Calculate density, mass, or volume using the density equation (ρ = m / V). Pick what you want to solve for, enter two known values, and get instant results with full unit conversions. Select a material from the built-in database of 100+ substances to auto-fill density, or use the mystery material identifier to figure out what an unknown sample might be.
Pro tip: Density determines whether something floats or sinks. Anything with density less than 1.0 g/cm³ floats in water. This is why ice floats (0.917 g/cm³), wood floats (0.4–0.8 g/cm³), but most metals sink. Mercury is so dense (13.53 g/cm³) that iron balls float in it.
Enter object density and liquid density to determine if the object floats, sinks, or is neutrally buoyant.
| Material | Category | Density (g/cm³) |
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How to Calculate Density (Formula and Examples)
Density is defined as mass per unit volume, expressed by the formula ρ = m / V, where ρ (rho) is density, m is mass, and V is volume. Rearranging the equation lets you solve for any unknown: m = ρ × V to find mass, or V = m / ρ to find volume. For example, a block of aluminum with a mass of 270 grams and a volume of 100 cm³ has a density of 2.70 g/cm³. Conversely, if you know you have copper (8.96 g/cm³) and 500 cm³ of it, the mass is 8.96 × 500 = 4,480 grams. Density is always expressed as a mass unit divided by a volume unit: grams per cubic centimeter, kilograms per cubic meter, or pounds per cubic foot are the most common choices.
Density of Common Materials (Reference Table)
Materials span an enormous range of densities. Gases at standard temperature and pressure are extremely light — air is only about 0.0012 g/cm³ and hydrogen is less than 0.00009 g/cm³. Most woods range from 0.16 g/cm³ (balsa) to around 1.1 g/cm³ (ebony), with common species like oak (0.71) and pine (0.51) in between. Plastics cluster between 0.9 and 2.2 g/cm³, while common liquids range from about 0.75 (gasoline) to 13.53 (mercury). Metals show the widest spread: aluminum sits at 2.70 g/cm³, steel at 7.85, gold at 19.32, and platinum at 21.45. Knowing these reference values lets you quickly estimate whether a measurement makes sense and helps identify unknown samples.
Why Density Matters in Engineering and Manufacturing
In engineering, density is a critical factor in material selection. Aerospace engineers favor aluminum and titanium because their high strength-to-density ratios reduce aircraft weight, improving fuel efficiency. Civil engineers must know the density of concrete, steel, and soil to calculate loads on foundations and bridges. In manufacturing, density determines how much raw material you need to produce a given number of parts — a casting designer must account for the density of molten metal to size molds correctly. Quality control teams use density measurements to detect porosity, voids, or contamination in finished products. Even packaging engineers rely on density to estimate shipping weights and optimize container utilization.
Buoyancy: Using Density to Predict Floating and Sinking
Archimedes’ principle states that an object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces. The practical consequence is straightforward: if an object’s density is less than the fluid’s density, it floats; if greater, it sinks. This is why ships made of steel (7.85 g/cm³) can float — the hull encloses a large volume of air, making the average density of the entire vessel less than that of water (1.0 g/cm³). Submarines control buoyancy by flooding or emptying ballast tanks, changing their effective density relative to seawater (1.025 g/cm³). In petroleum geology, the density contrast between oil, water, and rock determines where hydrocarbons accumulate in underground reservoirs. Understanding buoyancy is also essential for designing life jackets, pontoon bridges, and hot-air balloons.
Density Calculator FAQ
What units should I use for density? The most common unit in science is
g/cm³ (grams per cubic centimeter), which is numerically identical to g/mL. Engineers
often use kg/m³ (multiply g/cm³ by 1,000) or lb/ft³ (multiply g/cm³ by
62.428). This calculator converts between all three automatically.
Why does my measured density not exactly match the database? Published densities
are for pure materials at standard conditions (typically 20–25 °C and 1 atmosphere).
Temperature, pressure, alloy composition, moisture content, and porosity all affect real-world
measurements. A small discrepancy is normal; large deviations suggest the sample may be a
different material or contain voids.
Can I use this to identify an unknown material? Yes. Measure the mass and volume
of your sample, let the calculator find the density, and check the mystery material identifier.
It will suggest the closest match from the database. For reliable identification, combine density
with other tests such as hardness, magnetism, or conductivity.
How do I measure volume of an irregular object? Use water displacement: fill a
graduated cylinder partway, note the level, submerge the object, and note the new level. The
difference in milliliters equals the volume in cubic centimeters.
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