Published by Peptide Protocols · Reviewed September 2026 · How we make these pages · Educational & research purposes only — not medical advice.
1 mL = 100 units on a U-100 insulin syringe. Formula: mg ÷ mL = mg/mL; (mcg ÷ 1000) ÷ mg/mL = mL; mL × 100 = units.
Units to draw on a U-100 insulin syringe for the common vial sizes and water volumes. Pick the row that matches your vial and the water you added.
| Vial + water | Concentration | 1 mg | 2 mg | 3 mg | 4 mg | 5 mg | 6 mg | 7 mg |
|---|---|---|---|---|---|---|---|---|
| 5 mg vial + 1 mL water | 5 mg/mL | 20 u | 40 u | 60 u | 80 u | 100 u | 120 u | 140 u |
| 5 mg vial + 2 mL water | 2.5 mg/mL | 40 u | 80 u | 120 u | 160 u | 200 u | 240 u | 280 u |
| 5 mg vial + 3 mL water | 1.66667 mg/mL | 60 u | 120 u | 180 u | 240 u | 300 u | 360 u | 420 u |
| 10 mg vial + 1 mL water | 10 mg/mL | 10 u | 20 u | 30 u | 40 u | 50 u | 60 u | 70 u |
| 10 mg vial + 2 mL water | 5 mg/mL | 20 u | 40 u | 60 u | 80 u | 100 u | 120 u | 140 u |
| 10 mg vial + 3 mL water | 3.33333 mg/mL | 30 u | 60 u | 90 u | 120 u | 150 u | 180 u | 210 u |
| 12 mg vial + 1 mL water | 12 mg/mL | 8 u | 17 u | 25 u | 33 u | 42 u | 50 u | 58 u |
| 12 mg vial + 2 mL water | 6 mg/mL | 17 u | 33 u | 50 u | 67 u | 83 u | 100 u | 117 u |
| 12 mg vial + 3 mL water | 4 mg/mL | 25 u | 50 u | 75 u | 100 u | 125 u | 150 u | 175 u |
| 15 mg vial + 1 mL water | 15 mg/mL | 7 u | 13 u | 20 u | 27 u | 33 u | 40 u | 47 u |
| 15 mg vial + 2 mL water | 7.5 mg/mL | 13 u | 27 u | 40 u | 53 u | 67 u | 80 u | 93 u |
| 15 mg vial + 3 mL water | 5 mg/mL | 20 u | 40 u | 60 u | 80 u | 100 u | 120 u | 140 u |
| 20 mg vial + 1 mL water | 20 mg/mL | 5 u | 10 u | 15 u | 20 u | 25 u | 30 u | 35 u |
| 20 mg vial + 2 mL water | 10 mg/mL | 10 u | 20 u | 30 u | 40 u | 50 u | 60 u | 70 u |
| 20 mg vial + 3 mL water | 6.66667 mg/mL | 15 u | 30 u | 45 u | 60 u | 75 u | 90 u | 105 u |
Worked example: a 12 mg vial with 2 mL of bacteriostatic water is 6 mg/mL. A 2 mg draw is 0.33 mL, which is 33 units. Change the water and every number on the syringe changes — which is the single most common reconstitution mistake. The full explanation is in How to Reconstitute Peptides.
There is no single right amount — the water sets the concentration, not the dose. 2 mL in a 10 mg vial gives 5 mg/mL, so a 2 mg draw is 0.4 mL (40 units). 1 mL gives 10 mg/mL and the same 2 mg is 0.2 mL (20 units). Most researchers pick a volume that makes the intended draw land on an easy-to-read line of the syringe; the chart below shows every common combination.
Divide the dose (mg) by the concentration (mg/mL) to get mL, then multiply by 100 for U-100 syringe units. The calculator above does this for any vial size and water volume.
The published Phase 2 and Phase 3 trial designs use once-weekly subcutaneous administration. This page only does the arithmetic; it is not a protocol.
We do not recommend or partner with any peptide supplier. Use the checklist instead: third-party COAs that match your batch and lot, stated purity, clear research-use labeling, real support and proper cold-chain shipping.
The supplier checklist →Educational content only. Confirm the legal status where you live before ordering anything.
The one formula, a BAC-water chart, and the 10 most-researched beginner peptides — the math done for you. Print it for the fridge.
🎁 Send me the free cheat sheet →Every cheat sheet in the shop includes the Universal Excel Logbook — it auto-calculates reconstitution and tick marks for 38+ peptides and keeps a dated record of each vial.
Browse the cheat sheets on Etsy →