Density Calculator

About Density Calculator

The Density Formula and How to Use It

Density equals mass divided by volume: d = m/V. Rearranging gives m = d x V (to find mass) and V = m/d (to find volume). The SI unit is kilograms per cubic metre (kg/m³), though grams per cubic centimetre (g/cm³) is more common in chemistry because water has a convenient density of 1.00 g/cm³ at 4 °C.

Solve For	Formula	Example
Density	d = m / V	500 g / 200 cm³ = 2.5 g/cm³
Mass	m = d x V	7.87 g/cm³ x 100 cm³ = 787 g
Volume	V = m / d	1,000 g / 19.3 g/cm³ = 51.8 cm³

Worked example: a block of aluminium has a mass of 2,700 g and a volume of 1,000 cm³. Density = 2,700 / 1,000 = 2.70 g/cm³, matching the known density of aluminium. If you only knew the density and mass, you could rearrange to V = 2,700 / 2.70 = 1,000 cm³.

Density Unit Conversions

Different fields use different density units. The calculator converts between all of them automatically, but it helps to know the relationships.

Unit	Equivalent	Common In
1 g/cm³	1,000 kg/m³	Chemistry, materials science
1 g/mL	1 g/cm³ (identical)	Liquid measurements
1 kg/m³	0.001 g/cm³	SI standard, engineering
1 lb/ft³	16.018 kg/m³	US construction, shipping
1 kg/L	1,000 kg/m³	Beverage and food industry

Quick conversion: to go from g/cm³ to kg/m³, multiply by 1,000. To go from lb/ft³ to kg/m³, multiply by 16.018.

Reference Densities of Common Materials

Knowing typical densities helps identify unknown materials, check if something will float, and estimate weights for shipping or construction.

Material	Density (kg/m³)	Density (g/cm³)	Floats in Water?
Air (sea level, 20 °C)	1.2	0.0012	Yes (gas)
Cork	120 - 240	0.12 - 0.24	Yes
Oak wood	600 - 900	0.60 - 0.90	Usually yes
Ice	917	0.917	Yes
Water (4 °C)	1,000	1.000	-
Seawater	1,025	1.025	-
Concrete	2,300	2.30	No
Aluminium	2,700	2.70	No
Iron / Steel	7,874	7.87	No
Copper	8,960	8.96	No
Lead	11,340	11.34	No
Gold	19,320	19.32	No
Osmium (densest element)	22,590	22.59	No

Why Does Density Matter?

Density connects mass and volume in nearly every branch of science and engineering. Here are the most common reasons people need to calculate it.

Application	Why Density Is Needed	Example
Buoyancy and flotation	An object floats if its density is less than the surrounding fluid (Archimedes' principle)	Ships use hull shapes that lower average density below 1,025 kg/m³ (seawater)
Material identification	Measuring density can confirm what a material is	A jeweller checks whether a ring is real gold (19.3 g/cm³) or plated brass (8.5 g/cm³)
Shipping and logistics	Carriers charge by dimensional weight, which uses volume and assumed density	Dimensional weight formula: L x W x H / 5,000 (cm to kg)
Concrete and construction	Estimating weight of poured materials	A 10 cm slab over 50 m² needs 5 m³ of concrete at 2,300 kg/m³ = 11,500 kg
Chemistry and solutions	Converting between mass and volume of liquids	Ethanol density 0.789 g/mL means 1 litre weighs 789 g, not 1,000 g
Food and cooking	Ingredient weight varies by density	1 cup of flour (about 125 g) vs 1 cup of sugar (about 200 g) - same volume, different mass

Measuring Density in Practice

For regular shapes (cubes, cylinders, spheres), measure dimensions with a ruler or callipers, calculate volume using the geometry formula, then weigh the object. For irregular shapes, use water displacement: submerge the object in a graduated cylinder and note the volume change. Divide mass by the displaced volume to get density.

Method	Best For	Accuracy
Ruler + scale	Regular-shaped solids	Good (depends on measurement precision)
Water displacement	Irregular solids that do not dissolve	Good for lab work
Hydrometer	Liquids (beer, wine, battery acid)	High for liquids
Pycnometer	Fine powders and granules	Very high

Temperature and Density

Most materials expand when heated, so density decreases as temperature rises. Water is a notable exception - it reaches maximum density at about 4 °C, which is why ice floats and lakes freeze from the top down. Gases are especially sensitive to temperature: air density drops from 1.29 kg/m³ at 0 °C to 1.16 kg/m³ at 30 °C, a 10% change. Hot air balloons exploit this difference to generate lift.

The thermal expansion coefficient quantifies this effect. Water expands by about 0.021% per °C near room temperature, steel by about 0.0036% per °C, and air by roughly 0.34% per °C at constant pressure (per the Ideal Gas Law). For precision work - calibrating glassware, pouring concrete, or refuelling aircraft - engineers reference temperature-density tables from NIST or the CRC Handbook rather than using a single figure.

Specific Gravity and Relative Density

Specific gravity (SG) is density divided by the density of water at 4 °C, so it is a dimensionless number. Gold has a specific gravity of 19.32, meaning it is 19.32 times heavier than an equal volume of water. Brewers, winemakers, and battery technicians all use specific gravity because the numbers are easier to read on a hydrometer than raw density values.

Fluid	Typical SG	What It Tells You
Fresh wort (beer)	1.040 - 1.060	Sugar content before fermentation
Finished beer	1.005 - 1.015	Residual sugars after yeast work
Grape must (wine)	1.080 - 1.100	Predicts final alcohol percentage
Car battery acid (charged)	1.265 - 1.299	State of charge of lead-acid cell
Urine (medical)	1.002 - 1.030	Hydration and kidney function
Blood plasma	1.025	Reference for medical centrifuge separation

The API gravity scale used in the petroleum industry is derived from specific gravity with the formula API = (141.5 / SG) - 131.5. Light crude oils have API values above 31.1, heavy crudes below 22.3 - the difference drives pricing, refinery routing, and export classification.

Common Mistakes When Calculating Density

Most density errors trace back to three patterns: mixing unit systems, ignoring cavities, and confusing bulk density with particle density.

• Mixing units: plugging mass in grams and volume in m³ without converting returns a number one million times too small. Always convert to a single system before dividing.
• Cavities and voids: a drilled or hollow object has a lower apparent density than the solid material. A steel pipe has the same material density (7,874 kg/m³) as a steel bar but a much lower bulk density.
• Bulk vs particle density: a bag of sand weighs less per litre than a solid block of the same mineral because the gaps between grains count in bulk volume. Bulk density of dry sand is around 1,600 kg/m³, while quartz particles themselves are 2,650 kg/m³.
• Trapped air in displacement: when measuring volume by submerging an object, surface bubbles can add millilitres of apparent volume. Tap the cylinder and coat porous objects with a thin oil film to get accurate readings.
• Scale drift: a balance reading 0.2 g low on a 10 g sample skews density by 2% - enough to mis-identify a metal. Zero and calibrate before weighing small samples.

How Was the Density of the Earth Measured?

The mean density of Earth is 5,515 kg/m³ - the highest of any planet in the solar system. This was first measured by Henry Cavendish in 1798 using a torsion balance to weigh the gravitational pull between lead spheres, an experiment now known as "weighing the Earth". Modern values come from satellite geodesy and seismology, with the NASA Planetary Fact Sheet listing 5.513 g/cm³. Earth is dense because of its iron-nickel core (around 11,000 kg/m³), which is why the planet has a strong magnetic field. The Sun, for comparison, averages 1,408 kg/m³ - less dense than Earth because it is mostly hydrogen and helium. Saturn, at 687 kg/m³, would float in water if you could find an ocean big enough.

For fluid mechanics problems involving pressure, the pressure calculator handles P = F/A and hydrostatic pressure. For estimating material weights in construction projects, the concrete calculator and cubic yards calculator factor in standard material densities automatically. All calculations run in your browser with no data sent to any server.

Sources

• NIST - SI Base Units and Derived Units
• NASA Goddard - Earth Fact Sheet (mean density)
• Encyclopaedia Britannica - Density
• The Engineering ToolBox - Densities of Common Materials
• USGS - Water Density by Temperature
• PubChem (NIH) - Osmium Element Data