Density Unit Calculator & Converter

This density unit calculator converts a density value between common units such as kg/m³, g/cm³, lb/ft³, and others. You enter a number and select the unit you have, then choose the target unit; the calculator returns the converted density instantly. It also shows the conversion factor used, so you can verify the math yourself.

Formula

The conversion uses a simple ratio: multiply the input value by the conversion factor of the “from” unit (relative to kg/m³) and divide by the conversion factor of the “to” unit. In symbols:

Converted value = input × (factor_from / factor_to)

Each factor is the number of kg/m³ that equals one of that unit. For example, 1 g/cm³ = 1000 kg/m³, so the factor is 1000. For lb/ft³, 1 lb/ft³ ≈ 16.018463 kg/m³.

Worked Example

Using the defaults: input = 1, from = kg/m³ (factor 1), to = g/cm³ (factor 1000).

1. Converted value = 1 × (1 / 1000) = 0.001
2. So 1 kg/m³ equals 0.001 g/cm³.

The calculator displays 0.001 with 6 decimal places, matching this result.

What Is Density?

Density is mass per unit volume. It tells you how much matter is packed into a given space. The SI unit is kilograms per cubic meter (kg/m³), but many fields use grams per cubic centimeter (g/cm³) because it gives convenient numbers for solids and liquids. Water at 4°C has a density of about 1000 kg/m³ or 1 g/cm³.

How to Use the Calculator

• Enter the numeric density value in the first field.
• Select the unit you currently have from the “From unit” dropdown.
• Select the unit you want to convert to from the “To unit” dropdown.
• Read the converted value. The result is rounded to 6 decimal places.

You can change the value to any non-negative number. The calculator works for all common density units, including metric and imperial.

Common Unit Relationships

Here are the key conversion factors you will encounter:

• 1 g/cm³ = 1000 kg/m³ (exactly)
• 1 g/mL = 1 g/cm³ (same value)
• 1 kg/L = 1000 kg/m³ (same as g/cm³)
• 1 lb/ft³ ≈ 16.0185 kg/m³
• 1 lb/in³ ≈ 27,679.9 kg/m³
• 1 oz/in³ ≈ 1,729.99 kg/m³
• 1 slug/ft³ ≈ 515.379 kg/m³

Notice that g/cm³, g/mL, and kg/L are numerically identical because 1 cm³ = 1 mL and 1 g = 0.001 kg, 1 L = 1000 cm³.

Why Convert Density?

Density conversion is needed when combining data from different sources. For example, a materials datasheet might list density in g/cm³, but a simulation software expects kg/m³. Engineers converting a design from imperial to metric units must convert densities to keep calculations consistent. In chemistry, molarity calculations often require density in g/mL. Without correct conversion, results can be off by a factor of 1000 or more.

Common Mistakes and Pitfalls

• Confusing g/cm³ with kg/m³: they differ by a factor of 1000, a frequent error.
• Assuming g/mL equals kg/L: they are equal, but both are 1000 times larger than kg/m³.
• Mixing up lb/ft³ and lb/in³: the latter is 1728 times larger (since 1 ft = 12 in, cubed).
• Forgetting that density depends on temperature: most materials expand when heated, so density decreases. Always note the temperature at which the density was measured.

Limits of the Formula

The conversion formula is exact for the defined relationships. However, the values you enter are only as accurate as the source. Density values in tables are usually given at a specific temperature (often 20°C or 4°C for water). If you convert a density measured at one temperature to another unit, the temperature remains the same; the conversion does not adjust for thermal expansion. For gases, density is strongly affected by pressure and temperature, so always use the conditions that match your application.

Frequently Asked Questions

How do I convert g/cm³ to kg/m³?
Multiply by 1000. For example, 2.7 g/cm³ × 1000 = 2700 kg/m³. This is a common conversion for metals and minerals.

Is g/mL the same as g/cm³?
Yes, exactly. One milliliter is defined as one cubic centimeter, so the numerical density is identical. This is why water has a density of 1 g/mL and 1 g/cm³.

What is the density of water in all common units?
At 4°C, water has a density of 1000 kg/m³, 1 g/cm³, 1 g/mL, 1 kg/L, and approximately 62.428 lb/ft³. The lb/ft³ value is approximate because it depends on the exact definition of the pound.

Why do some densities have no units?
Sometimes you see “specific gravity” (SG) which is the ratio of a material’s density to the density of water. Since it is a ratio, it is dimensionless. For example, aluminum has SG ≈ 2.7, meaning it is 2.7 times denser than water. To convert SG to kg/m³, multiply by 1000.

Can I convert density to specific weight?
Yes, specific weight (weight density) is density times gravitational acceleration. In SI, multiply kg/m³ by 9.80665 m/s² to get N/m³. In imperial, multiply lb/ft³ by 32.174 ft/s² to get lbf/ft³. This calculator does not do that, but the relationship is straightforward.

What is the difference between density and viscosity?
Density measures mass per volume; viscosity measures resistance to flow. They are different physical properties. Sometimes people confuse them because both are used in fluid mechanics. This calculator only handles density.

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in v | Value | - | 1 | 0
sel from | From unit | kg/m³=1, g/cm³=1000, g/mL=1000, kg/L=1000, lb/ft³=16.018463, lb/in³=27679.905, oz/in³=1729.994, slug/ft³=515.3788184
sel to | To unit | kg/m³=1, g/cm³=1000, g/mL=1000, kg/L=1000, lb/ft³=16.018463, lb/in³=27679.905, oz/in³=1729.994, slug/ft³=515.3788184
out result | Converted value | - | v * from / to | 6