mg to ml Calculator — Convert Milligrams to Milliliters
Instantly convert between milligrams and milliliters for any concentration. Essential for peptide reconstitution, semaglutide dosing, tirzepatide dosing, and all injectable medications.
Formula: ml = mg ÷ concentration (mg/ml)
Formula: mg = ml × concentration (mg/ml)
How to use this calculator
Enter your dose in milligrams and the concentration of your reconstituted solution. The concentration is determined by how much BAC water you added to your peptide vial. For example, if you added 2 ml of BAC water to a 5 mg vial, your concentration is 2.5 mg/ml.
The result tells you exactly how many milliliters to draw into your syringe. On a standard 100-unit insulin syringe, multiply the ml value by 100 to get the unit marking (e.g., 0.4 ml = 40 units).
You can't convert mg to ml without concentration
Milligrams measure mass. Milliliters measure volume. No fixed conversion exists between the two — 5 mg of one solution fills 5 ml, while 5 mg of another fills 0.05 ml. The value that connects them is the concentration of the solution, expressed in mg per ml. Stated as a formula:
ml = mg ÷ concentration (mg/ml)
mg = ml × concentration (mg/ml)
An mg to ml answer without a stated concentration is not an answer — it is a guess about a number that was never given. The calculator above asks for concentration for this reason: once it is entered, the conversion is a single division.
mg to ml Quick Reference Table
Common conversions at three standard reconstitution concentrations. All values show the volume in ml needed to deliver the listed mg dose.
| Dose (mg) | 1 mg/ml | 2 mg/ml | 5 mg/ml |
|---|---|---|---|
| 1 mg | 1.000 ml | 0.500 ml | 0.200 ml |
| 2 mg | 2.000 ml | 1.000 ml | 0.400 ml |
| 5 mg | 5.000 ml | 2.500 ml | 1.000 ml |
| 10 mg | 10.000 ml | 5.000 ml | 2.000 ml |
| 15 mg | 15.000 ml | 7.500 ml | 3.000 ml |
| 30 mg | 30.000 ml | 15.000 ml | 6.000 ml |
Note: values above 1 ml are shown for reference. Most peptide injections use a 1 ml insulin syringe. For large volumes, a different syringe size may be needed.
ml per 1 mg and per 5 mg at common concentrations
The formula ml = mg ÷ concentration applied to the two amounts searched most often, at eight concentrations in common use.
| Concentration (mg/ml) | Volume of 1 mg | Volume of 5 mg |
|---|---|---|
| 0.5 mg/ml | 2 ml | 10 ml |
| 1 mg/ml | 1 ml | 5 ml |
| 2 mg/ml | 0.5 ml | 2.5 ml |
| 2.5 mg/ml | 0.4 ml | 2 ml |
| 5 mg/ml | 0.2 ml | 1 ml |
| 10 mg/ml | 0.1 ml | 0.5 ml |
| 50 mg/ml | 0.02 ml | 0.1 ml |
| 100 mg/ml | 0.01 ml | 0.05 ml |
Read a row across: at 2.5 mg/ml, 1 mg is 0.4 ml and 5 mg is 2 ml. For any other amount, divide by the concentration — or enter both values in the calculator above. At 50 and 100 mg/ml, 1 mg sits at or below the 0.01 ml graduation of a standard 1 ml insulin syringe.
Worked examples: 5 mg to ml at three concentrations
The same 5 mg produces three different volumes. The concentration has to come first, because it decides which answer applies.
5 mg at 1 mg/ml
5 ÷ 1 = 5 ml
Five times the capacity of a standard 1 ml insulin syringe.
5 mg at 5 mg/ml
5 ÷ 5 = 1 ml
One full 1 ml syringe, to the 100-unit mark.
5 mg at 10 mg/ml
5 ÷ 10 = 0.5 ml
Half a 1 ml syringe, to the 50-unit mark.
The same division covers every amount. 10 mg to ml works out to 10 ml at 1 mg/ml, 2 ml at 5 mg/ml, and 1 ml at 10 mg/ml. 1 mg in ml works out to 1 ml at 1 mg/ml, 0.2 ml at 5 mg/ml, and 0.1 ml at 10 mg/ml.
Two patterns follow from the formula. Ten times the mg at the same concentration is always ten times the ml. And each doubling of the concentration halves the ml for the same mg — which is why two people reconstituting the same vial differently will draw different volumes for the same dose.
Understanding mg to ml Conversions for Peptides
When working with injectable peptides, the single most important calculation you will perform is converting the milligram dose you want into the milliliter volume you draw. Unlike oral medications, injectable peptides require you to do this conversion manually — and getting it right is critical.
The key variable is concentration, expressed in mg/ml. This is not a fixed number — it changes based on how much bacteriostatic water (BAC water) you added during reconstitution. If you added 2 ml of BAC water to a 5 mg vial, the concentration is 2.5 mg/ml. If you added 1 ml instead, the concentration is 5 mg/ml and each unit of insulin syringe contains twice as much peptide.
For GLP-1 agonists like semaglutide and tirzepatide, typical research concentrations range from 2 mg/ml to 5 mg/ml depending on vial size and desired dose precision. Semaglutide is often reconstituted at 2.5 mg/ml (2 ml BAC water into 5 mg vial), while tirzepatide vials of 10 mg are frequently reconstituted with 2 ml for a 5 mg/ml concentration.
Always double-check your arithmetic before injecting. A tenfold dosing error — for example, confusing 0.1 ml with 1 ml — is one of the most common medication errors in injectable drug administration. Use this calculator every time you prepare a new vial or change your reconstitution volume.
In peptide reconstitution, you choose the concentration
Peptide vials are labeled by the mass of powder inside — 2 mg, 5 mg, 10 mg. A dry vial has no concentration, because concentration is mass dissolved per volume of liquid, and there is no liquid yet. When you add bacteriostatic (BAC) water to the vial, you set the concentration yourself: the mg on the label divided by the ml of water you added.
A 5 mg vial reconstituted with 5 ml of BAC water gives 1 mg/ml. The same vial reconstituted with 1 ml gives 5 mg/ml. The powder did not change — the concentration did, and with it the volume that each mg of peptide occupies in the syringe.
This is why reconstitution comes before any mg to ml conversion: the reconstitution step produces the concentration the conversion depends on. The reconstitution calculator works out the concentration from your vial size and BAC water volume, and what mcg per ml concentration means explains the units behind it.