Density Converter

Convert density between kg/m³, g/cm³, g/mL, kg/L, lb/ft³, lb/in³, oz per US gallon and slug/ft³. Every factor is exact by definition, derived from the SI meter and the 1959 international pound.

From

Value

lb/ft³

Result

16.0185 kg/m³

1 lb/ft³ = 16.018463 kg/m³

Decimals

All units

Unit	Value
Kilogram per cubic meter (kg/m³)	16.0185
Gram per cubic centimeter (g/cm³)	0.0160185
Gram per milliliter (g/mL)	0.0160185
Kilogram per liter (kg/L)	0.0160185
Pound per cubic foot (lb/ft³)	1
Pound per cubic inch (lb/in³)	5.78704E-4
Ounce per US gallon (oz/gal)	2.13889
Slug per cubic foot (slug/ft³)	0.031081

Need the density of flour, sugar or honey? The cooking converter carries 30 ingredients.

Updated: August 18, 2026

Density converter: kg/m³, g/cm³, g/mL, kg/L, lb/ft³ and slug/ft³.

Enter a density in kg/m³, g/cm³, g/mL, kg/L, lb/ft³, lb/in³, oz/gal or slug/ft³ and this converter returns it in every other unit on the list. The pair it handles most is lb/ft³ to kg/m³, where 1 lb/ft³ is 16.0185 kg/m³, and the three metric units come out identical because g/cm³, g/mL and kg/L all equal 1,000 kg/m³.

What Is a Density Converter?

Density is mass divided by volume, and its SI unit is the kilogram per cubic meter (kg/m³). A density converter takes a density you already know and rewrites it in another unit: 1 g/cm³ becomes 1,000 kg/m³, structural concrete at 2,400 kg/m³ becomes 149.827 lb/ft³, and sea-level air at 1.225 kg/m³ becomes 0.00237689 slug/ft³. Each of those pairs describes the same material; only the label changes. The arithmetic behind it is one multiplication and one division — multiply by the kg/m³ value of the unit you started in, divide by the kg/m³ value of the unit you want.

This page converts a density; it does not measure one. There is no mass field and no volume field, so a 250 g sample that displaces 32 cm³ needs the division done first — 250 ÷ 32 = 7.81 g/cm³ — and the result is what you bring here to move into lb/in³ or kg/m³. If the mass and the volume themselves are in awkward units, the mass converter and the volume converter sort those out before the division.

The eight units fall into three families, and the menus group them that way. The SI family holds kg/m³ alone, the coherent unit every other entry is measured against and the one that turns up in physics problems, CFD setups and metric datasheets. The metric working units are g/cm³, g/mL and kg/L, favored by chemists, geologists and 3D-printing hobbyists because ordinary solids and liquids land between 0.5 and 20 in them instead of in the thousands. The US customary family carries lb/ft³ for construction, concrete and HVAC air; lb/in³ for machining and stock weight; oz/gal for mixing and dosing; and slug/ft³ for US aerodynamics and fluid mechanics, where the mass unit has to be the slug if lift and drag are to come out in pounds-force.

g/cm³, g/mL and kg/L are one number written three ways. All three equal exactly 1,000 kg/m³, because a milliliter is a cubic centimeter and a liter is a cubic decimeter — the 12th General Conference on Weights and Measures settled the second half of that in 1964, when it made the liter a special name for the cubic decimeter. A filament quoted at 1.24 g/cm³ is 1.24 g/mL and 1.24 kg/L, and the Show all units table on this page prints those three rows with identical digits. A conversion table that lists all three side by side without saying so sends the reader hunting for arithmetic that does not exist.

Two close neighbors of density are worth keeping apart from it. Specific gravity, also called relative density, is a density divided by the density of water, which cancels the units away: steel at 7.85 g/cm³ has a specific gravity of 7.85, and the same steel at 490 lb/ft³ divided by water's 62.428 lb/ft³ gives 7.85 again. Specific weight is a force per unit volume rather than a mass per unit volume, so in US units water carries two figures at once: 1.940 slug/ft³ as a density, 62.4 lbf/ft³ as a specific weight. This converter works on mass per volume only.

How to Use the Density Converter

Pick the unit you are starting from in the From menu, type the number into Value, and pick the unit you want in the To menu — the result updates on every keystroke. On this US page the menus open on pound per cubic foot → kilogram per cubic meter, and Swap units flips the pair in one click. Both menus carry all eight units under their SI, Metric and US customary headers, so lb/ft³ to kg/m³, g/cm³ to lb/in³ and kg/L to oz/gal are each one selection away.

Decimals starts on Auto, which shows about six significant figures and drops trailing zeros; pin it to 0, 2, 4, 6, 10 or 15 when a spec demands a fixed number of places. Show all units opens a table of the same density in all eight units at once, with your target row highlighted — the fastest way to fill in a datasheet that wants both metric and US figures. The result copies to the clipboard in one tap, and the address bar rewrites itself as you type, so the URL already carries your from-unit, value, to-unit and precision: paste it into a report or a group chat and it reopens on the same conversion. The Value field refuses a minus sign, because a density is an amount of matter packed into a volume and cannot run negative.

By hand it is two steps, since every unit is pinned to the kilogram per cubic meter.

1. Multiply your value by its kg/m³ factor to reach the base unit.

2. Divide by the kg/m³ factor of the unit you want.

Mild steel at 7.85 g/cm³ into lb/in³ runs 7.85 × 1,000 = 7,850 kg/m³, then 7,850 ÷ 27,679.9 = 0.283599 lb/in³. Going the other way for an SI drawing, 62.4 lb/ft³ × 16.018463 = 999.552 kg/m³. The metric pairs collapse to a single power of ten — kg/m³ to g/cm³ is a division by 1,000 — and g/cm³ to g/mL is no arithmetic at all.

Common Density Conversions

Conversion	Result	Printed value
1 g/cm³	1,000 kg/m³	exact
1 g/mL	1,000 kg/m³	exact
1 kg/L	1,000 kg/m³	exact
1 kg/m³	0.001 g/cm³	exact
1 lb/ft³	16.0185 kg/m³	rounded
1 kg/m³	0.0624280 lb/ft³	rounded
1,000 kg/m³ (water, textbook value)	62.428 lb/ft³	rounded
1 lb/in³	27,679.9 kg/m³	rounded
1 lb/in³	27.6799 g/cm³	rounded
1 g/cm³	0.0361273 lb/in³	rounded
1 slug/ft³	515.379 kg/m³	rounded
1 kg/m³	0.00194032 slug/ft³	rounded
1 oz/gal (US)	7.48915 kg/m³	rounded
1 kg/m³	0.133526 oz/gal (US)	rounded

The Density Conversion Formula

\rho_{\text{target}} = \rho_{\text{source}} \times \dfrac{f_{\text{source}}}{f_{\text{target}}}

$\rho_{\text{source}}$ = The density you start from, in the source unit
$f_{\text{source}}$ = Kilograms per cubic meter in one source unit — 1,000 for g/cm³, g/mL and kg/L, 16.018463373960138 for lb/ft³
$f_{\text{target}}$ = Kilograms per cubic meter in one target unit
$\rho_{\text{target}}$ = The converted density, in the target unit

Every density conversion is one scaling up and one scaling down, because all density units share the same zero: an empty volume reads 0 in every one of them. Give each unit a single number — how many kilograms per cubic meter it equals — and any pair of units sits two multiplications apart. There is no offset to add, which is why lb/ft³ to kg/m³ behaves exactly like g/mL to slug/ft³.

The four US factors are built from definitions rather than measurements. A pound is 0.45359237 kg and a foot is 0.3048 m, both fixed exactly by the International Yard and Pound Agreement of 1959, so a cubic foot is 0.028316846592 m³ and 1 lb/ft³ works out to 0.45359237 ÷ 0.028316846592 = 16.018463 kg/m³. A cubic inch is 0.000016387064 m³, giving 1 lb/in³ = 27,679.9 kg/m³. The US liquid gallon is 231 cubic inches exactly, or 0.003785411784 m³, and an avoirdupois ounce is a sixteenth of a pound, so 1 oz/gal = 0.028349523125 ÷ 0.003785411784 = 7.489152 kg/m³. The slug is the US engineering mass unit, the mass that one pound-force accelerates at one foot per second squared: 1 slug = 1 lbf·s²/ft = 14.5939 kg = 32.174 lb, built on standard gravity g₀ = 9.80665 m/s², a value the 3rd General Conference fixed by convention in 1901. Divide that by a cubic foot and 1 slug/ft³ = 515.379 kg/m³.

NIST Special Publication 811, Appendix B.8 lists all four and prints its exact factors in boldface. None of the four density entries is bold there — pound per cubic foot appears as 1.601 846 E+01, pound per cubic inch as 2.767 990 E+04, ounce per US gallon as 7.489 152 E+00 and slug per cubic foot as 5.153 788 E+02, all in regular type, while the foot they are built from (3.048 E−01) appears in bold. Even the pound prints in regular type, because NIST shows 4.535 924 E−01 rather than the exact 0.453 592 37 kg it stands for. The reason is typographic rather than physical. Dividing an exact pound by an exact cubic foot leaves a fraction whose decimal expansion repeats forever, and a printed decimal can never show that exactly. The ratio is as fixed as the bold ones, so this converter tags all eight units exact and never labels a pair approximate.

The metric side needs no arithmetic at all. A gram in a cubic centimeter is a kilogram in a liter is a kilogram in a cubic decimeter, and since 1964 the liter has been a special name for the cubic decimeter, so g/cm³, g/mL and kg/L are the same 1,000 kg/m³ three times over. That same 1964 resolution advised against using the liter to report high-accuracy volume measurements, which is why metrology labs write cm³ and dm³ where a recipe or a spec sheet writes mL and L.

Worked Density Conversions

Water: 1 g/cm³, 1,000 kg/m³ and 62.428 lb/ft³

Enter 1 in g/cm³ and the converter returns 1,000 kg/m³, 1 g/mL, 1 kg/L and 62.428 lb/ft³ — the reference point most other densities get compared against. The tidy 1,000 is a legacy of the kilogram once being tied to a liter of water; the real maximum is 0.999975 g/mL, or 999.97 kg/m³, at 3.98 °C. Water thins as it warms: 998.2 kg/m³ at 20 °C and 997.0 kg/m³ at 25 °C. Convert that 997 and you get 62.2407 lb/ft³, about a fifth of a pound per cubic foot below the textbook 62.4, which is why any water figure quoted to four significant figures should carry the temperature it was taken at.

Machinist: mild steel at 7.85 g/cm³ in lb/in³

Steel stock is quoted as 7.85 g/cm³ in a metric shop and 0.284 lb/in³ in a US one, and they are the same steel: 7.85 g/cm³ converts to 0.283599 lb/in³, which is where the shop-floor 0.284 comes from. The same figure is about 490 lb/ft³. Once you have the lb/in³ value, multiply it by the volume of the billet in cubic inches to price and lift the stock before it arrives — a 2 in × 4 in × 12 in bar is 96 in³, so 96 × 0.283599 = 27.2 lb.

Aerospace: ISA sea-level air in slug/ft³

The ICAO International Standard Atmosphere puts sea-level air at 1.225 kg/m³, and the same air in US engineering units is 0.002377 slug/ft³. Convert 1.225 kg/m³ and this page returns 0.00237689 slug/ft³; feed the rounded 0.002377 back and you land on 1.22506 kg/m³, so the two published forms agree to within 0.005%. The slug is what makes the US form usable: with density in slug/ft³, speed in ft/s and area in ft², the dynamic pressure term ½ρV² comes out in pounds-force per square foot with no correction factor bolted on.

Construction and shop metals: 2,400 kg/m³ and 2.70 g/cm³ in lb/ft³

Structural concrete at 2,400 kg/m³ converts to 149.827 lb/ft³, so a 10 ft × 10 ft slab poured 4 in thick — 33.3 ft³ — weighs about 4,990 lb before you add rebar. Aluminum 6061 at 2.70 g/cm³ converts to 168.555 lb/ft³, roughly a third of steel's 490 lb/ft³, which is the entire argument for it in aerospace and bike frames. Both numbers are worth having in lb/ft³ rather than kg/m³ when the crane chart, the floor loading and the delivery ticket are all written in pounds.

3D printing: PLA filament at 1.24 g/cm³

PLA is 1.24 g/cm³, which the converter reads as 1,240 kg/m³, 1.24 g/mL and 1.24 kg/L — one material, four labels, one value. Slicing software stores the g/cm³ form — 1.24 is PrusaSlicer's PLA default — because it turns a print's volume into its weight: a 40 cm³ model uses 40 × 1.24 = 49.6 g of filament, and a 1 kg spool at that density holds about 806 cm³ of plastic. Wood-filled, metal-look and glow blends sit higher, so the same model can come off two spools weighing noticeably different amounts.

Dosing and mixing: 1 oz/gal in metric units

One ounce of powder per US gallon of water is 7.48915 kg/m³, which reads as 7.48915 grams per liter or 0.00748915 g/mL — the form a metric label or an EC chart expects. The unit is an avoirdupois ounce of substance per US liquid gallon of mixture, and the US gallon is 231 in³, or 3.785 L. An Imperial gallon is 4.546 L, so a British label reading 1 oz/gal describes a mix about 17% weaker than a US one at the same number. For ingredient densities by volume rather than dosing rates, the cooking converter carries a table of common ingredients in g/mL.

Common Density Conversion Mistakes

Dropping the factor of 1,000 between kg/m³ and g/cm³. Steel is 7.85 g/cm³ and 7,850 kg/m³; write 7.85 kg/m³ and you have described something a thousand times lighter than balsa. The slip is easy because both units are called "metric" and both look reasonable on a form. Fix the direction before you type: g/cm³ is the small number, kg/m³ is the big one, and everything between them is a single power of ten cubed.
Hunting for a conversion between g/cm³, g/mL and kg/L. There is none to find. All three equal 1,000 kg/m³, so a density of 0.891 in any one of them is 0.891 in the other two, and a table that shows all three rows carrying identical digits is behaving correctly. If a result looks suspicious because nothing changed, that is the definition of the liter and the milliliter doing its job.
Handing over a density when the form asked for specific gravity. Specific gravity is a density divided by water's, so it has no units at all: 7.85 g/cm³ of steel is a specific gravity of 7.85, and the same steel at 490 lb/ft³ divided by 62.428 lb/ft³ gives 7.85 again. Enter 7,850 into a field expecting 7.85 and every downstream figure moves by three orders of magnitude. This converter changes units and never divides by water, so do that step yourself.
Reading oz/gal as pounds per gallon. The oz/gal on this page is an avoirdupois ounce of substance per US liquid gallon, 7.48915 kg/m³ — a sixteenth of the lb/gal that drilling crews call ppg. Mixing them up inflates a dosing rate sixteenfold. The gallon matters too: the US gallon is 231 in³ or 3.785 L, while the Imperial gallon is 4.546 L, so the same printed rate means different concentrations on either side of the Atlantic.
Treating slug/ft³ as though the mass unit were the pound. A slug is 32.174 lb, so slug/ft³ figures are about 32 times smaller than the lb/ft³ ones sitting next to them: water is 1.940 slug/ft³ and 62.428 lb/ft³. Related and just as costly, the same water appears elsewhere as 62.4 lbf/ft³, which is a specific weight — force per volume — rather than a density. Check whether the column header says lb, lbf or slug before converting anything out of it.
Quoting a density without the temperature it was measured at. Water alone runs from 999.97 kg/m³ at 3.98 °C to 997.0 kg/m³ at 25 °C, and oils and polymers move considerably more than that across a working range. The conversion itself is exact, so any disagreement between your result and a published table at the fourth significant figure is almost always a temperature difference rather than a rounding error. Carry the temperature next to the number wherever the fourth figure matters.

Density Converter — Frequently Asked Questions

How do I convert kg/m³ to lb/ft³?

Divide the kg/m³ figure by 16.0185, or multiply it by 0.0624280. So 1,000 kg/m³ is 62.428 lb/ft³ and concrete at 2,400 kg/m³ is 149.827 lb/ft³. Reading back the other way, 1 lb/ft³ is 16.0185 kg/m³.

How do I convert g/cm³ to kg/m³?

Multiply by 1,000. Steel at 7.85 g/cm³ is 7,850 kg/m³ and PLA filament at 1.24 g/cm³ is 1,240 kg/m³. The factor is exact by definition, so nothing is lost in the step.

Is g/mL the same as g/cm³?

Yes, and kg/L is the same again. A milliliter is a cubic centimeter and a liter is a cubic decimeter, so all three units equal exactly 1,000 kg/m³. An oil at 0.891 g/mL is 0.891 g/cm³ and 0.891 kg/L with no arithmetic in between.

How many kg/m³ is 1 lb/ft³?

One pound per cubic foot is 16.0185 kg/m³. The factor falls out of the 1959 definitions: 0.45359237 kg divided by 0.028316846592 m³, the volume of a cubic foot.

What is the density of water in kg/m³ and lb/ft³?

Fresh water peaks at 999.97 kg/m³, or 62.426 lb/ft³, at 3.98 °C, which is where the round 1,000 kg/m³ used in textbooks comes from. It falls to 998.2 kg/m³ at 20 °C and 997.0 kg/m³ at 25 °C, the latter converting to 62.2407 lb/ft³. Seawater runs heavier, around 1,025 kg/m³ at the surface, because dissolved salts add mass without adding much volume.

How do I turn a density into specific gravity?

Divide by the density of water in the same units. In g/cm³ that division is invisible, since water is 1.000 — steel at 7.85 g/cm³ has a specific gravity of 7.85. In US units, divide by 62.428 lb/ft³: the same steel at 490 lb/ft³ gives 7.85 once more. Specific gravity carries no units, which is why it survives on datasheets that mix measurement systems. This converter changes units only and never performs that division for you.

What is a slug per cubic foot and when do I need it?

The slug is the US engineering mass unit — the mass that one pound-force accelerates at one foot per second squared, equal to 14.5939 kg or 32.174 lb. Density in slug/ft³ is what US aerodynamics and fluid mechanics use so that ½ρV² lands directly in pounds-force per square foot. Standard sea-level air is 0.002377 slug/ft³, which converts to 1.22506 kg/m³, and water is 1.940 slug/ft³.

Is oz/gal the same as lb/gal or ppg?

No. The oz/gal here is one avoirdupois ounce per US liquid gallon, 7.48915 kg/m³, the unit that appears on mixing, dosing and horticulture labels. The lb/gal that drilling crews call ppg is sixteen times larger and is not in this unit set. Confirm which one a label means before converting, because the two differ by a factor of 16.

Can this converter calculate density from mass and volume?

No — it converts a density you already have between units, so there is no mass field and no volume field. Do the division first: a 250 g sample filling 32 cm³ is 250 ÷ 32 = 7.81 g/cm³, and that figure is what you enter here to reach lb/in³ or kg/m³.

Why do g/cm³, g/mL and kg/L show the same number in the results table?

Because they are the same unit under three names. Since the 12th General Conference on Weights and Measures made the liter a special name for the cubic decimeter in 1964, a gram per milliliter, a gram per cubic centimeter and a kilogram per liter have all equaled exactly 1,000 kg/m³. The all-units table prints identical digits on those three rows on purpose.

How do I convert lb/in³ to g/cm³?

Multiply the lb/in³ value by 27.6799. Shop steel at 0.284 lb/in³ comes out at 7.86 g/cm³, and gold at 19.32 g/cm³ runs the other way to 0.697979 lb/in³. Because lb/in³ figures for metals are small decimals, keep at least three significant figures before converting or the metric result drifts in the second digit.

Does temperature change the density I should convert?

It changes the density, never the conversion. The factors on this page are fixed by definition, so 16.0185 kg/m³ per lb/ft³ holds at any temperature — but the material itself expands when heated, and water alone moves from 999.97 kg/m³ at 3.98 °C to 997.0 kg/m³ at 25 °C. Convert the figure that matches your working temperature, and quote that temperature alongside the result whenever the fourth significant figure is doing any work.

Will a material with my result float or sink?

A solid piece with no trapped air floats in fresh water below 1,000 kg/m³ — that is 1 g/cm³, or 62.428 lb/ft³ — and sinks above it. In seawater the line moves up to roughly 1,025 kg/m³. PLA at 1,240 kg/m³ sinks; oils, which sit below 950 kg/m³, float. Hollow or foamed shapes are settled by their average density, air pockets included, rather than by the density of the material they are cut from.

How accurate is this density converter?

Every one of the eight factors is exact by definition rather than measured. The metric units follow from the meter and the kilogram, and the four US units follow from the 1959 pound (0.45359237 kg), the international foot (0.3048 m), the 231 in³ gallon and standard gravity at 9.80665 m/s². They reproduce NIST Special Publication 811, Appendix B.8 to every digit NIST publishes, so any small difference you notice against another table is the display precision you picked, not the math.

Is this density converter free?

Yes — no account, no install, and it runs entirely in your browser. All eight units sit on one page, from kg/m³, g/cm³, g/mL and kg/L to lb/ft³, lb/in³, oz per US gallon and slug/ft³, so a metric datasheet and a US spec can be reconciled without opening a second tab. The same conversion is also reachable under the Density category of the general unit converter.

Can I embed this density converter on my site?

Yes. An ad-free embeddable version is available, so materials suppliers, engineering and machining blogs, 3D-printing guides and chemistry teaching pages can drop the converter in without loading third-party trackers.

Sources & References

Content verified by the Smart Calculators Team