mmol to mg Converter
To convert mmol to mg, multiply the value in millimoles by the molecular weight (g/mol).
How to Convert mmol to mg
Use this mmol to mg converter to change millimoles into milligrams. Enter mmol and the molecular weight in g/mol.
This is the simplest moles-to-mass rule: mg = mmol × molecular weight. The factors of 1,000 in milli- cancel out.
For example, 17 mmol of sodium chloride (MW 58.44 g/mol) is 17 × 58.44 = 993.48 mg, or about 1 g.
mg = mmol × MWMultiply the millimoles by the molecular weight (g/mol) to get milligrams.Conversion Formula
The formula to convert mmol to mg is:
Where:
- mmol = amount in millimoles (10⁻³ mol)
- mg = mass in milligrams (10⁻³ g)
- MW = molecular weight (molar mass) in g/mol
Conversion Table
Common mmol to mg conversions are shown below. The last column uses sodium chloride (MW 58.44 g/mol) as an example.
| mmol | mg (formula) | mg for sodium chloride |
|---|---|---|
| 0.01 | 0.01 × MW | 0.5844 |
| 0.1 | 0.1 × MW | 5.844 |
| 0.33 | 0.33 × MW | 19.2852 |
| 0.5 | 0.5 × MW | 29.22 |
| 1 | 1 × MW | 58.44 |
| 2.5 | 2.5 × MW | 146.1 |
| 5 | 5 × MW | 292.2 |
| 10 | 10 × MW | 584.4 |
| 33 | 33 × MW | 1,928.52 |
| 50 | 50 × MW | 2,922 |
| 100 | 100 × MW | 5,844 |
| 250 | 250 × MW | 14,610 |
| 500 | 500 × MW | 29,220 |
| 1,000 | 1,000 × MW | 58,440 |
Worked Examples
Here are some common examples of mmol to mg conversion, using sodium chloride (MW 58.44 g/mol):
- 58.44 mg = 1 mmol
- 292.2 mg = 5 mmol
- 1,928.52 mg = 33 mmol
- 5,844 mg = 100 mmol
Unit Definitions
What is a millimole (mmol)?
A millimole (mmol) is a unit of amount of substance equal to 10⁻³ mole.
The prefix milli- (m) means 10⁻³, or one thousandth. So 1 mmol = 0.001 mol.
What is a milligram (mg)?
A milligram (mg) is a unit of mass equal to 10⁻³ gram.
The prefix milli- (m) means 10⁻³, or one thousandth. So 1 mg = 0.001 g.
Why Is Molecular Weight Needed?
Moles count particles. Grams measure mass. One particle of each substance has its own mass, so the link between them is the molecular weight (MW), also called molar mass.
MW tells you how many grams one mole of a substance weighs. For example, one mole of water weighs about 18.015 g, while one mole of glucose weighs about 180.16 g.
Therefore, to convert mmol to mg, you multiply by MW. Both units use the same prefix size, so no extra step is needed.
Uses and Importance of mmol and mg
mmol and mg are both everyday units in chemistry, pharmacy and nutrition. Because the prefixes match, the conversion is just mmol × MW.
Salt and electrolytes
Sodium intake can be expressed in mmol or mg. Converting helps compare nutrition labels with medical guidance.
Drug formulation
Pharmacists convert mmol of an active ingredient into mg to weigh it.
Lab reagents
Most small-scale recipes are written in mmol, while balances read in mg.
Frequently Asked Questions (FAQ)
Why is mmol to mg just × MW?
Both units have the milli- prefix. The 1,000 in the mass and the 1,000 in the amount cancel, leaving mg = mmol × MW.
How many mg are in 1 mmol of NaCl?
1 × 58.44 = 58.44 mg.
Is 1 mmol of sodium the same mass as 1 mmol of salt?
No. Sodium alone has an atomic weight of about 22.99, while sodium chloride is about 58.44. Always use the MW of what you are weighing.
Does this work for ions?
Yes. Use the atomic or ionic weight in g/mol. The mass of the lost or gained electrons is too small to matter.
What about mEq?
For ions with a charge of 1, 1 mmol = 1 mEq. For charge 2 (such as calcium), 1 mmol = 2 mEq. This page converts mmol only.
Other Related Tools
Accuracy and Scope
The result depends on the molecular or ionic weight you enter.
This tool is not a dosing calculator.
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