Enter your semaglutide vial size and the volume of bacteriostatic water you are adding. The calculator returns the concentration in mcg/ml and the exact number of units to draw on a U-100 insulin syringe for your weekly dose. It works for 2mg, 5mg and 10mg vials at any titration step.
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Results
Concentration
2500 mcg/ml
2.5 mg/ml
Volume to inject
0.1 ml
per dose
Units on insulin syringe (U-100)
10 units
on a standard 100-unit insulin syringe
Doses per vial
20 doses
at 250 mcg each
How this is calculated
5mg × 1,000 = 5000 mcg total
5000 ÷ 2ml = 2500 mcg/ml
250 mcg ÷ 2500 = 0.1 ml
0.1 ml × 100 = 10 units
Disclaimer: This calculator is provided for informational purposes only. Always verify results against your specific vial labelling before use. Peptidy does not provide medical advice — consult a qualified healthcare professional before beginning or modifying any protocol. Use of research peptides may be subject to legal restrictions in your jurisdiction.
Semaglutide is a GLP-1 receptor agonist dosed once weekly, with the dose titrated upward every four weeks to limit gastrointestinal side effects. Because the maintenance dose is small relative to the vial, accurate reconstitution matters: a concentration error changes every weekly injection for the life of the vial.
The standard titration schedule used in the STEP clinical trials. Steps are held for four weeks each; escalation is slowed or paused if side effects are not tolerated.
| Weeks 1–4 (starting dose) | 0.25 mg (250 mcg) once weekly |
| Weeks 5–8 | 0.5 mg (500 mcg) once weekly |
| Weeks 9–12 | 1.0 mg (1,000 mcg) once weekly |
| Weeks 13–16 | 1.7 mg (1,700 mcg) once weekly |
| Week 17 onward (maintenance) | 2.4 mg (2,400 mcg) once weekly |
Worked example: 5mg vial + 2ml BAC water, 0.25mg starting dose
A common choice is 2ml, giving 2,500 mcg/ml. At that concentration a 0.25mg (250mcg) starting dose is 0.1ml = 10 units, and a 2.4mg maintenance dose is roughly 0.96ml = 96 units. Some people prefer 1ml of BAC water for a 5,000 mcg/ml concentration so the injection volume is halved.
It depends on your concentration. With a 5mg vial reconstituted in 2ml (2,500 mcg/ml): 250 ÷ 2,500 = 0.1ml = 10 units on a U-100 syringe. With a 5mg vial in 1ml (5,000 mcg/ml): 250 ÷ 5,000 = 0.05ml = 5 units.
At the 0.25mg starting dose a 5mg vial provides 20 weekly injections. As you titrate up the number of doses per vial falls: at 1mg weekly it lasts 5 weeks, and at the 2.4mg maintenance dose a single 5mg vial provides just over two doses. Enter your dose above to see doses-per-vial for your exact setup.
Because the maintenance dose (up to 2.4mg) is a large fraction of a 5mg or 10mg vial. If 96 units feels like too much liquid to inject, reconstitute with less BAC water to raise the concentration, or use a larger vial so the dose is a smaller share of the total volume.
Keep it refrigerated at 2–8°C, away from light, and use within the timeframe indicated by your supplier — reconstituted semaglutide in bacteriostatic water is commonly used within 4–8 weeks. Do not freeze it, and label the vial with the reconstitution date.
Store your vial concentration, log every dose against it, and never lose track of what you injected or when.