Peptide Dosing Calculator
Enter your vial size, BAC water volume, and desired dose to calculate the exact draw amount and number of doses per vial. Assumes a U-100 insulin syringe.
Dosing Calculator
For U-100 insulin syringes
Visual draw guide
Concentration
2500 mcg/mL
Draw Volume
0.100 mL
Syringe Units
10.0 units
on a U-100 syringe
Doses per Vial
20
For informational purposes only. Not medical advice. Calculations assume a U-100 (100 units/mL) insulin syringe.
How to read the results
- Concentration (mcg/mL)
- How potent the solution is after reconstitution.
- Draw Volume (mL)
- The total mL to pull into the syringe for your dose.
- Syringe Units
- The marking on a U-100 insulin syringe to fill to. 100 units = 1 mL.
- Doses per Vial
- How many injections at your desired dose are in the full vial.
The peptide dosing formula
The calculator runs two steps. First it finds the concentration of your reconstituted vial, then it converts your desired dose into syringe units:
concentration (mcg/mL) = (vial mg ÷ BAC water mL) × 1000
units to draw = (dose mcg ÷ concentration) × 100
Worked example: a 5 mg vial reconstituted with 2 mL of BAC water is 2,500 mcg/mL. For a 250 mcg dose: (250 ÷ 2,500) × 100 = 10 units on a U-100 insulin syringe, or 0.1 mL. That full vial holds 20 doses at 250 mcg.
Quick reference: 5 mg vial
Units to draw on a U-100 syringe by water volume and dose.
| BAC water | Concentration | 250 mcg | 500 mcg | 1,000 mcg |
|---|---|---|---|---|
| 1 mL | 5,000 mcg/mL | 5 units | 10 units | 20 units |
| 2 mL | 2,500 mcg/mL | 10 units | 20 units | 40 units |
| 3 mL | 1,667 mcg/mL | 15 units | 30 units | 60 units |
For other vial sizes, doses, or GLP-1 protocols, use the interactive calculator above.
Frequently Asked Questions
How do I calculate how many units to draw for a peptide dose?
On a U-100 insulin syringe: (Desired dose in mcg ÷ Concentration in mcg/mL) × 100 = units to draw. Concentration = (Vial mg ÷ BAC water mL) × 1000. The Research Stack dosing calculator does this automatically.
What does U-100 mean on an insulin syringe?
U-100 means 100 units equals 1 mL. This is the standard for insulin syringes used in peptide research. So 10 units = 0.1 mL, 20 units = 0.2 mL, and so on.
How much BAC water should I add to a 5mg peptide vial?
The most common is 1–2 mL of bacteriostatic water per 5 mg vial. 2 mL gives a concentration of 2,500 mcg/mL, meaning a 250 mcg dose = 10 units on a U-100 syringe — easy to read.
How many doses are in a 5mg peptide vial at 250 mcg per dose?
A 5 mg (5,000 mcg) vial at 250 mcg per dose yields 20 doses. At 500 mcg per dose, you get 10 doses. Use the dosing calculator above to calculate for your specific protocol.
How do you draw semaglutide units on an insulin syringe?
For semaglutide, first reconstitute the vial, then divide your target dose (in mg) by the concentration (mg/mL) to get the mL to draw, and multiply by 100 for units. Example: a 5 mg vial in 2 mL BAC water is 2.5 mg/mL, so a 0.25 mg starting dose is 0.1 mL = 10 units. Enter your numbers in the calculator to confirm.
What is the difference between mg, mcg, and units in peptide dosing?
Milligrams (mg) and micrograms (mcg) measure the amount of peptide — 1 mg = 1,000 mcg. Vials are usually labeled in mg and doses are often in mcg. "Units" refers to the volume markings on a U-100 insulin syringe (100 units = 1 mL) — units are not an amount of peptide, they are how much liquid you draw. The calculator converts your dose in mcg to the correct units to draw.