How-to · Updated October 2, 2026
How do you convert mg to mL?
Direct answer
mL = mg ÷ concentration (mg/mL). For water at 1,000 mg/mL, 100 mg is 0.1 mL and 1 mg is 0.001 mL. At 20 mg/mL, 20 mg is 1 mL.
Water, 1,000 mg per mL
| Milligrams | Milliliters of water |
|---|---|
| 1 mg | 0.001 mL |
| 2.5 mg | 0.0025 mL |
| 20 mg | 0.02 mL |
| 100 mg | 0.1 mL |
| 1,000 mg | 1 mL |
1,000 mg of water is 1 mL. That is why dividing by 1,000 turns milligrams of water into milliliters.
When the concentration is not water
| Amount | Concentration | Volume |
|---|---|---|
| 20 mg | 20 mg/mL | 1 mL |
| 50 mg | 20 mg/mL | 2.5 mL |
| 100 mg | 100 mg/5 mL (20 mg/mL) | 5 mL |
Limits
- Educational conversion, not a dose and not medical advice. Use the concentration printed on the product.
- A milligram measures mass. A milliliter measures volume. The same milligram amount is a different volume in oil, milk, or a liquid medicine.
- Water’s 1,000 mg/mL figure is the density used by this calculator. It is not a medication strength.
Use the calculator
The reverse direction: how many mg are in a mL. Enter a concentration in the mg to mL calculator.