🧪 Density Converter: kg/m³ to g/cm³, lb/ft³ and More
By Shihab Mia · Updated 2026-07-08
Type in any box and every other unit updates instantly.
To convert density, multiply your value by the source unit factor to reach kilograms per cubic metre, then divide by the target factor. This density converter does that for you: type a number into any field, such as kilograms per cubic metre or grams per cubic centimetre, and every other unit updates at once. Water is the handy anchor at 1000 kg/m³, which equals 1 g/cm³, 1 g/ml, or about 62.43 lb/ft³. It is built for students, engineers, chemists, and anyone reconciling material data sheets that mix metric and imperial units.
What is the Density Converter?
Density is how much mass is packed into a given volume, written as mass divided by volume. A unit like kilograms per cubic metre tells you how many kilograms one cubic metre of a substance weighs. Water, for instance, has a density of about 1000 kilograms per cubic metre, which is the same as 1 gram per cubic centimetre. Because density combines a mass unit and a volume unit, there are many ways to express the same physical value, and that is exactly where a converter saves time and prevents slips.
The clean way to convert density is to pick one base unit and route every value through it. This tool uses kilograms per cubic metre (kg/m³), the SI unit, as the base. Each supported unit has a fixed factor that turns it into the base, so a conversion is two steps: multiply your input by its factor to reach kg/m³, then divide by the target factor to reach the unit you want. Grams per cubic centimetre and grams per millilitre share the same factor of 1000 because one millilitre is defined as exactly one cubic centimetre, so those two units are numerically identical.
Mixing metric and imperial density units is a frequent source of error on engineering drawings and material specifications. A pound per cubic foot is roughly 16.02 kilograms per cubic metre, while a pound per cubic inch is a far denser figure of about 27680 kilograms per cubic metre, because a cubic inch is a tiny volume (a cubic foot holds 1728 cubic inches). Converting by hand invites mistakes with powers of ten, so letting the tool hold the exact factors keeps results consistent across a whole document.
Density is closely tied to specific gravity, also called relative density. Specific gravity is a substance density divided by the density of water, so it is a dimensionless ratio. Because water is about 1 g/cm³, the specific gravity of a material is numerically equal to its density expressed in g/cm³. Steel at 7850 kg/m³ has a specific gravity of about 7.85, meaning it is roughly 7.85 times as dense as water. This is why g/cm³ is such a popular unit: the number doubles as an at-a-glance ratio against water.
Density is not perfectly constant, because it depends on temperature and, for gases, pressure. Most solids and liquids expand slightly when heated, so they become a little less dense. Water is a famous exception near freezing: it is densest at about 4°C (1000 kg/m³) and slightly less dense at 0°C and at 20°C (about 998 kg/m³), which is why ice floats. For everyday conversions the room-temperature value is fine, but for precise lab or process work you should note the temperature at which a density was measured. Gases are far more sensitive, since their density scales with pressure and inversely with absolute temperature.
Beyond the five units in this converter, engineering and physics use others you may meet on data sheets. The slug per cubic foot (slug/ft³) appears in US fluid mechanics and equals about 515.38 kg/m³; water is roughly 1.94 slug/ft³. You may also see grams per litre (g/L), pounds per US gallon, or ounces per cubic inch. All of them ultimately describe the same quantity, mass over volume, and all can be routed through kg/m³, which is why anchoring on a single base unit is the reliable strategy.
When to use it
- Comparing a material data sheet that lists density in g/cm³ with a spec given in kg/m³.
- Converting a US engineering value in pounds per cubic foot into metric units for a report.
- Checking a chemistry result in grams per millilitre against a textbook value in kg/m³.
- Reading off the specific gravity of a metal or plastic directly from its density in g/cm³.
- Estimating the mass of a part by multiplying its known volume by a converted density.
- Reconciling supplier figures in lb/in³ with an in-house standard in kg/m³ on a drawing.
How to use the Density Converter
- Find the unit your known density is in, such as kg/m³, g/cm³, or lb/ft³.
- Type the value into that field.
- Read the converted result instantly from any of the other unit fields.
- Cross-check against the material chart below if you want a sanity check.
- Clear the field or type a new number to start another conversion.
Formula & method
Worked examples
Convert 2.7 g/cm³ (the density of aluminium) into kg/m³.
- g/cm³ factor to base = 1000
- to base: 2.7 × 1000 = 2700 kg/m³
- target is kg/m³ (factor 1), so divide by 1
Result: 2.7 g/cm³ = 2700 kg/m³
Convert 62.4 lb/ft³ (about the density of water) into kg/m³.
- lb/ft³ factor to base = 16.018463
- to base: 62.4 × 16.018463 = 999.55 kg/m³
- target is kg/m³, so the result stays in kg/m³
Result: 62.4 lb/ft³ ≈ 999.5 kg/m³ (close to water at 1000)
Convert 1000 kg/m³ into g/cm³.
- source is kg/m³ (factor 1), so base value = 1000
- g/cm³ factor to base = 1000
- result = 1000 ÷ 1000 = 1
Result: 1000 kg/m³ = 1 g/cm³
Convert 7850 kg/m³ (structural steel) into lb/ft³.
- source is kg/m³, so base value = 7850
- lb/ft³ factor to base = 16.018463
- result = 7850 ÷ 16.018463 = 490.06 lb/ft³
Result: 7850 kg/m³ ≈ 490.1 lb/ft³
Conversion factors used by this tool (multiply by this to reach kg/m³)
| Unit | Factor to kg/m³ |
|---|---|
| Kilograms per cubic metre (kg/m³) | 1 |
| Grams per cubic centimetre (g/cm³) | 1000 |
| Grams per millilitre (g/ml) | 1000 |
| Pounds per cubic foot (lb/ft³) | 16.018463 |
| Pounds per cubic inch (lb/in³) | 27679.905 |
Other density units you may meet (multiply by this to reach kg/m³)
| Unit | Factor to kg/m³ |
|---|---|
| Grams per litre (g/L) | 1 |
| Milligrams per millilitre (mg/ml) | 1 |
| Kilograms per litre (kg/L) | 1000 |
| Ounces per cubic inch (oz/in³) | 1729.994 |
| Slug per cubic foot (slug/ft³) | 515.378818 |
| Pounds per US gallon (lb/US gal) | 119.826427 |
Approximate density of common materials
| Material | Density (kg/m³) | Density (g/cm³) | Density (lb/ft³) |
|---|---|---|---|
| Air (sea level, 15°C) | 1.2 | 0.0012 | 0.075 |
| Cork | 240 | 0.24 | 15 |
| Ice (0°C) | 917 | 0.917 | 57.2 |
| Water (4°C) | 1000 | 1.00 | 62.43 |
| Concrete | 2400 | 2.40 | 150 |
| Aluminium | 2700 | 2.70 | 169 |
| Steel | 7850 | 7.85 | 490 |
| Copper | 8960 | 8.96 | 559 |
| Lead | 11340 | 11.34 | 708 |
| Gold | 19300 | 19.30 | 1205 |
Common mistakes to avoid
- Confusing g/cm³ with kg/m³ by a factor of 1000. One gram per cubic centimetre equals 1000 kilograms per cubic metre, not 1. Dropping the factor of 1000 is the most frequent density slip, so let the tool handle it.
- Treating pounds per cubic inch like pounds per cubic foot. A cubic inch is far smaller than a cubic foot, so lb/in³ is about 1728 times denser than lb/ft³. Using the wrong one throws the result off by orders of magnitude.
- Assuming g/ml differs from g/cm³. A millilitre is defined as exactly one cubic centimetre, so grams per millilitre and grams per cubic centimetre are the same number. No extra conversion is needed between them.
- Confusing mass density with weight density. Density is mass over volume. Specific weight, used in some US engineering work, is force over volume and folds in gravity. Do not mix a lbf-based figure with a lbm-based one.
- Ignoring the temperature a density was measured at. Solids and liquids expand and get less dense as they warm, so a precise density should cite a temperature. Water is densest near 4°C, which is why reference values pick that point.
- Mixing up density with specific gravity. Specific gravity is density divided by the density of water, so it is a unitless ratio. It only equals the density number when that density is expressed in g/cm³.
Glossary
- Density
- Mass divided by volume. It measures how much matter is packed into a given amount of space.
- Base unit
- The single reference unit a converter routes every value through. Here it is kilograms per cubic metre.
- Conversion factor
- A fixed multiplier that turns one unit into another. Each density unit has a factor to the base unit.
- Specific gravity
- A density compared to water, also called relative density. It is dimensionless and equals the density in g/cm³, since water is about 1 g/cm³.
- Specific weight
- Weight (force) per unit volume, equal to density times gravity. It differs from mass density and is common in US fluid mechanics.
- Slug
- The unit of mass in the US customary system. One slug per cubic foot is about 515.4 kg/m³.
- SI unit
- The International System reference unit for a quantity. For density it is the kilogram per cubic metre (kg/m³).
- Molar volume
- The volume one mole of a substance occupies. Combined with molar mass it gives density, linking chemistry data to physical density.
Frequently asked questions
How do I convert kg/m³ to g/cm³?
Divide the kg/m³ value by 1000. For example, 2700 kg/m³ divided by 1000 is 2.7 g/cm³. This tool does it instantly when you type in either field.
How do I convert g/cm³ to kg/m³?
Multiply the g/cm³ value by 1000. For example, 7.85 g/cm³ times 1000 is 7850 kg/m³. It is the reverse of the kg/m³ to g/cm³ step.
Is g/ml the same as g/cm³?
Yes. One millilitre is defined as exactly one cubic centimetre, so a value in grams per millilitre is numerically identical to the same value in grams per cubic centimetre.
What is the density of water in these units?
Water at 4°C is about 1000 kg/m³, which equals 1 g/cm³, 1 g/ml, or roughly 62.43 lb/ft³. It is the most common reference point for density.
How many kg/m³ are in one lb/ft³?
One pound per cubic foot equals about 16.018463 kilograms per cubic metre. So to convert lb/ft³ to kg/m³ you multiply by roughly 16.02.
How do I convert kg/m³ to lb/ft³?
Multiply the kg/m³ value by about 0.062428, or divide by 16.018463. For example, 7850 kg/m³ is about 490 lb/ft³.
Why is lb/in³ such a large number in kg/m³?
A cubic inch is a very small volume, so packing one pound into it gives a high density. One lb/in³ is about 27680 kg/m³, far more than one lb/ft³.
What is the difference between density and specific gravity?
Specific gravity is density divided by the density of water, so it is a unitless ratio, while density carries units like kg/m³. Because water is about 1 g/cm³, specific gravity matches the density value in g/cm³.
Does density change with temperature?
Yes, slightly for solids and liquids and strongly for gases. Warming most materials makes them expand and become a little less dense, which is why precise densities cite a temperature.
Does this density converter work offline?
Yes. All calculations run in your browser with vanilla JavaScript. Once the page has loaded there is no network call, so it keeps working without a connection.