Enter the mass in grams, the number of molecules, and the molar mass into the calculator to determine the missing variable.

Molecules To Gram Calculator

Pick your substance and enter a number of molecules.

Molecules → Grams
Grams → Molecules
Enter a positive number (e.g. 6.022e23).

Related Calculators

Molecules to Gram Formula

The following formula is used to calculate the mass in grams for a given number of molecules and molar mass.

m = (N * M) / N_A

Variables:

  • m is the mass in grams
  • N is the number of molecules
  • M is the molar mass in grams per mole (g/mol)
  • NA is Avogadro's number (approximately 6.02214076 × 1023 molecules per mole)

To calculate the mass in grams, multiply the number of molecules by the molar mass and then divide by Avogadro's number.

Molecules to Mass Conversion Table (Water, M = 18.01528 g/mol)
Molecules Grams (g) Kilograms (kg) Pounds (lb) Ounces (oz)
5e190.0010.0000.0000.000
1e200.0030.0000.0000.000
2e200.0060.0000.0000.000
5e200.0150.0000.0000.001
7.5e200.0220.0000.0000.001
1e210.0300.0000.0000.001
2e210.0600.0000.0000.002
5e210.1500.0000.0000.005
7.5e210.2240.0000.0000.008
1e220.2990.0000.0010.011
2.5e220.7480.0010.0020.026
5e221.4960.0010.0030.053
7.5e222.2440.0020.0050.079
1e232.9920.0030.0070.106
2.5e237.4790.0070.0160.264
5e2314.9580.0150.0330.528
6.02214076e2318.0150.0180.0400.636
7.5e2322.4360.0220.0490.792
1e2429.9150.0300.0661.055
2.5e2474.7880.0750.1652.638
* Rounded to 3 decimals. Assumes water (M = 18.01528 g/mol) and Avogadro's constant N_A = 6.02214076×10^23 mol^-1. Mass m (g) = N × M / N_A. Unit conversions: 1 kg = 1000 g, 1 lb = 453.592 g, 1 oz = 28.3495 g.

What is a Molecule?

A molecule is the smallest unit of a chemical compound that can exist. It is composed of two or more atoms that are chemically bonded together. Molecules are the building blocks of matter and can vary greatly in size and complexity. They can consist of atoms of the same element, such as O2 (oxygen gas), or different elements, such as H2O (water). Molecules are involved in chemical reactions and are essential to the structure and function of living organisms.

How to Calculate Molecules to Gram?

The following steps outline how to calculate the mass in grams from the number of molecules and molar mass.


  1. First, determine the number of molecules (N).
  2. Next, determine the molar mass (M) in grams per mole.
  3. Use Avogadro's number (NA) which is approximately 6.02214076 × 1023 molecules per mole.
  4. Calculate the mass in grams using the formula m = (N * M) / NA.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Number of molecules (N) = 1.2044 × 1024

Molar mass (M) = 18 g/mol