Density Calculator

Solve density, mass or volume from the other two, with 121 sourced material densities, relative density, a float-or-sink verdict and the working shown step by step.

Density Mass Volume

Mass

Mass unit

Volume

Volume unit

Density unit

Significant figures

Auto keeps about six significant figures.

Density

2.5 g/cm³

2,500 kg/m³ in SI units

Relative density

2.50006

against water at 4 °C

In water

Sinks

Closest material

Graphite

2,500 kg/m³, 0% from yours

ρ = 250 g ÷ 100 cm³ = 2.5 g/cm³

Volume from a shape

Know the shape but not the volume? Give its dimensions and the volume is worked out for you.

Shape

The working, step by step

Step	Value
Mass in SI	0.25 kg
Volume in SI	1 × 10⁻⁴ m³
Density = mass ÷ volume	2,500 kg/m³
In your chosen unit	2.5 g/cm³

Both given values are converted to SI first, which is where the unit mistakes happen.

Your answer in other units

Unit	Value
kg/m³	2,500
g/cm³	2.5
g/mL	2.5
kg/L	2.5
lb/ft³	156.07
lb/in³	0.0903182
oz/gal (US)	333.816
slug/ft³	4.8508
g/L	2,500

The same answer, expressed in each unit of its own kind.

Material density reference

Material	kg/m³	Range	Source
Hydrogen (H₂)	0.0837523		NIST Chemistry WebBook
Helium (He)	0.166311		NIST Chemistry WebBook
Methane (CH₄)	0.66816		NIST Chemistry WebBook
Nitrogen (N₂)	1.16483		NIST Chemistry WebBook
Air (dry)	1.205		NIST (compounds)
Oxygen (O₂)	1.33118		NIST Chemistry WebBook
Argon (Ar)	1.66182		NIST Chemistry WebBook
Carbon dioxide (CO₂)	1.83934		NIST Chemistry WebBook
Propane (C₃H₈)	1.86499		NIST Chemistry WebBook
Glass wool	25		Engineering reference
Snow (fresh)	100		Engineering reference
Balsa	125	110–140	Engineering reference
Rubber foam	155	60–250	Engineering reference
Cork	225	200–250	Engineering reference
Bamboo	355	310–400	Engineering reference
Pine (yellow)	420		Engineering reference
Pine (white)	425	350–500	Engineering reference
Cedar	530	490–570	Engineering reference
Lithium	534		NIST (elements)
Spruce	630	480–780	Engineering reference
Birch	640	510–770	Engineering reference
Walnut	670	640–700	Engineering reference
Mahogany	675	500–850	Engineering reference
Maple	685	620–750	Engineering reference
Concrete (lightweight)	725	450–1,000	Engineering reference
Gasoline (petrol)	737		Engineering reference
Oak	750	600–900	Engineering reference
Ash (white)	750	650–850	Engineering reference
Cherry	765	630–900	Engineering reference
Acetone	784.6		Engineering reference
Ethanol	789		Engineering reference
Methanol	791.01		NIST Chemistry WebBook
Beech	800	700–900	Engineering reference
Plasterboard (drywall)	800		Engineering reference
Teak	820	660–980	Engineering reference
Kerosene (paraffin)	820.1		Engineering reference
Turpentine	870		Engineering reference
Benzene	873.8		Engineering reference
Diesel fuel	885	820–950	Engineering reference
Motor oil	900		Engineering reference
Olive oil	911		Engineering reference
Ice	917		Engineering reference
Rubber (pure gum)	920	910–930	Engineering reference
Paper	925	700–1,150	Engineering reference
Polyethylene (PE)	930		NIST (compounds)
Body fat	950		NIST (compounds)
Sodium	971		NIST (elements)
Water	998.21		NIST Chemistry WebBook
Seawater	1,025		Engineering reference
Milk	1,035	1,020–1,050	Engineering reference
Muscle	1,050		NIST (compounds)
Polystyrene (PS)	1,060		NIST (compounds)
Human body (soft tissue)	1,060		NIST (compounds)
Blood	1,060		NIST (compounds)
Acrylic (PMMA)	1,190		NIST (compounds)
Rubber (hard)	1,200		Engineering reference
Ebony	1,220	1,110–1,330	Engineering reference
Glycerin	1,249		Engineering reference
Bakelite	1,250		NIST (compounds)
Coal (bituminous)	1,350	1,200–1,500	Engineering reference
PET (Mylar)	1,380		NIST (compounds)
PVC	1,406		NIST (compounds)
Cement (Portland, loose)	1,500		Engineering reference
Sand (dry)	1,500	1,400–1,600	Engineering reference
Calcium	1,550		NIST (elements)
Coal (anthracite)	1,600	1,400–1,800	Engineering reference
Magnesium	1,740		NIST (elements)
Sealing wax	1,800		Engineering reference
Beryllium	1,848		NIST (elements)
Brick (common)	1,900	1,400–2,400	Engineering reference
Bone (cortical)	1,920		NIST (compounds)
Soil	2,050		Engineering reference
Clay	2,200	1,800–2,600	Engineering reference
Glass (borosilicate / Pyrex)	2,230		NIST (compounds)
PTFE (Teflon)	2,250		NIST (compounds)
Sandstone	2,250	2,100–2,400	Engineering reference
Concrete (ordinary)	2,300		NIST (compounds)
Firebrick	2,300		Engineering reference
Silicon	2,330		NIST (elements)
Chalk	2,350	1,900–2,800	Engineering reference
Asphalt (compacted)	2,360		Engineering reference
Graphite	2,500	2,300–2,700	Engineering reference
Glass (common)	2,600	2,400–2,800	Engineering reference
Quartz	2,650		Engineering reference
Aluminum	2,699		NIST (elements)
Granite	2,700	2,600–2,800	Engineering reference
Marble	2,700	2,600–2,800	Engineering reference
Limestone	2,750	2,700–2,800	Engineering reference
Basalt	2,750	2,400–3,100	Engineering reference
Duralumin	2,790		Engineering reference
Slate	2,950	2,600–3,300	Engineering reference
Diamond	3,250	3,000–3,500	Engineering reference
Titanium	4,540		NIST (elements)
Glass (lead)	6,220		NIST (compounds)
Zinc	7,133		NIST (elements)
Chromium	7,180		NIST (elements)
Cast iron	7,300	6,800–7,800	Engineering reference
Tin	7,310		NIST (elements)
Manganese	7,440		NIST (elements)
Stainless steel	7,740	7,480–8,000	Engineering reference
Wrought iron	7,750		Engineering reference
Steel (carbon)	7,850		Engineering reference
Iron	7,874		NIST (elements)
Bronze	8,150	7,400–8,900	Engineering reference
Inconel	8,497		Engineering reference
Brass	8,550	8,400–8,700	Engineering reference
Monel	8,600	8,360–8,840	Engineering reference
Solder (50/50 Pb-Sn)	8,885		Engineering reference
Cobalt	8,900		NIST (elements)
Nickel	8,902		NIST (elements)
Copper	8,960		NIST (elements)
Molybdenum	10,220		NIST (elements)
Silver	10,500		NIST (elements)
Lead	11,350		NIST (elements)
Mercury	13,550		NIST (elements)
Uranium	18,950		NIST (elements)
Tungsten	19,300		NIST (elements)
Gold	19,320		NIST (elements)
Platinum	21,450		NIST (elements)
Iridium	22,420		NIST (elements)
Osmium	22,570		NIST (elements)

Values from NIST are single-valued constants at a stated condition. Alloys, woods, rocks and aggregates are published as a span, and the figure shown is its midpoint.

What changes a density

Density falls as temperature rises, because the same mass takes up more room. For solids the change is small — under a tenth of a percent over normal room temperatures — and liquids move rather more: water shifts about 0.1% over five degrees, ethanol nearly ten times that. Water is the famous exception: it is densest near 4 °C, not at freezing, which is why lakes ice over from the top.

A gas has no single density. Every gas figure here is quoted at 20 °C and 101.325 kPa; the same gas at 0 °C is about 7% denser, which is the number most tables print without saying which one it is.

A powder, a soil or an aggregate measured by the space it fills gives BULK density, not the density of the material itself — the voids between the grains are counted as if they were solid. The two differ by a third or more for dry sand.

Already have a density and just need it in other units? Open the density conversion tool.

Updated: August 19, 2026

Density calculator. Density, mass or volume from the other two.

A density calculator divides mass by volume: 250 grams filling 100 cm³ is 2.5 g/cm³, or 2,500 kg/m³. Give it any two of density, mass and volume — or pick a material such as steel or oak and let it fill the density in — and it returns the third with the working shown.

What Is Density?

Density is the amount of mass packed into a given amount of space: mass divided by volume, written ρ = m ÷ V. Its SI unit is the kilogram per cubic meter (kg/m³), and the everyday laboratory unit is the gram per cubic centimeter (g/cm³), which is exactly 1,000 times larger. Fresh water is 998.21 kg/m³ at 20 °C, carbon steel is 7,850 kg/m³, dry air is 1.205 kg/m³, and osmium — the densest entry in this calculator's table — is 22,570 kg/m³. From hydrogen at 0.0838 kg/m³ up to that osmium figure is a span of more than five orders of magnitude, which is why the unit attached to a density matters as much as the digits in front of it.

This page solves the relation in all three directions. Give it mass and volume and it returns density; give it a density and a volume and it returns mass; give it a density and a mass and it returns volume. Every field carries its own unit menu, so grams can meet cubic inches and pounds can meet liters without you doing the dimensional analysis by hand — the step where density homework goes wrong.

You do not have to know the density to start. A filterable list of 121 materials in eight groups — metals and alloys, liquids, gases, woods, building and construction, plastics and polymers, rocks, minerals and earth, and everyday materials — fills the density field for you. Fifty-two of those values are traceable to NIST tables and the other 69 to engineering references, and every row in the reference table below the calculator names its own source. Forty-two entries are published as a range instead of a single number, because a "density of oak" is a span: the picker fills the midpoint and says on screen what the span was, so you can narrow it to the piece in front of you.

The page also tells you what your number means. Relative density — specific gravity — divides your result by water at its densest, 999.975 kg/m³ near 4 °C, so 7,850 kg/m³ of steel reads 7.850, a dimensionless figure that survives any change of units. A gas is compared against dry air at 1.205 kg/m³ instead. The float card applies Archimedes' principle: anything below water's density floats, and for a floater it reports how much of it sits below the surface. Ice at 917 kg/m³ floats with 91.7% submerged in fresh water, and body fat at 950 kg/m³ floats while muscle at 1,050 kg/m³ sinks, which is the whole physics of why lean swimmers ride low.

Two things this page deliberately does not do. It takes no temperature and no pressure as an input: the stored material values carry their stated condition instead, with every gas quoted at 20 °C and 101.325 kPa. And it is not a unit converter — it computes a density rather than restating one you already have. If you already have a figure and only need it written in another unit, the density converter is built for that.

How to Calculate Density from Mass and Volume

To calculate density, divide the mass of the object by its volume. The arithmetic is one division; the care goes into the units, and into measuring the volume of anything that is not a neat block.

1. Weigh the object and note the unit — grams for a lab sample, kilograms or pounds for a beam or a casting.

2. Find its volume. A regular shape can be measured and multiplied out; an irregular one is measured by displacement.

3. Divide mass by volume, keeping the two in units that pair: grams with cubic centimeters gives g/cm³, kilograms with cubic meters gives kg/m³.

4. Restate the answer in the unit your report or spec asks for — 1 g/cm³ is exactly 1,000 kg/m³.

On this page those four steps collapse into typing two numbers. Leave the mode on Density, enter the mass with its unit, enter the volume with its unit, and the answer appears with the substitution written underneath: ρ = 250 g ÷ 100 cm³ = 2.5 g/cm³. Switch the mode to Mass or Volume and the field that has become the answer disappears from the form, so you are never asked for the number you came here to find. The working table shows both inputs converted to SI first — where unit mistakes surface — then the division, then the result back in the unit you picked.

When you have a shape rather than a measured volume, open the Volume from a shape panel and give it dimensions. A 10 cm cube is 1,000 cm³; a cylinder 10 cm across and 10 cm tall is 785.398 cm³; a sphere 10 cm across is 523.599 cm³. That volume feeds the calculation directly, so a turned bar or a printed sphere needs no separate geometry step on paper.

For an irregular solid, use displacement. Fill a graduated cylinder part way, record the level, lower the object in until it is fully submerged, record the new level, and take the difference. Weigh the object dry first, then divide. Two kinds of object defeat the method: anything that dissolves or soaks up water, and anything that floats, since a floater will not submerge itself and has to be pushed under with a rod or held down by a sinker of known volume.

In Volume mode the page adds a line most calculators skip — the edge of a cube holding the answer. A result of 12.94 cm³ means little on its own; "a cube 2.35 cm on a side" is something you can picture in your hand before you cut any stock.

The Density Formula and Its Two Rearrangements

\rho = \dfrac{m}{V}

$\rho$ = Density — mass per unit volume, in kg/m³ (SI) or g/cm³. The Greek letter is read "rho"
$m$ = Mass of the sample, in kilograms in SI. Mass, not weight: a force in newtons or pounds-force is a different quantity
$V$ = Volume the sample occupies, in cubic meters in SI. Measured, calculated from dimensions, or found by displacement

The formula for density is density = mass ÷ volume. Because it is a single division with no constant bolted onto it, the same relation rearranges into the other two questions people bring to it:

\rho = \frac{m}{V} \qquad m = \rho V \qquad V = \frac{m}{\rho}

Mass from density and volume is a multiplication: aluminum at 2.699 g/cm³ occupying 100 cm³ weighs 269.9 g. Volume from mass and density mirrors the first form: 250 g of gold at 19,320 kg/m³ takes up 12.94 cm³. Those are the three modes of this calculator, and the substitution line under the answer is printed in whichever direction you asked for, so the algebra you would have done on paper is already on screen.

The SI unit follows from the definition rather than from convention. A kilogram divided by a cubic meter is a kilogram per cubic meter, and every other density unit is a multiple of that one. It is also why 1 g/cm³ equals exactly 1,000 kg/m³: a gram is a thousandth of a kilogram and a cubic centimeter is a millionth of a cubic meter, so the ratio comes out a clean factor of a thousand. Nothing in the relation is measured or approximate — the only precision question is the precision of your own mass and volume.

Significant figures are the honest part of the answer. A balance reading 250 g to three figures and a cylinder reading 100 cm³ to three figures cannot produce a density good to eight, so the calculator carries about six on Auto and lets you pin it anywhere from three to eight. Pin it to the weaker of your two measurements and the result stops claiming precision that was never there.

Relative density is the same figure divided by a reference density. Water at its maximum, 999.975 kg/m³ near 4 °C, is the reference for solids and liquids, and dry air at 1.205 kg/m³ takes over when the material picked is a gas. Dividing a density by a density cancels the units away, which is why a datasheet can print 7.85 and mean the same steel whether the reader works in kg/m³ or lb/ft³.

Worked Density Examples

The classroom case: 250 g in 100 cm³

Mass 250 g, volume 100 cm³, and the division gives 2.5 g/cm³ — the value this page opens on. In SI that is 2,500 kg/m³, a relative density of 2.50006 against water, and a verdict of sinks. The closest entry in the material table is graphite, whose published span of 2,300 to 2,700 kg/m³ has its midpoint exactly there; common glass at 2,400 to 2,800 and concrete at 2,300 sit alongside it. A sample landing here is far more likely to be a mineral, a glass or a ceramic than a metal: magnesium, the lightest structural metal in the table, is already 1,740 kg/m³ and aluminum is 2,699.

Mass from density and volume: an aluminum block

Switch the mode to Mass, pick Aluminum from the metals group — it fills 2.699 g/cm³, the NIST elements value — and enter 100 cm³. The answer is 269.9 g. This is the maker's version of the question: instead of measuring a part to find out what it is, you know the material and want the finished weight before you cut anything. Milling a 100 cm³ pocket out of that block removes 269.9 g, while the same 100 cm³ in carbon steel at 7,850 kg/m³ would weigh 785 g. That three-to-one ratio is why aluminum wins any part that has to be lifted, flown or pedaled.

Volume from mass and density: 250 g of gold

In Volume mode, 250 g of gold at 19,320 kg/m³ occupies 12.94 cm³, and the cube-edge line puts that at 2.35 cm on a side — about a large sugar cube. Gold's density is why a small bar lifts so heavy, and why density has always been the first authenticity check: a fake at 15,000 kg/m³ would need 16.67 cm³ for the same 250 g, a gap obvious in a graduated cylinder long before it is obvious in the hand. Only one metal is close enough to survive that test. Tungsten sits at 19,300 kg/m³ against gold's 19,320, within a tenth of a percent, which is exactly why it turns up in counterfeit bars.

Does it float? An oak beam at 2 kg and 2.5 L

A beam weighing 2 kg that displaces 2.5 L is 0.8 kg/L, or 800 kg/m³. Relative density 0.80002, verdict floats, and the subtitle reports 80% of it below the surface — for a floating object the submerged fraction is simply its relative density. The nearest table entry is beech at 800 kg/m³, while the table's oak sits at 750 with a published range of 600 to 900, so a beam measuring 800 is a dense but unremarkable oak. Wood is the group where ranges matter most: fifteen of the sixteen woods here are published as spans, because a species is a description and not a specification.

Trade units: what a cubic foot of steel weighs

Set the mode to Mass, pick Carbon steel at 7,850 kg/m³, enter a volume of 1 ft³ and choose pounds for the mass unit. The answer is 490.059 lb — 222.287 kg — which is where the shop-floor rule that steel runs 490 pounds a cubic foot comes from. The same setup sizes stock: a 8 ft × 4 ft steel plate a quarter-inch thick is 0.667 ft³, so it lands at 326.706 lb — 148.191 kg — which is the number that decides whether two people can carry it or you book a lift. Mixed units are the risk in this kind of job, which is why the working table shows the SI step first — 1 ft³ becomes 0.0283168 m³, and the multiplication happens there where you can check it.

The air in a room weighs more than you expect

A 3 m × 4 m room with a 2.5 m ceiling holds 30 m³ of air. At 1.205 kg/m³ — dry air at 20 °C and 101.325 kPa — that air weighs 36.15 kg, just under 80 pounds of a substance most people treat as weightless. It is the example that makes the formula stick, and it also shows why a gas density is meaningless without its conditions: the same air at 0 °C is about 7% denser, so the same room would hold about 2.6 kg more of it. Gases are the one group in this table where the stated condition moves the answer enough to argue about.

Density of Common Materials

Material	kg/m³	g/cm³	Notes
Hydrogen	0.0838	0.0000838	Gas at 20 °C, 101.325 kPa — lightest entry in the table
Dry air	1.205	0.001205	At 20 °C, 101.325 kPa; the reference for gas relative density
Balsa	125	0.125	Published range 110–140; midpoint shown
Oak	750	0.750	Published range 600–900; midpoint shown
Ice	917	0.917	Floats, 91.7% submerged in fresh water
Polyethylene	930	0.930	NIST compounds table
Water	998.21	0.99821	At 20 °C; peaks at 999.975 kg/m³ near 4 °C
Seawater	1,025	1.025	At 25 °C; the reason a few materials float at sea and sink in a lake
Concrete	2,300	2.300	NIST compounds table
Aluminum	2,699	2.699	NIST elements table
Granite	2,700	2.700	Published range 2,600–2,800; midpoint shown
Carbon steel	7,850	7.850	Engineering reference
Mercury	13,550	13.550	The densest liquid here — lead floats on it
Gold	19,320	19.320	NIST elements table
Osmium	22,570	22.570	NIST elements table — densest entry

Where Density Calculations Go Wrong

Pairing a mass unit with a volume unit that does not match it. Grams over cubic centimeters gives g/cm³; kilograms over cubic meters gives kg/m³; grams over cubic meters gives a number a million times too small. It is why the working table converts both inputs to SI before dividing — the mismatch surfaces there instead of hiding in the answer.
Treating weight in pounds-force as mass. Density is mass per volume, never force per volume. Force per volume is specific weight, and water carries both figures at once: about 1,000 kg/m³ as a density, 62.4 lbf/ft³ as a specific weight. Feed a pounds-force figure into a mass field in US engineering units and the result comes out roughly 32 times too large.
Measuring bulk density and calling it density. Sand, soil, sawdust, gravel and every powder measured by the space it fills include the air between the grains. Dry sand fills a container at 1,400 to 1,600 kg/m³ while the quartz grains themselves are 2,650 kg/m³ — a gap of more than 40%. Loose material in a container gives you bulk density, which is a real and useful quantity, but not the density of the material.
Using a gas value without its temperature and pressure. Every gas figure in this calculator is quoted at 20 °C and 101.325 kPa. The same gas at 0 °C is about 7% denser, and published tables routinely print one or the other without saying which. For solids the temperature effect is far smaller — under a tenth of a percent across normal room temperatures — so this is a gas problem first and everything else second.
Reading a range midpoint as a specification. Forty-two of the 121 materials here are published as spans: oak from 600 to 900 kg/m³, granite from 2,600 to 2,800. The picker fills the midpoint and a line under the answer names the span it came from. For a load calculation or a shipping weight, narrow it with your own sample rather than defending a midpoint to three decimal places.
Swapping density for relative density. Relative density has no units, because it is a density divided by water's: steel is 7,850 kg/m³ and 7.850 relative. Type 7,850 into a field expecting the dimensionless figure, or 7.85 into one expecting kg/m³, and every downstream number moves by three orders of magnitude. This page prints both side by side so the pair is hard to confuse.
Trying to measure a floater by displacement. Water displacement needs the object fully under. Most woods, foams and cork sit below 1,000 kg/m³ and bob, so the level you read reflects only the part that sank. Push the sample under with a thin rod, or attach a sinker of known volume and subtract it afterwards.

Density Terms Explained

Density (ρ)

Mass per unit volume, ρ = m ÷ V. SI unit kilogram per cubic meter (kg/m³); the common laboratory unit g/cm³ is 1,000 times larger. It is a property of the material and not of the piece: a nail and a girder cut from the same steel share one density.

Relative density (specific gravity)

A density divided by a reference density, which leaves it with no units. Water at its maximum, 999.975 kg/m³ near 4 °C, is the reference for solids and liquids; dry air at 1.205 kg/m³ is used for gases. Steel at 7,850 kg/m³ has a relative density of 7.850.

Bulk density

The mass of a loose material divided by the total space it fills, voids counted in. It applies to soils, aggregates, powders and grain, always falls below the density of the particles themselves, and rises when the material is compacted or vibrated.

Buoyancy

The upward force on a submerged object, equal to the weight of the fluid it pushes aside — Archimedes' principle. It decides the float card: below water's density the verdict is Floats, above it Sinks, and within half a percent of it Neutrally buoyant. For a floater the fraction below the surface is its density divided by water's — read against water even when the relative-density card is quoting a gas against air. Ice at 917 kg/m³ floats 91.7% submerged in fresh water.

Displacement method

Finding the volume of an irregular solid by submerging it and reading the rise in liquid level, since the liquid pushed aside occupies exactly the volume of the object. Unsuitable for anything that dissolves, absorbs water, or floats without being held under.

Specific weight

Weight per unit volume — a force divided by a volume, in N/m³ or lbf/ft³. Numerically it is density multiplied by gravitational acceleration. US engineering tables list water as both 1,000 kg/m³ and 62.4 lbf/ft³, which is where the confusion with density usually starts.

Significant figures

The digits in a result that the measurements behind it actually support. A mass and a volume each known to three figures cannot produce a density known to six. This calculator carries about six on Auto and can be pinned anywhere between three and eight.

Density Calculator — Frequently Asked Questions

How do I calculate density?

Divide mass by volume: ρ = m ÷ V. A 250 g sample filling 100 cm³ has a density of 2.5 g/cm³, which is 2,500 kg/m³. Keep the units paired — grams with cubic centimeters, kilograms with cubic meters.

What is the formula for density?

The formula for density is density = mass ÷ volume, written ρ = m ÷ V. It rearranges to m = ρ × V for mass and V = m ÷ ρ for volume, which are the other two modes of this calculator.

How do I find volume from mass and density?

Divide the mass by the density. In SI, 250 g of gold — 0.25 kg — divided by 19,320 kg/m³ gives 0.00001294 m³, which is 12.94 cm³. Set the mode to Volume and the calculator does that division and adds the edge of a cube holding the answer, 2.35 cm here, so the volume becomes something you can picture.

How do I find mass from density and volume?

Multiply density by volume. Aluminum at 2.699 g/cm³ occupying 100 cm³ weighs 269.9 g, and a cubic foot of carbon steel at 7,850 kg/m³ weighs 490.059 lb. Set the mode to Mass, pick the material or type its density, and enter the volume in whatever unit you measured it in.

Will my object float or sink in water?

Anything below about 1,000 kg/m³ floats in fresh water and anything above it sinks. The float card states which, and for a floater it gives the fraction below the surface: ice at 917 kg/m³ floats with 91.7% submerged. Seawater is denser at about 1,025 kg/m³, which is why the classic iceberg figure is nearer 89.5% and why a few materials that just sink in a lake will float at sea. Body fat at 950 kg/m³ floats while muscle at 1,050 sinks, which is the physics behind lean swimmers riding low in the water. Hollow and foamed objects are settled by their average density with the trapped air counted, not by the density of the material they are made from.

What is the difference between density and specific gravity?

Density is absolute and carries units — kg/m³ in SI. Specific gravity, also called relative density, is that density divided by water's, so it has no units at all. The UK's National Physical Laboratory gives the reference as water at 4 °C, where it is at its densest. This calculator shows density on the main card and relative density beside it, measured against water for solids and liquids and against dry air for gases.

How do I convert specific gravity to density?

Multiply the specific gravity by the density of water, 999.975 kg/m³ at its maximum — near enough 1,000 for most work. A crude oil at 0.87 specific gravity is about 870 kg/m³, and a mineral at 2.65 is about 2,650 kg/m³.

How do I find the density of a liquid?

Weigh a dry, empty container, fill it to a marked volume, and weigh it again. The difference in mass divided by that volume is the density. A graduated cylinder holding 100 mL and gaining 78.9 g of ethanol gives 0.789 g/cm³, which is the table value for ethanol at 20 °C. Enter the mass difference and the volume here and the working table handles the unit step.

How do I measure the density of an irregularly shaped object?

Weigh it, then find its volume by displacement: note the level in a graduated cylinder, submerge the object, note the new level, and take the difference. Divide mass by that volume. The method fails on anything that dissolves or absorbs water, and a floating object has to be held under before the reading means anything.

How do I calculate the density of a mixture?

Add the masses, add the volumes, and divide the totals — never average the two densities, because that is only correct when the two volumes happen to be equal. There is a further catch with solutions: mixing ethanol and water produces slightly less volume than the two parts started with, so a mixture worth reporting is one you measure rather than predict.

What is the density of water?

Fresh water reaches its maximum density of 999.975 kg/m³ near 4 °C, which is where the textbook 1,000 kg/m³ comes from. At 20 °C it is 998.21 kg/m³, the value carried in this calculator's material table. Water is unusual in getting less dense as it cools past 4 °C toward freezing, and that is why lakes ice over from the surface down instead of from the bottom up.

Why does the calculator show a range for wood, rock and concrete?

Because those materials are published as ranges rather than single values. Oak runs 600 to 900 kg/m³ and granite 2,600 to 2,800, depending on grain, moisture and mineral content. Forty-two of the 121 materials here carry a span; the picker fills the midpoint and a line under the answer names the span, so you can replace it with a figure measured from your own sample.

What is the densest material in the table?

Osmium at 22,570 kg/m³, with iridium a close second at 22,420. Those two are the densest elements known, and they sit close enough that the gap depends on whose measurement you read — other published figures put the pair at 22,590 and 22,560 kg/m³. Mercury at 13,550 kg/m³ is the densest liquid in the table, dense enough that lead at 11,350 floats on it. At the light end, hydrogen at 0.0838 kg/m³ is roughly 270,000 times lighter than the osmium.

Can I use this to work out freight density in pounds per cubic foot?

Yes. Enter the total shipment weight in pounds and the total volume in cubic feet and the answer reads in pounds per cubic foot, the figure carriers call PCF — the same calculation they publish: weight including packaging, divided by length × width × height in inches ÷ 1,728. What this page will not do is assign an NMFC freight class. Old Dominion's own density tool calls a class suggested from density alone an estimate to be verified against the NMFC, and the reason is that classification also weighs stowability, handling and liability alongside density.

Does temperature change the density I get here?

It changes the material, not the arithmetic. This calculator takes no temperature input: it divides the mass and volume you supply, so a measurement made at any temperature gives the correct density for that temperature. The stored material values carry their own conditions instead — gases at 20 °C and 101.325 kPa, water at 20 °C. Solids shift under a tenth of a percent across normal room temperatures, liquids rather more — water moves about 0.1% over five degrees and ethanol nearly ten times that, while a gas moves about 7% between 0 °C and 20 °C.

Where do the material densities come from, and how accurate are they?

Fifty-two of the 121 values are traceable to NIST — 26 from its X-ray attenuation table of elements, 16 from the compounds table and 10 from the Chemistry WebBook — and the remaining 69 come from engineering reference tables. Each row names its own source and condition, and range materials show the published span instead of a false single value. The division itself is exact, so the uncertainty in your answer is the uncertainty in your own mass and volume readings.

Is this density calculator free?

Yes. Nothing is stored and nothing is sent anywhere — the whole calculation runs in the page you are reading. All three modes, the 121-material table, the shape helper and the step-by-step working sit on the one page, and the address bar keeps your inputs so a link reopens the same calculation.

Can this calculator convert a density between units?

Each field has its own unit menu, so a mass in pounds and a volume in liters need no preparation, and the answer is repeated in the other density units as a courtesy strip. Restating a figure you already have is a different job, and the density converter is the page built for it.

Sources & References

Content verified by the Smart Calculators Team