Peptide Dosage Calculator

Convert mcg or mg to U-100 syringe units, and back

A free peptide dosage calculator that converts a dose you already have into exact U-100 syringe units, with a visual guide showing the fill line. It also works in reverse, turning a syringe reading back into mcg for your log. It converts the number you enter. It never works out or suggests what a dose should be.

What this peptide dosage calculator does

A prescription or a personal record usually states a peptide dose as a weight, in micrograms (mcg) or milligrams (mg). A syringe measures volume, in units. This calculator is the bridge between the two. Give it the dose, the vial size and the water added, and it tells you which mark that weight corresponds to.

It is a converter, not an adviser. The dose is always a number you enter. The tool has no information about any compound, person or condition, and it never calculates what a dose should be.

mcg to units: the conversion formula

Concentration (mg/mL) = vial size (mg) ÷ water added (mL)

Volume (mL) = dose (mg) ÷ concentration (mg/mL)

U-100 units = volume (mL) × 100

A dose in mcg is divided by 1,000 first. With arbitrary example numbers that divide cleanly, and which are not a suggested amount: a 5 mg vial with 2 mL of water is 2.5 mg/mL. 250 mcg is 0.25 mg, 0.25 ÷ 2.5 is 0.1 mL, and 0.1 × 100 is 10 units.

Units back to mcg, for your log

Record-keeping often runs the other way. You know which mark the syringe was drawn to and want to write down what that was. Switch the calculator to Units → dose and it reverses the math:

Dose (mcg) = units ÷ 100 × concentration (mg/mL) × 1,000

With the same example vial, 10 units is 0.1 mL, 0.1 × 2.5 is 0.25 mg, which is 250 mcg. The “same dose, four ways” row shows mcg, mg, mL and units together, so your log can use whichever you prefer.

Reading a U-100 syringe

A U-100 syringe is the standard insulin syringe. Its scale has 100 unit marks per millilitre, so each unit is 0.01 mL.

U-100 syringe barrel sizes
Barrel	Holds	Lines usually printed	10 units equals
0.3 mL	30 units	Every 1 unit, sometimes every ½ unit	0.1 mL
0.5 mL	50 units	Every 1 unit	0.1 mL
1 mL	100 units	Every 2 units	0.1 mL

All three share the same unit size. A smaller barrel spreads the marks further apart, which makes small volumes easier to read. Pick your barrel in the calculator and the illustration redraws to match. Syringe units are a measure of volume and are not the same as the International Units (IU) on some labels. For other scales, see the guide to U-100, U-50 and U-40 syringes.

Why the same peptide dose can be a different number of units

“How many units is my dose?” has no single answer, because units only mean something next to a concentration. The same 250 mcg example reads as 5 units at 5 mg/mL, 10 units at 2.5 mg/mL and 15 units at 1.67 mg/mL. A number of units copied from someone else’s vial does not carry over to yours.

This is why the calculator asks for the vial size and the water every time. To explore how water volume moves the reading, use the BAC water calculator. To see the concentration on its own, use the reconstitution calculator.

Limits of this tool

It does not recommend, suggest or verify any peptide dose, schedule or protocol.
It cannot tell you whether a dose is appropriate. That is a question for a licensed healthcare provider.
It does not convert International Units (IU).
It does not provide medical advice, diagnosis or treatment.

Results are for research, informational and record-keeping reference only. Read the full disclaimer, or go back to the Peptrack homepage. To keep each conversion alongside a dated dose log, get the free Peptrack app.

Peptide Dosage Calculator FAQ

What does the peptide dosage calculator do?

It converts a dose you already have into the units on a U-100 insulin syringe, using the vial size and the water added. It also works in reverse, turning a syringe reading back into mcg and mg for your records. It does not work out what a dose should be.

How do I convert mcg to units?

Divide the dose in mcg by 1,000 to get mg, divide by the concentration in mg/mL to get mL, then multiply by 100. At 2.5 mg/mL, 250 mcg is 0.25 mg, 0.25 ÷ 2.5 = 0.1 mL, and 0.1 × 100 = 10 units. These numbers illustrate the formula and are not a suggested amount.

How do I convert syringe units back to mcg?

Divide the units by 100 to get mL, multiply by the concentration in mg/mL to get mg, then multiply by 1,000 for mcg. At 2.5 mg/mL, 10 units is 0.1 mL, 0.1 × 2.5 = 0.25 mg, which is 250 mcg. Switch the calculator to “Units → dose” to do this automatically.

Why is the same peptide dose a different number of units for different people?

Because units measure volume, and the volume that holds a given dose depends on the concentration in the vial. A different vial size or a different amount of water gives a different concentration, so the same dose in mcg lands on a different mark. Units only mean something alongside the concentration.

What is a U-100 syringe?

A U-100 syringe is the standard insulin syringe. Its scale has 100 unit marks per millilitre, so each unit is 0.01 mL. It is sold in 0.3 mL (30 unit), 0.5 mL (50 unit) and 1 mL (100 unit) barrels, which all share the same unit size.

Can this calculator tell me what my peptide dose should be?

No. It has no information about any compound, person or condition and never recommends, suggests or checks a dose. It only converts the number you enter. What to take, and how much, is a decision for you and a licensed healthcare provider.

Are syringe units the same as IU?

No. Units on an insulin syringe measure volume. International Units (IU) on some product labels measure biological activity and are specific to each substance. This calculator cannot convert IU.

Is the peptide dosage calculator free?

Yes. It is fast, free and needs no sign-up. The math runs in your browser and the numbers you enter never leave your device.