Milligrams measure how much of a substance there is; millilitres measure liquid volume. The link between them is the concentration: a liquid labelled 100 mg/5 mL contains 20 mg in every millilitre.
How to use the mg to mL Calculator
- Amount of active ingredient
- Concentration: amount
- Concentration: per volume
- Every result field is editable: type into Volume and Amount of active ingredient plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the concentration as written on the label; the calculator converts it to mg per mL and divides the amount by it.
Good to know
This tool does arithmetic only. Medicine doses, especially for children, must come from the prescriber or the product label; ask a pharmacist if in doubt.
Inputs explained
| Field | What to enter |
|---|---|
| Amount of active ingredient | Units: mg, g, µg |
| Concentration: amount | Units: mg, g, µg |
| Concentration: per volume | Units: mL, L, tsp |
What each result means
- Concentration = [Concentration: amount] ÷ [Concentration: per volume]
- Volume = [Amount of active ingredient] ÷ ([Concentration: amount] ÷ [Concentration: per volume])
Example values
How the main result changes when Amount of active ingredient changes and everything else stays at the example values above:
| Amount of active ingredient (mg) | Volume (mL) |
|---|---|
| 125 | 6.25 |
| 187.5 | 9.375 |
| 250 | 12.5 |
| 312.5 | 15.625 |
| 375 | 18.75 |
| 500 | 25 |
Formula
volume (mL) = mass (mg) ÷ concentration (mg/mL)Worked example
Inputs — Amount of active ingredient: 250 mg; Concentration: amount: 100 mg; Concentration: per volume: 5 mL.
Results — Concentration = 0.02 mg/mL; Volume = 12.5 mL.
Key terms
- Concentration
- Amount of a substance per unit volume of solution, e.g. mg/mL.
Frequently asked questions
How many mL is 250 mg of a 100 mg/5 mL liquid?
12.5 mL.
Is mg/mL the same as g/L?
Yes, 1 mg/mL = 1 g/L.
Can I use this for medicine?
Only to check arithmetic. Always follow the dose prescribed and measure with the syringe or cup supplied.
What formula does the mg to mL Calculator use?
volume (mL) = mass (mg) ÷ concentration (mg/mL).