering linkage or a model aircraft's elevator under aerodynamic load. The oz·in unit dominates US-market RC servo datasheets, while Asian datasheets for the same servos quote the equivalent in kgf·cm: 400 oz·in × 0.007061551814226043 N·m/(oz·in) ÷ 0.0980665 N·m/(kgf·cm) = 28.80 kgf·cm, which is why hobby-grade specs almost always list both numbers side by side.

15 kN·m wind-turbine tower bolt to lb·ft (the kilonewton-metre scale)

Set From = Kilonewton-meter, To = Pound-foot, Value = 15. The formula gives 15 × 1000 / 1.3558179483314003 = 11 063.43 lb·ft at auto-precision. The latest offshore wind-turbine tower joints have torque targets climbing from the historical 5 kN·m (~3 690 lb·ft) limit to 12 kN·m (~8 851 lb·ft) and even 15 kN·m (~11 063 lb·ft) on the biggest 15-MW class machines. At this scale conventional click wrenches and torque multipliers cannot reach the spec; the work is done with hydraulic torque tensioners that pull the bolt directly. Wind turbine fasteners are typically Grade 10.9 or 12.9 high-tensile steel, and the difference between an under-torqued and a yielded bolt is a few percent on the spec sheet. The result is tagged exact because both endpoints (kN·m, lb·ft) are defined by exact rational factors.

Comparative table: 1 unit in newton-metres and pound-foot

Unit	Value in N·m	Value in lb·ft	Value in lb·in	Value in kgf·cm	Exact?
Ounce-inch (oz·in)	0.0070615518	0.0052083 (= 1/192)	0.0625 (= 1/16)	0.072007	yes
Kilogram-force cm (kgf·cm)	0.0980665	0.0723301	0.867962	1	yes
Pound-inch (lb·in)	0.1129848290	0.0833333 (= 1/12)	1	1.152124	yes
Newton-metre (N·m)	1	0.7375621493	8.8507458	10.19716	yes
Pound-foot (lb·ft)	1.3558179483	1	12	13.82550	yes
Kilogram-force m (kgf·m)	9.80665	7.233014	86.79617	100	yes
Kilonewton-metre (kN·m)	1000	737.5621493	8850.7458	10197.16	yes

Three definitional shortcuts worth memorising: 1 lb·ft = 12 lb·in exactly (the inch-per-foot ratio), 1 lb·in = 16 oz·in exactly (the ounce-per-pound ratio, both powers of 2 so bit-exact in IEEE-754), and 1 kgf·m = 100 kgf·cm exactly (the centimetre-per-metre ratio). All other rows are exact rationals that follow from these definitions and the SI newton-metre. The N·m ↔ lb·ft 1.3558179483 multiplier and its inverse 0.7375621493 are the two constants that crack the entire automotive cross-system.

Torque Conversion Tips

Treat 1 lb·ft ≈ 1.36 N·m as a back-of-envelope approximation only. The exact relationship is 1 lb·ft = 1.3558179483314003 N·m, the IEEE-754 product of the NIST-exact rationals 4.4482216152605 (pound-force, from IYP 1959 and CGPM 1901) and 0.3048 (foot, from IYP 1959). For mental conversions "multiply by 1.36" gets you within 0.3% (~0.4 N·m off on a 135 N·m lug nut). For service-manual, CAD or finite-element work, use the full factor and convert at the last step.
lb·ft is torque; ft·lb is energy. They are the same arithmetic product — pounds times feet — but they describe two different physical quantities. lb·ft (also written lbf·ft) is the torque applied by 1 pound-force at a perpendicular distance of 1 foot from the pivot. ft·lb (also written ft·lbf, foot-pound-force) is the energy delivered when 1 pound-force pushes an object along 1 foot of its line of action. NIST, SAE and BIPM all recommend the lb·ft order for torque (force first, then lever arm) precisely to keep the two visually separate. This calculator uses lb·ft throughout and never "ft·lb".
N·m and J have identical SI base units (kg·m²/s²) but are not interchangeable. The newton-metre is the torque unit; the joule is the energy unit. Torque is a vector built from a cross product (τ = r × F, perpendicular to both r and F by the right-hand rule); energy is a scalar built from a dot product (W = F · d). Spec sheets, FEA inputs and engineering drawings always keep them in their proper context — never write "50 J of torque" when you mean "50 N·m of torque", even though the arithmetic would look the same.
kgf·cm shows up on Japanese, Taiwanese and Korean torque wrenches. Tohnichi, KTC, Snap-on Asia and many Snap-on US precision torque drivers etch a kgf·cm scale alongside the N·m and lb·in scales because the kilogram-force centimetre remains standard in Asian small-fastener service manuals, robotics datasheets and servo specifications. 1 kgf·cm = 0.0980665 N·m exact = 0.86796 lb·in. A typical 100 kgf·cm precision driver covers about 9.81 N·m or 86.8 lb·in — the same range as a standard inch-pound bicycle wrench.
Memorise the four exact pivots through the newton-metre: kilonewton-metre (1000), kilogram-force metre (9.80665, CGPM-1901-exact), pound-foot (1.3558179483314003), and pound-inch (lb·ft / 12 = 0.11298482902761668). Every conversion in this tool is implemented as "input × from-factor ÷ to-factor", so memorising these four gives you the entire cross-table in your head. Kilogram-force centimetre (kgf·m / 100) and ounce-inch (lb·in / 16, both powers of 2 in the divisor) round out the set without introducing any new constants.
Click-style torque wrenches are typically rated to ±4% of indicated value (ISO 6789), and only between 20% and 100% of their full-scale range. A 100-lb·ft click wrench is reliable from 20 to 100 lb·ft and increasingly drifty below 20. The precision selector in this calculator targets spec-sheet conversion, not measurement: even at 15 decimals the converter is exact, but your wrench is not. For a lug nut spec of 100 lb·ft, the wrench's ±4% tolerance is ±4 lb·ft (±5.42 N·m) — orders of magnitude larger than any rounding error in the conversion. Calibrate the wrench every 5 000 cycles or 12 months per ISO 6789.
Every torque unit in this set is exact. Unlike length conversions involving the light-year or parsec, where IAU definitions exceed 64-bit double precision, every torque factor here is a finite rational that fits cleanly in IEEE-754: 1, 1000, 9.80665, 0.0980665, 1.3558179483314003, 0.11298482902761668, 0.007061551814226043 — all exact. The "exact" badge fires for every pair because the product of two exact rationals stays rational.
Use the precision selector to match your audience. Casual conversions round to 0–1 decimals (a Toyota lug-nut spec is just "108 N·m" in a workshop conversation). Service-manual writing typically quotes 2 decimals (108.47 N·m). High-precision aerospace and metrology work goes to 6–10 decimals because cumulative error over a thousand bolts on a wind-turbine flange shifts pre-load by margins that matter. Metrologists comparing against a primary torque standard want 15 decimals — the full IEEE-754 double mantissa exposed by this calculator. Switch precision at the model's last step to keep rounding error out of intermediate math.
When the result is larger than 10¹² (one trillion) or smaller than 10⁻³ at auto-precision, the display switches to scientific notation. This is on purpose: writing a 15 kN·m wind-turbine spec in ounce-inches as 2 124 053 oz·in is unreadable across systems, while 2.12e6 oz·in is parseable at a glance.
For automotive lug-nut and spark-plug specs, expect the spec sheet to mix units depending on the manufacturer's home market. US-built domestic vehicles spec in lb·ft ("100 ft-lbs" as the casual shop notation, even though lb·ft is technically correct). European and Korean OEMs spec in N·m. Japanese OEMs increasingly spec in N·m today but legacy service manuals are still in kgf·m. NGK spark-plug installation guidance ranges from 13 N·m (10 lb·ft) for small 10-mm plugs to about 30 N·m (22 lb·ft) for 14-mm gasket plugs in aluminium heads — always finger-tighten first, then torque to the spec value.

Torque Converter — Frequently Asked Questions

Is this torque converter free?

Yes. The calculator is free, requires no account, runs entirely in your browser, and is ad-free. The embeddable iframe version at /en-US/widget/torque-converter is also free and ad-free, so you can drop it into automotive workshops, motorcycle forums, bike-shop service pages, aerospace engineering portals or physics-education sites without exposing readers to third-party trackers.

How accurate are the torque conversion factors?

Every factor in this converter is exact. The newton-metre and kilonewton-metre are exact by SI definition. The kilogram-force metre is exact by CGPM-1901 standard gravity (9.80665 N per kgf × 1 m = 9.80665 N·m, printed in NIST SP 811 boldface as the canonical exact value). The pound-foot, pound-inch and ounce-inch are exact products of NIST-exact rationals: 1 lb·ft = 4.4482216152605 N × 0.3048 m = 1.3558179483314003 N·m, with zero rounding error. NIST prints rounded forms (1.355818, 0.1129848, 7.061552e-3), but every factor in this calculator is the full IEEE-754 product.

What is the difference between lb-ft and ft-lb?

Physically, when both refer to torque, lb·ft and ft·lb describe the same quantity: a pound of force acting at a 1-foot lever arm. The distinction is naming convention. SAE, NIST and BIPM recommend writing lb·ft (force first, then length) for torque, to keep it visually separate from the ft·lb (foot-pound) used as a unit of work or energy in physics. Dimensionally they share the same SI base units, but torque is a vector (cross product τ = r × F) while energy is a scalar (dot product W = F · d). In practice US service manuals, torque wrench markings and online converters interchange the two orderings freely, but the SAE-recommended order for torque is lb·ft.

Are newton-metre and joule the same?

Dimensionally yes; conceptually no. Both reduce to kg·m²/s² in SI base units. But the newton-metre is reserved for torque (rotational force, a vector) and the joule for energy or work (a scalar). The SI Brochure explicitly notes that "torque is not work and torque should be expressed in newton-metres, not joules". Writing 50 J of torque is wrong even though the arithmetic is identical to 50 N·m of torque — the unit signals what kind of quantity you are measuring.

How many N·m in 1 lb·ft?

Exactly 1.3558179483314003 N·m. The number is not measured; it is defined, as the product of 4.4482216152605 N (the exact pound-force from IYP 1959 and CGPM 1901) and 0.3048 m (the exact international foot from IYP 1959). Most casual references quote 1.3558 or 1.356, which are five- and four-significant-figure roundings. NIST SP 811 prints 1.355818 (seven significant figures), already an honest rounding. For metrology or aerospace work, use the full 17-digit IEEE-754 value.

How many lb·in in 1 lb·ft?

Exactly 12 lb·in. The relationship is purely geometric: 1 foot equals 12 inches by definition (IYP 1959, and centuries of customary use before that), so 1 pound-force × 1 foot = 1 pound-force × 12 inches = 12 lb·in exactly. Torque-screwdriver datasheets in the US use lb·in for small fasteners (electronics, bicycle stems, plumbing fittings) because lb·ft values smaller than ~1 are awkward to read on a wrench scale.

What is 1 kgf·m in newton-metres?

Exactly 9.80665 N·m. The CGPM-1901 declaration fixes standard gravity at exactly 9.80665 m/s², so 1 kilogram-force is exactly 9.80665 N and 1 kgf·m is exactly 9.80665 N·m. NIST SP 811 prints this factor in boldface as one of the cleanest gravitational-to-SI conversions in the entire torque section.

Why do Japanese torque wrenches use kgf·cm?

Because kgf·cm and kgf·m were the dominant Japanese industrial torque units before the BIPM SI revisions, and they survived in workshop practice long after BIPM deprecated them. Tohnichi, KTC and Snap-on KRA (the Asia-spec line) all ship click and dial torque wrenches with kgf·cm scales etched alongside N·m and lb·in. Asian servo and small-motor datasheets quote torque in kgf·cm or g·cm; Japanese motorcycle service manuals from the 1980s–1990s spec everything in kgf·m. 1 kgf·cm = 0.0980665 N·m exact = 0.86796 lb·in.

Is foot-pound the same as pound-foot?

Only when both are used to mean torque — and that is a convention, not a guarantee. The strict technical reading is that pound-foot (lb·ft) is the torque unit and foot-pound (ft·lb) is the unit of work or energy. Both use the same arithmetic (lbf × ft = 1.3558 N·m or J), but they describe different physical quantities. In a sentence like "the engine produces 300 ft-lb of torque", the ft-lb is being used in the loose sense and the SAE-correct version would be "300 lb-ft of torque". This calculator labels torque values in lb·ft throughout to keep the distinction sharp.

What is a typical lug nut torque in N·m and lb·ft?

Passenger cars typically call for 100–150 lb·ft (about 135–203 N·m), with compact sedans (Toyota Corolla, Honda Civic) near 80 lb·ft (108 N·m) and mid-size cars (Honda Accord, Toyota Camry) near 100 lb·ft (135 N·m). Light trucks and SUVs run higher, often 120–150 lb·ft (163–203 N·m). Always consult the owner's manual — aluminium wheels generally take ~10–15% less than steel wheels, and over-tightening warps brake rotors before it strips threads.

Why does 1 N·m to lb·ft give an irrational decimal?

Because the exact definition runs the other way: 1 lb·ft is exactly 1.3558179483314003 N·m. The inverse 1/1.3558179483314003 = 0.7375621492772656… lb·ft/N·m is mathematically irrational — there is no last digit, only a longer truncation. Engineering tables almost always print 0.7376; this calculator will show whatever precision you ask for, up to 15 decimal digits (the full IEEE-754 mantissa).

What unit do wind-turbine bolts use?

Modern offshore wind-turbine tower joints have torque targets in the 5 to 15 kN·m range (kilonewton-metres), with the largest 15-MW-class machines pushing past 12 kN·m on critical flange bolts. At that scale conventional click wrenches and hand torque multipliers are useless — the work is done with hydraulic torque tensioners that pull the bolt axially. 15 kN·m converts to about 11 063 lb·ft, 132 749 lb·in or 2 124 053 oz·in; the kN·m unit is the only one that stays readable at this scale.

Can I embed this torque converter on my site?

Yes. The embeddable version lives at /en-US/widget/torque-converter; copy the iframe snippet from the embed page. The iframe is ad-free, dependency-free, mobile-responsive, and inherits no third-party trackers — useful for automotive workshops, motorcycle and bicycle service portals, aerospace and wind-energy engineering blogs, and physics-education pages that need a converter without ad noise.

Key Torque Conversion Terms

Newton-metre (N·m)

The SI derived unit of torque, defined as 1 N·m ≡ 1 kg·m²/s² — the torque produced by 1 newton of force acting perpendicular to a 1-metre lever arm. Dimensionally equivalent to the joule but reserved for torque to keep rotational quantities distinct from energy. Standard for all modern scientific publishing, engineering specifications outside the US, and physics education. Wikidata: Q215571.

Kilonewton-metre (kN·m)

An SI unit of torque equal to exactly 1000 N·m. Used for large-bolt and structural torque specifications: wind-turbine tower joints (5–15 kN·m), ship propeller shafts, large-diameter flange connections in oil-and-gas equipment, and aerospace turbine attachment bolts. At this scale conventional hand wrenches are useless; the work is done with hydraulic torque tensioners.

Pound-foot (lb·ft)

A US customary and imperial unit of torque, equal to exactly 1.3558179483314003 N·m. Defined as the torque exerted by 1 pound-force (4.4482216152605 N exact, IYP 1959 + CGPM 1901) at a 1-foot lever arm (0.3048 m exact). The dominant unit in US automotive, motorcycle and aerospace torque specifications. SAE recommends lb·ft (force first) over ft·lb to keep it visually distinct from the foot-pound energy unit. Wikidata: Q16859309.

Pound-inch (lb·in, in·lb)

A US customary unit of torque equal to exactly 1/12 of a pound-foot = 0.11298482902761668 N·m. Standard for small-fastener torque in US service manuals: bicycle stem and seatpost bolts, electronics enclosure screws, instrument-panel fasteners, brake-system fittings, hard drive cases. Inch-pound torque screwdrivers and small click wrenches cover the 5–250 lb·in range that lb·ft wrenches cannot resolve accurately.

Ounce-inch (oz·in)

A US customary unit of torque equal to exactly 1/16 of a pound-inch = 0.007061551814226043 N·m. Because the divisor 16 is a power of 2, the conversion is bit-exact in IEEE-754 double-precision arithmetic. The canonical rating unit for hobby RC servos (a high-end standard servo is rated around 200–400 oz·in @ 6 V), micro-motors, precision-instrument springs and small dial torque indicators.

Kilogram-force metre (kgf·m, kp·m)

A non-SI unit of torque equal to exactly 9.80665 N·m — the torque produced by 1 kilogram of mass under standard gravity acting at a 1-metre lever arm. Listed in NIST SP 811 Appendix B.8 in boldface as exact. Standard in older European and Japanese automotive and motorcycle service manuals (Honda CB, Yamaha FZ, Suzuki GS series of the 1980s–1990s), and still common in Asian industrial torque specifications. Wikidata: Q216880 (parent unit kilogram-force).

Kilogram-force centimetre (kgf·cm)

A non-SI unit of torque equal to exactly 0.0980665 N·m = 1/100 of a kilogram-force metre. The dominant small-torque unit on Japanese, Taiwanese and Korean torque wrenches (Tohnichi, KTC, Snap-on Asia), Asian servo and small-motor datasheets, and Asian precision-fastener service manuals. A typical Tohnichi QL-series workshop wrench covers 4–2000 kgf·cm; the same range in N·m is roughly 0.4–196 N·m.

Torque vs energy distinction

Torque (N·m, lb·ft) and energy (J, ft·lb) share identical SI base units (kg·m²/s²) but describe different physical quantities. Torque is a vector built from the cross product τ = r × F, perpendicular to both the lever arm and the applied force by the right-hand rule. Energy is a scalar built from the dot product W = F · d, parallel to the displacement. The BIPM SI Brochure and SAE both insist torque and energy stay in their own unit lane: never write "50 J of torque" or "50 N·m of work".

lb·ft vs ft·lb naming

Two orderings of the same arithmetic product. SAE, NIST and BIPM recommend lb·ft (force first, lever arm second) for torque to keep it visually separate from ft·lb (foot-pound) used as an energy unit in physics and shock-wave engineering. British physicist Arthur Mason Worthington proposed the lb·ft form specifically to minimise this confusion. In practice US workshops and torque-wrench markings interchange the two orderings freely; this calculator uses lb·ft throughout.

Standard gravity (g_n)

The conventional gravitational acceleration on Earth's surface, fixed at exactly 9.80665 m/s² by the 3rd CGPM in 1901. Not a measured value at any particular point on Earth, but an exact defined constant that anchors every gravitational torque unit (kgf·m, kgf·cm, lb·ft, lb·in, oz·in) to the SI newton-metre. Wikidata: Q13400897.

Exact factor

A conversion factor fixed by international definition or international agreement, with zero rounding error. For torque, every factor in this calculator is exact: 1 kN·m = 1000 N·m, 1 kgf·m = 9.80665 N·m, 1 kgf·cm = 0.0980665 N·m, 1 lb·ft = 1.3558179483314003 N·m, 1 lb·in = lb·ft / 12, 1 oz·in = lb·in / 16. NIST SP 811 Appendix B.8 prints kgf·m in boldface as the canonical exact factor; lb·ft, lb·in and oz·in are exact products of NIST-exact upstream rationals.

International Yard and Pound Agreement (1959)

Multilateral agreement signed by the US, UK, Canada, Australia, New Zealand and South Africa, effective 1 July 1959. It defined the avoirdupois pound as exactly 0.45359237 kg, the international yard as exactly 0.9144 m, and the international foot as exactly 0.3048 m. Combined with CGPM-1901 standard gravity, this gives the exact pound-foot factor of 4.4482216152605 × 0.3048 = 1.3558179483314003 N·m.

Torque (τ)

The rotational counterpart of linear force, defined as the cross product of the position vector r and the force vector F: τ = r × F. ISQ dimension M·L²·T⁻² (the same as energy, but a vector instead of a scalar). Power follows P = τ · ω where ω is angular velocity. The recommended SI unit is the newton-metre. Wikidata: Q48103.

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