Tools › Dosing calculator
Milligrams → syringe units · Water to add · Vials per run
Your vial is labelled in milligrams. Your syringe is marked in units. They are not the same thing, and the gap between them is where almost every dosing mistake starts. This works it out for you.
Open the Protocol Builder →Pick a compound and a goal, and it returns the dose, the units to draw, how much water to add, the day-by-day schedule, and how many vials the whole run takes. Free, no account needed.A vial of peptide arrives as a dry powder. The label tells you how many milligrams are inside — but not how much liquid to add, and not how far up the syringe to pull. Those depend on a choice you make: how much bacteriostatic water you put in.
Add more water and the same dose sits further up the barrel. Add less and it sits lower. The powder does not change. The mixture does. That is why two people with identical vials can correctly draw to completely different marks.
The arithmetic itself is not hard. It is just easy to get wrong at eleven at night, holding a syringe, on your first go.
Take a 10 mg vial, and a dose of 0.5 mg.
| Step | Working | Result |
|---|---|---|
| Add bacteriostatic water | 2 ml into a 10 mg vial | 2 ml |
| Concentration | 10 mg ÷ 2 ml | 5 mg/ml |
| Dose as a volume | 0.5 mg ÷ 5 mg/ml | 0.1 ml |
| Units on a U-100 syringe | 0.1 ml × 100 | 10 units |
A U-100 syringe is marked so that 100 units is one millilitre. That single fact is what converts a volume into a mark on the barrel.
Add the water slowly down the inside of the glass and roll it — never shake it. Keep it in the fridge at 2–8 °C once mixed.
This is the question that catches people out, and it is the reason the calculator exists rather than a scrap of paper. A dose that steps up over the first few weeks does not use the same amount every week, so you cannot simply multiply.
The builder totals the actual milligrams across every week of your run, divides by what is in a vial, and tells you the number to buy — and roughly how long one vial lasts at your dose. If a larger vial would work out cheaper per milligram, it says so.
It does not diagnose anything, it does not know your medical history, and it is not a substitute for talking to somebody. It takes the dosing information we publish for each compound and does the arithmetic on it.
Every number it returns comes from the same dosing database that our compound guides read from, so the two can never disagree with each other. If something changes there, it changes in both places at once.
If you would rather just ask a person, that is what we are here for. There is no charge for it and no obligation to buy anything.
If you know what you are taking, open the builder and it will do the rest. If you do not, start with the guides — each one covers what the compound is, the dose most people land on, how it feels, and how long to run it.