Force Converter

Convert between SI, gravitational, and CGS force units (newton, kilonewton, dyne, kilogram-force, tonne-force, pound-force, ounce-force, short-ton-force) with NIST-grade exact factors anchored to CGPM 1901 standard gravity.

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この計算機はまだ日本語に翻訳されていません。

翻訳作業中のため、英語版を表示しています。

From

Value

lbf

Result

4.44822 N

1 lbf= 4.448222 N

Decimals

All units

Unit	Value
Newton (N)	4.44822
Kilonewton (kN)	0.00444822
Dyne (dyn)	444,822
Kilogram-force (kgf)	0.453592
Tonne-force (tnf)	4.53592E-4
Ounce-force (ozf)	16
Pound-force (lbf)	1
Short ton-force (US) (tonf (US))	5E-4

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更新日: 2026年7月18日

Force converter: newtons, kgf, lbf, dyne and kN.

Enter a value in newtons, kilonewtons, pound-force, kilogram-force or dyne and this converter returns it in every other force unit through the newton. The distinction it hinges on is force versus mass: a kilogram-force is 9.80665 N and a pound-force is 4.44822 N, the weight of a kilo and a pound, not the matter itself.

What Is a Force Converter?

One kilogram-force is 9.80665 newtons, and one pound-force is 4.44822 newtons. Those two numbers exist because a "kilo" and a "pound" each name two different things: an amount of matter, and the push that matter makes when gravity pulls on it. Mass is how much stuff there is; force is a push or a pull. Keeping those two straight while it moves a value from one unit to another is the whole job of a force converter.

The bridge between the two worlds is gravity. Sit a 1 kg mass on Earth and it presses down with a force, and at standard gravity — g = 9.80665 m/s², a value fixed by convention rather than measured — that force is exactly 9.80665 N. Call that push the weight of a kilo and you have the kilogram-force. A pound works the same way: the weight of a one-pound mass is about 4.44822 N, and that is the pound-force. So kgf and lbf were invented so engineers could talk about "the weight of a kilo" or "the weight of a pound" without redoing the gravity step every time. The catch is that the tidy match only holds on Earth. Carry a 70 kg mass to the Moon and its mass is still 70 kg, but it now weighs only about 11.6 kgf, because lunar gravity is roughly a sixth of Earth's.

This converter routes every unit through one base — the newton (N), the SI unit of force, one kilogram accelerated at one meter per second squared. It handles three families. The SI family (newton, kilonewton) runs modern science and engineering. The gravitational family (kilogram-force, tonne-force, pound-force, ounce-force, short ton-force) is the pre-SI legacy still quoted on motor catalogs, hydraulic rams, press ratings and gym plates. The CGS family — the dyne — lingers in surface-tension figures and older physics work, where a single dyne is a minute 0.00001 N. The everyday anchors people actually search for drop straight out: 1 kgf is 9.80665 N, 1 lbf is 4.44822 N, and reading back the other way, 1 N is 0.224809 lbf.

How to Use the Force Converter

Pick your starting unit in the From menu, pick the unit you want in the To menu, and type the number — the result appears as you type and updates on every keystroke. Tap the result to copy it. Both menus hold the full list, so nothing is locked to a default pair: newtons to pounds, kgf to N, lbf to kN or dyne to newtons all behave the same way, and the precision control lets you pin the decimals when a figure runs long.

By hand it is two steps, because every unit is anchored to the newton. Multiply your value by its newton factor to reach newtons, then divide by the target unit's factor. Take 150 lbf into newtons: 150 × 4.44822 gives about 667.2 N. Going back to pounds for a US spec, 500 N ÷ 4.44822 — or 500 × 0.224809 — lands on about 112.4 lbf. Kilograms-force are the cleanest of all, because g is fixed: 1 kgf is 9.80665 N exactly, so a 200 kgf hydraulic ram is 200 × 9.80665 = 1961.33 N. The same two moves cover every unit in the list.

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The Force Conversion Formula

F_t = F_s × f_s ÷ f_t

$F_s$ = The force you start from, in the source unit
$f_s$ = Newtons in one source unit — its factor to the newton (9.80665 for kgf, 4.4482216152605 for lbf, 0.00001 for dyne)
$f_t$ = Newtons in one target unit — its factor to the newton
$F_t$ = The converted force, in the target unit

Every force unit descends from one equation: Newton's second law, force = mass × acceleration. One newton is what it takes to accelerate one kilogram at one meter per second squared, so 1 N = 1 kg·m/s². Once each unit is written as a number of newtons, converting between any two is a single multiplication, because all force units share the same zero — zero of anything is zero newtons. Give each unit its newton factor and any pair is two scalings apart: scale the input up to newtons with the source factor, then scale back down with the target factor. There is no offset to add, which is why kgf to N converts the same clean way as dyne to lbf.

The gravitational units come straight out of force = mass × acceleration with the acceleration set to standard gravity, g₀ = 9.80665 m/s² — a constant fixed by the 3rd CGPM in 1901 by convention, not measured at any one spot on Earth. A one-kilogram mass gives 1 × 9.80665 = 9.80665 N, which is one kilogram-force; a one-pound mass (0.45359237 kg) gives 0.45359237 × 9.80665 = 4.4482216 N, which is one pound-force. The dyne is the same law in CGS units: one gram accelerated at one centimeter per second squared is 0.001 kg × 0.01 m/s² = 0.00001 N.

Every conversion factor in this set is an exact definition — there are no measured or approximate factors here, unlike some pressure units (torr, mmHg) that rest on a never-ending quotient. Newton, kilonewton, kilogram-force, tonne-force and dyne are exact by declaration, and pound-force, ounce-force and short ton-force are exact products of the exact pound and the exact g₀. What the reference table marks "rounded" is only the displayed decimal — 4.44822 shown for the exact 4.4482216152605, or 0.224809 shown for the non-terminating 1 ÷ 4.4482216152605 — not the factor behind it. Raise the precision and the hidden digits are already there.

Common Force Conversions

Conversion	Result	Exact?
1 kilogram-force (kgf)	9.80665 N	exact
1 pound-force (lbf)	4.44822 N	rounded
1 newton (N)	0.224809 lbf	rounded
1 newton (N)	0.101972 kgf	rounded
1 kilonewton (kN)	1000 N	exact
1 kilonewton (kN)	224.809 lbf	rounded
1 dyne	0.00001 N	exact
1 tonne-force	9806.65 N	exact
1 tonne-force	9.80665 kN	exact
1 pound-force (lbf)	0.453592 kgf	rounded
1 ounce-force (ozf)	0.278014 N	rounded
1 short ton-force	8896.44 N	rounded

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Worked Force Conversions

Hydraulic ram: 80 kgf in newtons

A hydraulic ram or spring rated at 80 kgf pushes with 784.53 N. Multiply kilograms-force by 9.80665, the exact standard-gravity factor: 80 × 9.80665 = 784.532 N. Because g₀ is fixed by definition, this step carries no rounding error — the only reason the answer is not a round number is the ram's own 80 rating. To quote the same load on an SI datasheet you would write 0.785 kN, and to check it against a US spec, 784.532 ÷ 4.44822 = 176.4 lbf.

US fastener: 250 lbf clamp load in newtons

A bolt torqued to a 250 lbf clamp load holds 1112.06 N. Multiply pound-force by 4.44822: 250 × 4.44822 = 1112.06 N, which rounds to 1.11 kN on an SI drawing. The reverse divides by the same factor, so a 900 N spec is 900 ÷ 4.44822 = 202.3 lbf. Note this is pound-force — the clamping push — not the pound-mass a scale would read for the parts being clamped; the two only share a number at Earth's surface.

Winch pull: 2000 N in pounds-force and kilograms-force

A winch rated at 2000 N delivers 449.62 lbf or 203.94 kgf. For pounds-force, multiply by 0.224809 (or divide by 4.44822): 2000 × 0.224809 = 449.62 lbf. For kilograms-force, multiply by 0.101972 (or divide by 9.80665): 2000 × 0.101972 = 203.94 kgf. So a 2 kN winch, a 450 lbf winch and a 204 kgf winch are three labels for the same pull — useful when a US catalog and a legacy kgf datasheet describe the same drum.

Crane rating: 100 kN in tonne-force and pounds-force

A crane hook rated at 100 kN can hold 10.20 tonne-force or 22,481 lbf. Divide by 9.80665 for tonne-force — 100 ÷ 9.80665 = 10.197, since 1 tonne-force is 9.80665 kN — and multiply the 100,000 N by 0.224809 for pounds-force: 100,000 × 0.224809 = 22,481 lbf. That 10.2 tonne-force reading is why cranes and lifting gear are still catalogued in tonne-force across much of industry, even though the structural math behind them runs in kilonewtons.

Small forces and CGS: 16 ozf in newtons and dyne

Sixteen ounce-force is exactly one pound-force — 4.44822 N — because an ounce-force is defined as one-sixteenth of a pound-force. Multiply ounce-force by 0.278014: 16 × 0.278014 = 4.44822 N. The same push in CGS units is 444,822 dyne, since 1 N is 100,000 dyne (4.44822 × 100,000). Ounce-force is the unit for small pushes — spring tension, tape peel, keypad actuation — while the dyne, at just 0.00001 N each, survives in surface-tension figures and older physics texts.

Common Force Conversion Mistakes

Reading kilogram-force as kilograms of mass. This is the one that bites hardest. A kilogram (kg) measures how much matter there is; a kilogram-force (kgf) measures the push that matter makes under gravity. They are different quantities that only line up numerically on Earth, where 1 kg of mass weighs 9.80665 N, or 1 kgf. Drop the factor of g = 9.80665 and a force comes out roughly ten times too small, so never hand a value in kgf to a spec that wants newtons without multiplying it through.
Mixing pound-force with pound-mass. The same trap in imperial dress: pound-force (lbf) is a push, while pound-mass (lb) is an amount of matter. The "50 lb" on a luggage scale is mass; "50 lbf" of clamping load on a fixture is force. They match in number only at Earth's surface, where a 1 lb mass weighs 1 lbf, which is 4.44822 N. In any problem with acceleration, keep force and mass in separate columns.
Assuming a scale's number is already in newtons. A bathroom or kitchen scale reads force, but it shows a mass label after dividing by a built-in gravity value, so the quantity behind "70 kg" is really 70 kgf. Do not carry that 70 straight into a newton field: 70 kgf is 70 × 9.80665 = about 686 N, not 70 N. The newton and the kilogram-force differ by nearly a factor of ten, and swapping them one-for-one is a common data-entry slip.
Rounding standard gravity to 9.81. The kilogram-force and tonne-force are tied to g₀ = 9.80665 m/s² exactly, not the classroom 9.81. The gap is small — about 342 parts per million (0.034%) — but on a 500-tonne-force press it is roughly 1,675 N, enough to matter on a calibration certificate. Use the full 9.80665 whenever the result feeds a spec rather than a rough estimate.
Forgetting how small a dyne is. The dyne is a CGS unit and it is minute — 1 dyne is only 0.00001 N (1 × 10⁻⁵ N), or 10 micronewtons. It turns up in surface-tension figures and older physics texts, so a value that looks big in dynes is tiny in SI: 100,000 dyne is just 1 N. When a result seems off by five orders of magnitude, a stray dyne-to-newton step is usually the reason.

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Force Converter — Frequently Asked Questions

How many newtons are in a pound-force?

One pound-force is 4.44822 newtons. It is the weight of a one-pound mass at standard gravity: 0.453592 kg × 9.80665 m/s². Rounded references often print 4.448 N, but 4.44822 keeps enough digits for engineering work.

How many newtons is 1 kgf?

One kilogram-force is exactly 9.80665 newtons, the weight of a one-kilogram mass at standard gravity. To convert any kgf figure, multiply by 9.80665: 10 kgf is 98.07 N and 100 kgf is 980.665 N. The factor never drifts, because g is fixed by definition.

What is the difference between kg and kgf?

A kilogram (kg) is mass, the amount of matter in an object; a kilogram-force (kgf) is the weight that mass has under gravity, equal to 9.80665 N. A 70 kg person has 70 kg of mass anywhere in the universe, but weighs about 70 kgf only on Earth — and roughly 11.6 kgf on the Moon.

Is 1 kgf the same as 1 N?

No. One kilogram-force is 9.80665 newtons, almost ten times larger than a single newton. Both are force units, but a scale reading of 70 kgf is about 686 N, not 70 N.

What is the difference between lbf and lb?

Pound-force (lbf) is a push or pull; pound-mass (lb) is an amount of matter. One lbf is 4.44822 N, and one lb is 0.453592 kg. They match in number only at Earth's surface, where a 1 lb mass weighs 1 lbf. In any calculation involving acceleration, keep the two apart.

How do I convert newtons to pounds of force?

Multiply the newton value by 0.224809, or divide it by 4.44822. So 500 N is about 112.4 lbf and 1000 N is about 224.8 lbf. Reading the other way, 1 lbf is 4.44822 N.

How do I convert kgf to newtons?

Multiply by 9.80665, the exact standard-gravity factor. So 1 kgf is 9.80665 N, 100 kgf is 980.665 N, and a 5-tonne-force press exerts 5 × 9806.65 = 49,033 N. Because g is fixed by definition, this conversion carries no rounding error.

How do I convert tonne-force to kilonewtons?

Multiply tonne-force by 9.80665, since 1 tonne-force is 9806.65 N, or 9.80665 kN. So a 5-tonne-force press is 5 × 9.80665 = 49.03 kN, and a 100-tonne-force machine is 980.67 kN. One tonne-force is exactly 1000 kgf, so it uses the same 9.80665 factor as kilograms-force.

Why is standard gravity fixed at 9.80665 m/s²?

Because it is a convention, not a local measurement. Real gravity varies across the Earth's surface — a little weaker near the equator, a little stronger near the poles — so a single value was set by international agreement to tie kilogram-force and pound-force to the newton. That is why 1 kgf equals exactly 9.80665 N and never drifts.

What is a dyne and how big is it?

A dyne is the CGS unit of force, and it is minute: 1 dyne is 0.00001 N, or 10 micronewtons. It survives mainly in surface-tension measurements and older physics texts. In SI terms, 100,000 dyne make just one newton.

My scale shows 70 kg — how much force is that in newtons?

About 686 newtons. A scale reads force but labels it as mass, so 70 "kg" is really 70 kgf, and 70 × 9.80665 = 686.47 N. When a spec asks for the load in newtons, use that 686 N figure, not the raw 70.

How accurate is this force converter?

The factors are the defined standards: 1 kgf is exactly 9.80665 N, 1 dyne is exactly 0.00001 N, and 1 lbf is 4.44822 N (from 0.453592 kg × 9.80665 m/s²). The SI and gravitational units are fixed by definition, so any tiny differences you notice come from the display precision you pick, not the math.

Is this force converter free?

Yes — no account, no install, and it runs entirely in your browser. Every force unit sits on one page, from newton, kilonewton and dyne to kilogram-force, tonne-force, pound-force, ounce-force and short ton-force, so you can move between an SI datasheet and a US thrust rating in one place.

Can I embed this force converter on my site?

Yes. An ad-free embeddable version is available, so engineering portals, aerospace and physics blogs, hydraulic-equipment catalogs and STEM-teaching pages can drop the converter in without loading third-party trackers.

出典・参考文献

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