Peptide dosing calculator
A peptide dosing calculator converts vial strength, diluent volume, dose and frequency into units per injection, doses per vial and days of supply. A 10 mg vial in 2 mL at 500 mcg twice weekly is 10 units per injection, 20 doses and about ten weeks.
From one injection to a whole schedule
Most calculators answer a single question: how many units to draw. That is the smallest part of running a protocol. The number that actually drives ordering, travel planning and refills is how long the vial in the fridge lasts at your frequency.
Enter the vial once and the planner tab does the rest — injections per vial, days of supply, and the date you should reorder so nothing lapses mid-protocol.
- Concentration (mg/mL) = vial strength (mg) ÷ bacteriostatic water (mL).
- Units per injection = (dose ÷ concentration) × 100 on a U-100 syringe.
- Injections per vial = vial strength ÷ dose, in matching units.
- Days of supply = injections per vial ÷ injections per day at your frequency.
- Reorder date = today + days of supply − your usual delivery lead time.
Supply at common dosing frequencies
Note the last row: at a low frequency the vial's beyond-use date, not the dose count, becomes the limiting factor. A reconstituted vial does not stay usable indefinitely just because peptide remains in it.
| Frequency | Injections per week | Doses per vial | Approx. supply |
|---|---|---|---|
| Daily | 7 | 20 | Under 3 weeks |
| 5 days on, 2 off | 5 | 20 | 4 weeks |
| Every other day | 3.5 | 20 | Around 6 weeks |
| Twice weekly | 2 | 20 | 10 weeks |
| Once weekly | 1 | 20 | 20 weeks — past most beyond-use dates |
What throws a dosing schedule off
- Reconstituting with a different water volume than the one used in the math, so every unit figure shifts.
- Switching syringes mid-protocol — U-40 and U-50 barrels read completely differently from U-100.
- Ignoring dead space, which quietly removes the final partial dose from most vials.
- Forgetting the reconstitution date, which makes the beyond-use date a guess.
- Counting missed injections as supply. A skipped dose extends the vial but not its shelf life.
- Ordering on the run-out date rather than ahead of delivery lead time.
Free dosing calculator
Plan your dosing schedule
Enter the vial, your dose and how often you inject. You get units per injection, doses per vial, days of supply and a suggested reorder date.
Vial supply planner
Estimate supply from the amount you entered. This does not set your schedule.
- Whole doses
- 20
- Estimated supply
- 140 days · 20 weeks
- Projected run-out
- Add a start date
- Refill reminder
- Add a start date
Frequently asked questions
- What does a peptide dosing calculator do that a reconstitution calculator does not?
- Reconstitution math stops at one injection: concentration and units to draw. A dosing calculator carries that forward across the schedule, so you also see how many injections the vial holds, how many days of supply that is at your frequency, and roughly when you need the next vial.
- How do I calculate units per injection?
- Divide vial strength in mg by diluent volume in mL for concentration. Divide your dose by that concentration for volume in mL, then multiply by 100 for units on a U-100 insulin syringe. A 10 mg vial in 2 mL is 5 mg/mL, so a 500 mcg dose is 10 units.
- How long will one vial last?
- Divide total vial strength by your dose, in matching units, to get injections per vial, then divide by how many injections you take per week. A 10 mg vial at 500 mcg twice weekly is 20 doses, or 10 weeks — before any loss to syringe dead space or the beyond-use date.
- Does splitting a dose change the total?
- No. Two 250 mcg injections and one 500 mcg injection use the same amount of peptide per day, so doses per vial stay the same in total milligrams. What changes is the number of draws, which increases dead-space loss and the chance of contaminating the stopper.
- What frequency should I enter?
- Enter the frequency you were actually told to use. The calculator converts whatever you enter — daily, five days a week, twice weekly, weekly — into supply days. It does not suggest a schedule, because frequency depends on the compound, the indication and your prescriber.
- Why does my vial run out sooner than the calculator says?
- Dead space in the syringe and needle hub retains a small volume on every draw, overfill is not guaranteed, and a reconstituted vial has a beyond-use date that can arrive before the last dose. Treat the supply figure as an upper bound, not a promise.
References & evidence
Sources cited on this page. Last reviewed September 2026. Corrections: editorial policy.
- US Pharmacopeia. General Chapter <797> Pharmaceutical Compounding — Sterile Preparations (beyond-use dating principles). https://www.usp.org/compounding/general-chapter-797
- Institute for Safe Medication Practices. ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations. https://www.ismp.org/recommendations/error-prone-abbreviations-list
- Centers for Disease Control and Prevention. Injection Safety — One and Only Campaign guidance on single-dose and multi-dose vials. https://www.cdc.gov/injection-safety/hcp/clinical-safety/
Let the schedule run itself
Save the vial once and DoseRoutine shows the syringe units for every scheduled injection, counts the doses left, warns you before the beyond-use date and reminds you to reorder.
Start free in DoseRoutineEducational reference only, not medical advice. Talk to a qualified clinician before starting, stopping or combining any peptide, supplement or medication.