Peptide Dosage Calculator

This free peptide dosage calculator converts a target amount of any peptide into the exact volume and syringe units to measure. Enter the vial size, the amount of bacteriostatic water added, and your target amount in mg or mcg. The calculator handles the conversions instantly.

It is designed for researchers, students, and anyone working with lyophilized peptides who wants accurate, repeatable math. The calculator works for any peptide, because the conversion depends only on the numbers you enter, not on the compound itself. All results are for research and educational purposes only.

How many units is 1 mg?

There is no single answer, because “units” on a syringe measure volume, not the amount of peptide. One unit on a U-100 insulin syringe is always 0.01 mL. How much peptide is in that 0.01 mL depends on the concentration of your solution, which is set by the vial size and the amount of water added. The same 1 mg can be a small number of units or a large one.

Here is a worked example. At 2.5 mg/mL (for example, a 5 mg vial with 2 mL of water), 1 mg is 1 ÷ 2.5 = 0.4 mL, which is 40 units. At 5 mg/mL (a 5 mg vial with 1 mL of water, or a 10 mg vial with 2 mL), 1 mg is 1 ÷ 5 = 0.2 mL, which is 20 units. The general formula is: units = (amount in mg ÷ concentration in mg/mL) × 100.

mg to units conversion table

The table below shows how many U-100 syringe units are needed for 0.25 mg, 0.5 mg, and 1 mg at four common concentrations. Read across to your concentration to find the matching units.

Amount	1 mg/mL	2.5 mg/mL	5 mg/mL	10 mg/mL
0.25 mg (250 mcg)	25 units	10 units	5 units	2.5 units
0.5 mg (500 mcg)	50 units	20 units	10 units	5 units
1 mg (1,000 mcg)	100 units	40 units	20 units	10 units

Notice that higher concentrations need fewer units. Very small unit values, such as 2.5 units, are harder to measure accurately. This is one reason many researchers choose a concentration that gives a comfortable, whole-number reading.

How to use this calculator

Step 1: Enter the total peptide in the vial:

Check the vial label for the total amount of peptide, usually listed in milligrams (mg). Enter this number exactly. If the label shows micrograms, divide by 1,000 to get milligrams, or switch the calculator's unit selector. Every later result depends on this figure being correct.

Step 2: Enter the water volume:

Enter the number of millilitres (mL) of bacteriostatic water added to the vial. The calculator divides the peptide amount by this volume to find the concentration in mg/mL. If you haven't mixed the vial yet, you can try different water volumes here to see which one gives easy-to-measure unit values.

Step 3: Enter the target amount:

Enter the amount you want to measure and pick the correct unit, mg or mcg. Mixing these up is the most common error in peptide math, because a mcg value entered as mg is 1,000 times too large. If a result looks unusually high or low, check this field first.

Step 4: Review the volume and units:

The calculator shows the concentration, the volume in mL, and the number of units on a U-100 syringe. Compare the result with the conversion table above as a quick sanity check. If the unit value is very small or larger than your syringe holds, go back to Step 2 and try a different water volume.

Frequently asked questions

How do I convert mg to syringe units?

First find the concentration by dividing the total mg in the vial by the mL of water added. Then divide your target amount in mg by that concentration to get the volume in mL. Finally, multiply by 100 to get units on a U-100 syringe. For example, 0.5 mg at 2.5 mg/mL is 0.2 mL, which is 20 units.

What is the difference between mg, mcg and units?

Milligrams (mg) and micrograms (mcg) measure the amount of peptide, and 1 mg equals 1,000 mcg. Units measure volume on an insulin syringe, and on a U-100 syringe 1 unit equals 0.01 mL. Units only tell you how much liquid you are drawing. To know how much peptide is in that liquid, you need the concentration.

Why does the water volume change my dose in units?

The water volume doesn't change the amount of peptide you are measuring. It changes how spread out that peptide is. More water makes a weaker solution, so you need more liquid (more units) for the same amount. Less water makes a stronger solution, so you need fewer units. This is why you must always enter the actual water volume used.

What syringe size should I use?

U-100 insulin syringes come in 0.3 mL (30 units), 0.5 mL (50 units), and 1 mL (100 units) sizes. Choose one that holds your full calculated volume in a single draw. Smaller syringes usually have finer markings, which makes small volumes easier to read. Make sure the syringe is U-100, because U-40 syringes use a different scale and won't match these calculations.

All content and calculations on this page are for research and educational purposes only. Nothing here is medical advice, a treatment recommendation, or an endorsement of any product or supplier. Many peptides are not approved for human use. Always verify calculations independently, and consult a qualified healthcare professional for any question about your health.