A density calculator solves the relationship between three variables: density, mass, and volume. Give it any two and it returns the third. This tool covers all three directions from one screen, supports 21 unit combinations across mass, volume, and density, and includes a material reference table so you do not need to look up values elsewhere.
The Density Formula
Density is mass per unit volume. More mass in the same space means higher density. Less mass in the same space means lower density.
The formula: ρ = m ÷ V
ρ is density (rho), m is mass, V is volume.
Rearranged for each variable:
| You Want | Formula | In Words |
|---|---|---|
| Density (ρ) | ρ = m ÷ V | Divide mass by volume |
| Mass (m) | m = ρ × V | Multiply density by volume |
| Volume (V) | V = m ÷ ρ | Divide mass by density |
The calculator knows which variable you are solving for and greys out that field. You fill in two values, it fills in the third.
Find Density Mode
You have measured an object. You know how much it weighs and how much space it takes up. You want to know its density.
Select Find Density. Enter the mass and pick your unit: kg, g, mg, lb, oz, tonne (metric), or US ton. Enter the volume and pick your unit: m³, cm³, mm³, litres, mL, ft³, in³, or US gallons. Click Calculate.
The density field is greyed out because it is the answer.
Example: a block of material has a mass of 540 g and occupies 200 cm³.
ρ = 540 ÷ 200 = 2.70 g/cm³ — that matches aluminium in the reference table.
| Mass | Volume | Density | Material |
|---|---|---|---|
| 540 g | 200 cm³ | 2.70 g/cm³ | Aluminium |
| 1 kg | 1 L | 1.00 g/cm³ | Water |
| 19.32 kg | 1,000 cm³ | 19.32 g/cm³ | Gold |
| 7.87 g | 1 cm³ | 7.87 g/cm³ | Iron |
| 789 g | 1 L | 0.789 g/cm³ | Ethanol |
The result panel converts your density answer to g/cm³, kg/m³, and lb/ft³ automatically. No separate conversion needed.
Find Mass Mode
You know what the material is and how big the object is. You need the total mass before it arrives, before you lift it, or before you load it.
Select Find Mass. Enter the density and unit (kg/m³, g/cm³, g/mL, kg/L, lb/ft³, or lb/in³). Enter the volume. Click Calculate.
Example: a concrete slab measuring 2m × 1m × 0.15m. Volume = 0.3 m³. Concrete density = 2,300 kg/m³.
m = 2,300 × 0.3 = 690 kg
| Material | Density | Volume | Mass |
|---|---|---|---|
| Concrete | 2,300 kg/m³ | 0.3 m³ | 690 kg |
| Aluminium | 2,700 kg/m³ | 0.5 m³ | 1,350 kg |
| Water | 1,000 kg/m³ | 2 L | 2 kg |
| Gold | 19,320 kg/m³ | 10 cm³ | 193.2 g |
| Pine Wood | 510 kg/m³ | 1 m³ | 510 kg |
The gold row is worth pausing on. 10 cm³ is roughly the size of a large sugar cube. At gold’s density, that cube weighs just over 193 grams — about the same as a full can of soft drink.
Find Volume Mode
You have a known mass of material and need to know how much space it takes up. This comes up in packaging, storage planning, container sizing, and lab work.
Select Find Volume. Enter the mass and the density. Click Calculate.
Example: 500 grams of olive oil at a density of 0.91 g/cm³.
V = 500 ÷ 0.91 = 549.45 cm³
| Material | Mass | Density | Volume |
|---|---|---|---|
| Olive Oil | 500 g | 0.91 g/cm³ | 549.45 cm³ |
| Iron | 7,870 g | 7.87 g/cm³ | 1,000 cm³ |
| Air | 1.2 g | 0.0012 g/cm³ | 1,000 L |
| Mercury | 135.3 g | 13.53 g/cm³ | 10 cm³ |
| Ice | 917 g | 0.917 g/cm³ | 1,000 cm³ |
The air row shows why gases take up so much space: 1.2 grams fills a full litre. The mercury row shows the opposite: 135 grams fits into 10 cm³, a space about the size of a walnut.
Floats or Sinks Indicator
Every result includes a buoyancy check. The threshold is 1.00 g/cm³, the density of water at 4°C.
Below 1.00 g/cm³: the material floats. Above: it sinks.
| Material | Density | Result |
|---|---|---|
| Pine Wood | 0.51 g/cm³ | Floats |
| Ice | 0.917 g/cm³ | Floats |
| Water | 1.00 g/cm³ | Neutrally buoyant |
| Concrete | 2.30 g/cm³ | Sinks |
| Steel | 7.85 g/cm³ | Sinks |
| Gold | 19.32 g/cm³ | Sinks |
Ice floating on water is a direct result of hydrogen bonding. When water freezes, its molecules form a hexagonal lattice structure that takes up more space than liquid water. That gives ice a density of 0.917 g/cm³, lower than liquid water at 1.00 g/cm³. Lakes freeze from the top down rather than the bottom up because of this. The difference is only 0.083 g/cm³, but it keeps aquatic ecosystems alive through winter.
Note: the buoyancy check compares against fresh water at 4°C. In seawater (approximately 1.025 g/cm³), slightly denser objects that would sink in fresh water can remain buoyant. A human body averages around 0.985 g/cm³ and floats more easily in the ocean than in a freshwater lake for exactly this reason.
The Material Reference Table
The reference table at the bottom of the calculator lists 24 materials across three categories: metals, liquids and gases, and construction materials. All values are in g/cm³ at standard conditions (approximately 20°C, sea level).
It serves two jobs. First, look up a material and enter its density directly without leaving the page. Second, use it to check your result makes sense. Calculate a density of 8.96 g/cm³ and the table confirms that is copper.
Density values for gases differ at altitude or in pressurised environments. Air at sea level is 0.0012 g/cm³. At cruising altitude (10,000 metres) it drops to around 0.0004 g/cm³. For solids and liquids the variation with temperature is smaller but still measurable.
Density of Common Materials
Reference values at approximately 20°C and standard atmospheric pressure (1 atm), in g/cm³. To convert to kg/m³, multiply by 1,000.
Metals
| Material | Density (g/cm³) | Density (kg/m³) |
|---|---|---|
| Osmium | 22.59 | 22,590 |
| Iridium | 22.56 | 22,560 |
| Platinum | 21.45 | 21,450 |
| Gold | 19.32 | 19,320 |
| Lead | 11.34 | 11,340 |
| Silver | 10.50 | 10,500 |
| Copper | 8.96 | 8,960 |
| Steel | 7.85 | 7,850 |
| Iron | 7.87 | 7,870 |
| Zinc | 7.14 | 7,140 |
| Aluminium | 2.70 | 2,700 |
| Magnesium | 1.74 | 1,740 |
Liquids and Gases
| Material | Density (g/cm³) | Notes |
|---|---|---|
| Mercury | 13.53 | Heaviest common liquid |
| Seawater | 1.025 | Varies with salinity |
| Water (4°C) | 1.000 | Reference density for buoyancy |
| Water (20°C) | 0.998 | Room temperature |
| Milk | 1.030 | Whole milk, approximate |
| Olive oil | 0.910 | Floats on water |
| Ethanol | 0.789 | Pure ethyl alcohol |
| Gasoline | 0.720 | Approximate, varies by blend |
| Air (sea level) | 0.00120 | Drops to ~0.0004 at 10,000 m |
Construction and Other Materials
| Material | Density (g/cm³) | Notes |
|---|---|---|
| Granite | 2.70 | Typical building stone |
| Concrete | 2.30 | Standard reinforced mix |
| Glass | 2.50 | Soda-lime glass |
| Brick | 1.90 | Standard clay brick |
| Oak Wood | 0.71 | Hardwood; floats but barely |
| Pine Wood | 0.51 | Softwood; floats comfortably |
| Ice | 0.917 | Lower than liquid water; floats |
| Foam (polyurethane) | 0.030 | Very low density; highly buoyant |
Units Supported
Mass: kg, g, mg, lb, oz, tonne (metric), US ton
Volume: m³, cm³, mm³, litre, mL, ft³, in³, US gallon
Density: kg/m³, g/cm³, g/mL, kg/L, lb/ft³, lb/in³
All conversions go through SI base units internally. Enter mass in pounds, volume in litres, and get the result in g/cm³ without any manual conversion steps.
Real-World Uses of Density
Density shows up in more fields than most people expect.
Engineering and construction. Structural engineers calculate the mass of slabs, beams, and columns from their volume and material density before a building goes up. Getting this wrong affects load calculations, foundation design, and safety margins.
Shipping and logistics. Freight carriers use density to classify shipments. The National Motor Freight Classification (NMFC) system in the US assigns freight classes partly based on density: lower-density goods take up more space and cost more to ship per kilogram. Knowing your shipment’s density before dispatch avoids reclassification charges at delivery.
Chemistry and lab work. Measuring liquid density is a standard quality check. A density reading outside the expected range signals contamination, incorrect concentration, or the wrong material entirely. It is faster than full spectroscopic analysis and requires only a scale and a graduated cylinder.
Geology. Geologists use density to classify rock and mineral samples. The Earth’s layers increase in density from the crust (around 2.7 g/cm³) to the inner core (approximately 13 g/cm³). Density contrasts between rock types drive the tectonic processes that shape the surface.
Food and beverages. Brewers and winemakers measure the density of fermenting liquid (specific gravity) to track alcohol content and fermentation progress. A hydrometer measures liquid density relative to water. The same principle applies to checking cooking oil quality or the concentration of a syrup.
Medicine. Bone mineral density (BMD) is measured to diagnose osteoporosis and assess fracture risk. Body density is used in some body composition calculations to estimate fat and lean mass percentage.
Frequently Asked Questions
What is density in simple terms?
Density measures how much mass is packed into a given space. A small heavy object has high density. A large light object has low density. Lead is dense. Foam is not.
What is the formula for density?
ρ = m ÷ V. Density equals mass divided by volume. Rearranged: mass = density × volume (m = ρ × V), and volume = mass ÷ density (V = m ÷ ρ). The SI unit for density is kg/m³. In chemistry and lab work, g/cm³ is more commonly used.
What unit is density measured in?
The SI unit is kg/m³. In chemistry and everyday science, g/cm³ is more practical. For liquids, g/mL is common since 1 g/mL equals 1 g/cm³ exactly. The imperial equivalents are lb/ft³ and lb/in³. To convert g/cm³ to kg/m³, multiply by 1,000.
What is the density of water?
Water is 1.00 g/cm³ at 4°C. At room temperature (20°C) it is approximately 0.998 g/cm³. Seawater sits around 1.025 g/cm³ due to dissolved salts. Water’s density is the reference point for all buoyancy calculations.
Why does ice float on water?
When water freezes, its molecules form a hexagonal lattice that is more spread out than liquid water. This gives ice a density of 0.917 g/cm³, lower than liquid water at 1.00 g/cm³. Lower density means it floats. This is why lakes freeze from the top down, which keeps aquatic life alive through winter.
What is the densest naturally occurring element?
Osmium, at 22.59 g/cm³. Iridium is close at 22.56 g/cm³. Both are nearly twice as dense as gold (19.32 g/cm³) and over three times denser than iron (7.87 g/cm³).
Can density be negative?
No. Mass and volume are both positive quantities, so density is always positive. If a calculation gives a negative result, check that both input values are positive and that the correct mode is selected.
How does temperature affect density?
Higher temperature generally means lower density. Molecules move faster, spread further apart, and the material expands. Water is the most notable exception: it becomes denser between 0°C and 4°C before following the normal pattern above 4°C. For gases, the effect is much larger than for solids or liquids. Air at sea level is 0.0012 g/cm³. At cruising altitude (10,000 metres) it drops to around 0.0004 g/cm³.
How do I measure the density of a liquid?
Weigh an empty container. Add the liquid and weigh again. Subtract to find the mass of the liquid. Measure the volume with a graduated cylinder. Divide mass by volume. Enter both into the Find Density mode and the calculator handles the rest.
What is specific gravity, and how does it relate to density?
Specific gravity is the ratio of a material’s density to the density of water (1.00 g/cm³ at 4°C). A specific gravity of 2.70 means the material is 2.70 times denser than water — which is aluminium. Specific gravity has no units because the density units cancel out. For solids and liquids, water is the reference. For gases, air is the reference. Specific gravity and density give the same information expressed differently.
What is the difference between mass and weight in density calculations?
Mass is the amount of matter in an object, measured in kg or grams, and does not change with location. Weight is the force gravity exerts on that mass, measured in Newtons. Density uses mass, not weight. A 1 kg object on the Moon still has a mass of 1 kg and the same density as on Earth, even though its weight is about one-sixth as much.
