Calculate molar mass from density, volume, and moles, or solve for density, volume, or moles. Optional substance presets retain approximate reference values; use density appropriate to your sample conditions. Density alone does not determine molar mass.

Calculate mass per mole from a sample.

Density alone cannot determine molar mass. Use density, volume and amount for the same sample. Substance presets are approximate reference values; edit density for your temperature and pressure.

Optional settings

Applies the original reference density and molar mass to available inputs; sample volume and moles still require your data.

Molar Mass From Density Formula

The following formula is used to calculate the Molar Mass From Density. 

MM = (D × V × 1000) / n
  • Where MM is the Molar Mass From Density (g/mol)
  • n is the number of moles 
  • D is the density (kg/m^3) 
  • V is the volume (m^3) 

To calculate the molar mass from density, multiply the density by the volume, then multiply by 1000 and divide by the number of moles.

Density Unit Conversion Table (kg/m³ ↔ g/cm³ ↔ lb/ft³)
kg/m³ g/cm³ lb/ft³
5000.50031.214
7000.70043.700
7400.74046.197
7890.78949.256
8000.80049.942
8500.85053.064
9000.90056.185
9170.91757.246
9500.95059.307
10001.00062.428
10251.02563.989
11001.10068.671
12001.20074.914
15001.50093.642
20002.000124.856
24002.400149.827
27002.700168.555
78507.850490.059
89608.960559.355
1134011.340707.933
Conversion factors used: 1 g/cm³ = 1000 kg/m³; 1 lb/ft³ ≈ 16.018463374 kg/m³.

How to Calculate Molar Mass From Density?

The following example problems outline how to calculate Molar Mass From Density.

Example Problem #1

  1. First, determine the number of moles.
    • The number of moles is calculated to be 4.5.
  2. Next, determine the density (kg/m^3).
    • The density (kg/m^3) is measured to be 30.
  3. Next, determine the volume (m^3).
    • The volume (m^3) is found to be 300.
  4. Finally, calculate the Molar Mass From Density using the formula above: 

MM = (D*V * 1000) / n

The values given above are inserted into the equation below and the solution is calculated:

MM = (30*300 * 1000) / 4.5 = 2,000,000 (g/mol)

Example Problem #2

The variables needed for this problem are provided below:

number of moles = 6

density (kg/m^3) = 7

volume (m^3) = 4

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

MM = (D*V * 1000) / n = (g/mol)