What this mg to mmol calculator does
This tool converts a mass value in milligrams (mg) to an amount of substance in millimoles (mmol). It is useful in chemistry, nutrition, and lab calculations where you need to switch between mass-based units and molar units.
You only need two inputs:
- The mass in milligrams (mg)
- The molecular weight (also called molar mass) in g/mol
Formula used
The conversion is:
mmol = mg ÷ (g/mol)
Why it works: converting mg to g and mol to mmol introduces factors of 1000 that cancel out, leaving this convenient simplified formula.
Example
Convert 90 mg of glucose to mmol, using glucose molecular weight 180.156 g/mol:
90 ÷ 180.156 = 0.4996 mmol (approximately 0.5 mmol)
Common molecular weights you can use
- Glucose: 180.156 g/mol
- Cholesterol: 386.654 g/mol
- Creatinine: 113.12 g/mol
- Urea: 60.06 g/mol
- Uric acid: 168.11 g/mol
- Calcium: 40.078 g/mol
If your compound is different, enter its exact molecular weight from a trusted reference.
Important note about blood test units
Many clinical labs report values in mg/dL and mmol/L, which is a different conversion than pure mg to mmol. For blood concentration conversion, volume units also matter. This calculator is for total mass to total amount of substance, not concentration per volume.
Tips for accurate results
1) Use the correct molecular form
Some substances exist in hydrated or salt forms. Make sure the molecular weight matches the exact form you are converting.
2) Keep significant figures reasonable
Most practical conversions are fine with 3–6 decimal places.
3) Double-check units
Do not mix mg with g, or mmol with mol, without proper conversion.
Quick FAQ
Can I convert mmol back to mg?
Yes. Rearranging the equation gives: mg = mmol × (g/mol).
Is this calculator medical advice?
No. It is an educational conversion tool only. For medical decisions, rely on your healthcare provider and official lab guidance.