Free converters & iv tool
mg to mL Calculator (and mL to mg)
To convert mg to mL you need the concentration. Divide the milligrams by the concentration in mg/mL: 10 mg of a 5 mg/mL solution is 10 ÷ 5 = 2 mL. To convert mL to mg, multiply the volume by the concentration. Without a concentration the conversion is not possible, because mg measures weight and mL measures volume.
Prepared by Prospyr · Reviewed October 3, 2026 · Free, no sign-up, runs in your browser
Read it from the vial or package label.
Volume of solution
1mL
Concentration used: 10 mg/mL (10,000 mcg/mL, 1% w/v).
A math aid. It does not suggest any dose. Confirm the concentration against the product label and your protocol; dosing decisions belong to the treating provider.
At 10 mg/mL
1 mg
0.1 mL
2 mg
0.2 mL
5 mg
0.5 mL
10 mg
1 mL
25 mg
2.5 mL
50 mg
5 mL
100 mg
10 mL
250 mg
25 mL
Why mg to mL needs a concentration
A milligram is a unit of mass. A milliliter is a unit of volume. Water happens to weigh about 1 gram per mL, but that is not true of other liquids, and a drug dissolved in a vial is described by how much is dissolved, not by what the liquid weighs. The concentration, written as mg/mL, is the link between the two.
Concentration is amount per volume: mg/mL = mg ÷ mL. Rearranged, that gives both directions.
- mg to mL: mL = mg ÷ (mg/mL)
- mL to mg: mg = mL × (mg/mL)
- Concentration from the label: mg/mL = total mg ÷ total mL
- Percent (w/v) to mg/mL: mg/mL = % × 10
Worked examples: mg to mL and mL to mg
| Question | Math | Answer |
|---|---|---|
| 10 mg at 5 mg/mL | 10 ÷ 5 | 2 mL |
| 50 mg at 20 mg/mL | 50 ÷ 20 | 2.5 mL |
| 3 mL at 10 mg/mL | 3 × 10 | 30 mg |
| 200 mcg at 5 mg/mL | 0.2 mg ÷ 5 | 0.04 mL |
| 1% solution | 1 × 10 | 10 mg/mL |
| 500 mg in 10 mL | 500 ÷ 10 | 50 mg/mL |
The numbers above are arithmetic examples only. They are not doses or recommendations.
ml to mg calculator: going the other way
Switch the direction to “mL to mg” to find how much substance is in a given volume. This is the check to run when you want to confirm the amount a syringe holds, for example. Pick the unit you want the answer in (mg, mcg or g), and the calculator converts for you.
Need to change the amount itself between mg and mcg first? Use the mg to mcg converter. If you are diluting a stock to a weaker strength, the dilution calculator does C1V1 = C2V2.
Where this fits in a practice
Practices that handle injectable products read concentrations off labels every day. A quick check that the amount and the volume agree is cheap, and the result belongs in the chart next to the order. Prospyr's charting and inventory management keep treatment amounts and product lots with the visit.
Frequently asked questions
How do you convert mg to mL?
Divide the milligrams by the concentration in mg/mL. If a solution is 20 mg/mL and you need 50 mg, the volume is 50 ÷ 20 = 2.5 mL. The concentration is printed on the vial or package label.
Can you convert mg to mL without the concentration?
No. Milligrams measure mass and milliliters measure volume, and how much mass fits in a milliliter depends on the substance and how strong the solution is. You need the concentration, or the total mg and the total mL, to convert.
How do you convert mL to mg?
Multiply the volume in mL by the concentration in mg/mL. 2.5 mL of a 20 mg/mL solution contains 2.5 × 20 = 50 mg.
What does mg/mL mean?
It is the concentration: how many milligrams of the substance are dissolved in each milliliter of solution. A 10 mg/mL solution has 10 mg in every 1 mL, so 5 mL holds 50 mg.
How do I use a percent strength like 1%?
For a weight-in-volume (w/v) percentage, 1% means 1 gram per 100 mL, which is 10 mg/mL. So a 2% solution is 20 mg/mL and a 0.5% solution is 5 mg/mL. The calculator has a percent option that does this step for you.
What if the label gives total mg in a total volume?
Divide the total mg by the total mL to get mg/mL. A vial with 500 mg in 10 mL is 500 ÷ 10 = 50 mg/mL. Choose the 'Total mg in a total volume' option and the calculator does it.
Does this calculator tell me how much of a drug to give?
No. It only converts between an amount and a volume at a concentration you enter. Which drug, which dose and which concentration to use are decisions for the treating provider, and the product label is the source for the concentration.
Sources and scope
- OpenStax, Chemistry 2e, section 3.3: Molarity (Feb 14, 2019)
Concentration as the amount of solute per volume of solution. This tool uses the mass version (mg per mL).
- NIST: Metric (SI) Prefixes
Definitions of milli and micro used in the mg, mcg and mL conversions.
A math aid, not medical advice. It uses only the concentration you enter and suggests no drug, dose or concentration. Confirm against the product label and your protocol; dosing decisions belong to the treating provider.