Calculate mass in grams from mmol and molar mass, or solve for amount or molar mass with μmol, mmol, mol, mg, g, kg and g/mol units.

Pick a compound to fill its molar mass, or leave on Custom and type your own.

Sum of atomic weights of the compound. Use the compound list above to auto-fill common values.

mmol ↔ grams Conversion Table (NaCl, M = 58.44 g/mol)
mmol to grams grams to mmol
0.1 mmol = 0.00584 g0.01 g = 0.171 mmol
0.25 mmol = 0.01461 g0.02 g = 0.342 mmol
0.5 mmol = 0.02922 g0.05 g = 0.856 mmol
1 mmol = 0.05844 g0.1 g = 1.711 mmol
2 mmol = 0.1169 g0.25 g = 4.278 mmol
5 mmol = 0.2922 g0.5 g = 8.556 mmol
10 mmol = 0.5844 g1 g = 17.11 mmol
25 mmol = 1.461 g2 g = 34.22 mmol
50 mmol = 2.922 g5 g = 85.56 mmol
100 mmol = 5.844 g10 g = 171.1 mmol
Formulas: grams = (mmol × M) ÷ 1000 and mmol = (grams × 1000) ÷ M. Table assumes NaCl molar mass M = 58.44 g/mol.
mmol ↔ grams Conversion Table (Glucose, M = 180.16 g/mol)
mmol to grams grams to mmol
0.1 mmol = 0.01802 g0.02 g = 0.111 mmol
0.25 mmol = 0.04504 g0.05 g = 0.277 mmol
0.5 mmol = 0.09008 g0.1 g = 0.555 mmol
1 mmol = 0.1802 g0.2 g = 1.110 mmol
2 mmol = 0.3603 g0.5 g = 2.775 mmol
5 mmol = 0.9008 g1 g = 5.550 mmol
10 mmol = 1.802 g2 g = 11.10 mmol
20 mmol = 3.603 g5 g = 27.75 mmol
50 mmol = 9.008 g10 g = 55.50 mmol
100 mmol = 18.02 g20 g = 111.0 mmol
Formulas: grams = (mmol × M) ÷ 1000 and mmol = (grams × 1000) ÷ M. Table assumes glucose molar mass M = 180.16 g/mol.

mmol to Grams Formula

The amount in millimoles is turned into a mass using the molar mass of the substance:

grams = mmol * M / 1000

The calculator rearranges the same relationship to solve for the amount or the molar mass instead:

mmol = grams * 1000 / M
M = grams * 1000 / mmol

Variables:

  • grams is the mass of the sample (g)
  • mmol is the amount of substance (millimoles)
  • M is the molar mass of the substance (g/mol)
  • 1000 is the number of millimoles in one mole, which links mmol to grams

Set “Solve for” to Mass in grams to turn an amount into a weight, to Amount in mmol to find how many millimoles a given weight contains, or to Molar mass when you already know the amount and the mass. The compound list fills the molar mass field with common values, so you do not have to add up atomic weights by hand. The unit menus let you enter umol, mmol, or mol for the amount and ug, mg, g, or kg for the mass.

Common Molar Masses and Conversion Reference

The molar mass sets the size of every mmol to grams conversion. These are the values used by the compound list in the calculator.

CompoundFormulaMolar mass (g/mol)
WaterH2O18.02
Sodium chlorideNaCl58.44
GlucoseC6H12O6180.16
SucroseC12H22O11342.30
Sodium hydroxideNaOH40.00
Sodium bicarbonateNaHCO384.01
Potassium chlorideKCl74.55
Calcium carbonateCaCO3100.09
Hydrochloric acidHCl36.46
Sulfuric acidH2SO498.08
Acetic acidCH3COOH60.05
EthanolC2H5OH46.07

This table shows the grams produced by a given number of millimoles for two common compounds, so you can check the calculator against a known value.

Amount (mmol)NaCl (58.44 g/mol)Glucose (180.16 g/mol)
10.05844 g0.1802 g
20.1169 g0.3603 g
50.2922 g0.9008 g
100.5844 g1.802 g
251.461 g4.504 g
502.922 g9.008 g
1005.844 g18.02 g

Example Problems

Example 1: mmol to grams. You have 5 mmol of glucose, which has a molar mass of 180.16 g/mol. Multiply the amount by the molar mass and divide by 1000: grams = 5 * 180.16 / 1000 = 0.9008 g. So 5 mmol of glucose weighs about 0.9 g.

Example 2: grams to mmol. You weigh out 10 g of sodium chloride (NaCl), molar mass 58.44 g/mol, and want the amount in millimoles: mmol = 10 * 1000 / 58.44 = 171.1 mmol. Set “Solve for” to Amount in mmol to get this result directly.

FAQ

Do you need the molar mass to convert mmol to grams?
Yes. Millimoles count particles, while grams measure mass, so you need the molar mass of the specific substance to move between them. Two samples with the same number of millimoles weigh different amounts when their molar masses differ.

How do you get milligrams instead of grams?
Milligrams come from the amount without the divide by 1000, since mg = mmol * M. You can also read the milligram value from the results table, or set the mass unit to mg when you solve for the amount.

Is mmol the same as millimolar (mM)?
No. A millimole (mmol) is an amount of substance. Millimolar (mM) is a concentration, equal to millimoles per liter. To turn mM into grams you first multiply by the solution volume in liters to get mmol, then convert that amount to grams with the molar mass.