Density Calculator

A density calculator finds density, mass, or volume from any two of them using ρ = mass ÷ volume. Enter mass and volume and it divides one by the other: a 250 g object filling 100 cm³ has a density of 250 ÷ 100 = 2.5 g/cm³ (2,500 kg/m³, or about 156 lb/ft³). Switch tabs to solve for mass or volume instead.

Density is a ratio, so it sits alongside our other math ratios. Use this tool for mass-per-volume; for a share of a whole use the Percentage Calculator, for growth between two numbers the Percentage Increase Calculator or the signed Percentage Change Calculator, and for a marked-down price the Discount Calculator.

The density formula

Density (the Greek letter rho, ρ) is defined as mass divided by volume:

Rearranged, the same equation gives you mass or volume when density is known:

Here m is mass, V is volume, and ρ is density. Density is an intensive property - it does not change with the amount of material. A teaspoon of pure gold and a gold bar have identical density (19.3 g/cm³); only their mass and volume differ.

A worked example

Suppose you have an object with a mass of 250 grams and a volume of 100 cubic centimeters. Plug those into the formula:

So the density is 2.5 g/cm³. Because 1 g/cm³ equals 1,000 kg/m³, that is also 2,500 kg/m³, and multiplying by 62.428 gives about 156.1 lb/ft³. A density of 2.5 g/cm³ is in the range of glass and many rocks. The calculator above shows all three units at once so you do not have to convert by hand.

How much does a 100 cm³ block weigh?

Rearranged to mass = density × volume, the same formula tells you the weight of a fixed-size block of each material. This table fixes the volume at 100 cm³ (about the size of a small ice cube tray cell) and multiplies by each density.

The same 100 cm³ of gold outweighs the pine by more than 45 to 1 - a vivid illustration of what density measures. To run this for any material and size, switch to the Mass tab and enter its density and your volume.

How to use this density calculator

1. Pick what to solve for. Use the Density, Mass, or Volume tabs at the top of the calculator. The input fields change to ask only for the values you need.
2. Enter the known values. Type the numbers and pick a unit from each dropdown - for example, 250 g and 100 cm³.
3. Choose the answer unit. The "Answer in" dropdown sets the unit for the value you are solving for; for density you can choose g/cm³, kg/m³, or lb/ft³.
4. Read the result. The large number is your answer, and the rows beneath it show the same result expressed in other common units.

The math runs instantly in your browser. Nothing is uploaded, and you can change inputs and recalculate as many times as you want.

Who this calculator is for

• Students in physics, chemistry, and earth science checking density, specific gravity, or unit-conversion problems.
• Makers and hobbyists estimating the weight of a 3D print, casting, or block of material before they buy or ship it.
• Engineers and trades converting between metric g/cm³ or kg/m³ and US lb/ft³ for material specs and load calculations.
• Cooks and brewers relating volume to weight for ingredients, where density (specific gravity) bridges the two.
• Anyone identifying a material by comparing a measured density against published values for metals, plastics, and liquids.

Measuring mass and volume

The calculator is only as accurate as your two measurements. Mass is easy: weigh the sample on a scale and use grams or pounds. Volume is where most errors creep in. For a regular shape you can compute volume from dimensions - a cube's volume is side cubed, a cylinder's is π r² h. For an irregular object, use water displacement: fill a graduated container, record the level, submerge the object fully, and read the new level. The rise in volume is the object's volume, because each milliliter of water displaced equals one cubic centimeter. This is the trick attributed to Archimedes and it works for any shape that does not absorb water.

Density units and converting between them

Three units cover almost every real situation, and they are all in this tool:

• g/cm³ (grams per cubic centimeter) - common in chemistry and labs. Numerically equal to g/mL, because 1 cm³ = 1 mL.
• kg/m³ (kilograms per cubic meter) - the SI unit, used in physics and most of the scientific world. 1 g/cm³ = 1,000 kg/m³.
• lb/ft³ (pounds per cubic foot) - common in US construction and engineering. 1 g/cm³ ≈ 62.428 lb/ft³.

To convert g/cm³ to kg/m³, multiply by 1,000; to go back, divide by 1,000. To convert g/cm³ to lb/ft³, multiply by about 62.43. When you solve for density, the calculator prints all three so you can copy whichever your problem needs.

Typical densities for reference

Comparing your result to known values is a quick sanity check and a way to identify an unknown material. Approximate densities at room temperature:

• Air: ~0.0012 g/cm³ (1.2 kg/m³)
• Cork: ~0.24 g/cm³ - floats easily
• Water: ~1.00 g/cm³ (1,000 kg/m³) - the reference point
• Concrete: ~2.4 g/cm³
• Aluminum: ~2.70 g/cm³
• Steel: ~7.85 g/cm³
• Lead: ~11.34 g/cm³
• Gold: ~19.30 g/cm³

Anything denser than water (above 1 g/cm³) sinks; anything less dense floats. That single rule explains why ice floats, why oil sits on water, and why a steel ship - mostly hollow air space - stays afloat even though steel itself sinks.

Density of common materials in g/cm³, kg/m³, and lb/ft³

This reference table converts each material's approximate room-temperature density into all three units and flags whether it floats in water. Values are approximate and shift with temperature, alloy, and purity.

Specific gravity

Specific gravity is just density measured against water. Because water is about 1 g/cm³, a material's specific gravity is numerically nearly the same as its density in g/cm³ but carries no units. A mineral with a density of 3.5 g/cm³ has a specific gravity of about 3.5, meaning it is 3.5 times as heavy as an equal volume of water. Geologists and gemologists lean on specific gravity to tell similar-looking minerals apart, since it is a fixed, easily measured property.

What changes a material's density

• Temperature: heating most substances expands their volume and lowers density. This is why hot air rises and why density is quoted at a stated temperature.
• Pressure: gases compress dramatically under pressure, raising density; liquids and solids change much less.
• Phase: the same substance has very different densities as a solid, liquid, or gas - steam is far less dense than liquid water.
• Composition and purity: alloys, impurities, and air pockets (porosity) shift the measured density away from the pure-material value.
• Dissolved substances: salt water is denser than fresh water, which is why you float more easily in the ocean.

Tips for accurate results

• Keep units consistent in your head even though the calculator handles conversion - it helps you spot a wrong dropdown choice.
• Remove trapped air when measuring volume by displacement; bubbles clinging to an object inflate the volume and lower the density.
• Use enough significant figures on your scale and graduated cylinder; a small mass or volume error has an outsized effect on the ratio.
• Note the temperature if precision matters, especially for liquids, and compare against reference values measured at the same temperature.

Limitations and assumptions

This is a planning and learning tool, not a metrology instrument. Keep these assumptions in mind:

• It assumes a uniform sample - one material with no voids or layers. Porous or composite objects give an "average" bulk density, not the true material density.
• It does not correct for temperature or pressure; the result is exact only for the conditions at which you measured.
• It ignores buoyancy of air on the scale, which is negligible for everyday work but matters in precise lab measurements.
• Conversions use fixed factors (1 g/cm³ = 1,000 kg/m³ = 62.428 lb/ft³), so any error comes from your input values, not the math.

Where density shows up in real life

Density is not just a textbook number - it quietly decides outcomes all around you. In shipping and logistics, carriers charge by a blend of weight and space, and a low-density package (light but bulky) can cost more than a small heavy one; that is exactly why freight class is built on density. In cooking and baking, a cup of flour and a cup of honey weigh very different amounts because their densities differ, which is why precise recipes give weights, not volumes. In medicine, urine and blood density (specific gravity) are routine diagnostic clues. In metallurgy and recycling, density separates aluminum from steel from lead on a sorting line. And in everyday safety, the fact that gasoline floats on water - it is less dense - is why a fuel fire cannot simply be put out with water.

Once you can measure mass and volume, this density calculator turns those two everyday numbers into the property that explains all of the above. The same rho = mass ÷ volume relationship that a student uses for a homework cube is what an engineer uses to spec a beam and what a jeweler uses to flag a fake gold coin: real 24-karat gold must come in at about 19.3 g/cm³, and a lighter reading gives the counterfeit away.

Related calculators

Density is a ratio, so these tools pair naturally with it. To work the underlying arithmetic, use the Ratio Calculator or the Percentage Calculator. For trig, logs, and powers you can reach for the Scientific Calculator, and to average several repeated density measurements use the Average Calculator or the Standard Deviation Calculator.

About this formula

Density = mass ÷ volume is a fundamental, exact definition in physics - it needs no external data source, only your two measurements. The conversion constants used here are the standard SI and US customary definitions: 1 kilogram = 1,000 grams, 1 meter = 100 centimeters (so 1 m³ = 1,000,000 cm³), 1 pound = 453.59237 grams, and 1 cubic foot = 28,316.846592 cm³. Combining them gives the published equivalences 1 g/cm³ = 1,000 kg/m³ = 62.428 lb/ft³.