GLP-1 units calculator: mg to syringe units
For planning and record-keeping only — not medical advice. Your dose and schedule are set by your prescriber.
A 2.5 mg dose of tirzepatide at a typical vial concentration of 10 mg/mL comes to 25 units on a U-100 insulin syringe. This calculator runs that conversion for any dose and concentration — and, if you're starting from a dry vial and bacteriostatic water, works out the concentration first.
Mg to units
Use this half when the concentration is already known — it's printed on the label of a pre-mixed vial, or you calculated it below. Both fields are required; the result shows syringe units and the volume they correspond to.
0 units = 0 mL on a U-100 syringe
More than 100 units — that volume doesn't fit a single 1 mL U-100 syringe.
Double-check with your pharmacist — a misread concentration changes the entire calculation.
Enter positive numbers only — zero or negative values can't be converted.
If your vial started dry
A powder vial has no concentration until you add water, so there is nothing to convert yet. Enter the milligrams printed on the vial and the millilitres you added, and this second panel returns the mg/mL — feed that back into the calculator above. Choosing the water volume in the first place is a different question, and the reconstitution calculator is built for it: it works backwards from the unit count you want per dose.
0 mg/mL after reconstitution
Your dose: 0 units (0 mL)
More than 100 units — that volume doesn't fit a single 1 mL U-100 syringe.
Double-check with your pharmacist — a misread concentration changes the entire calculation.
Enter positive numbers only — zero or negative values can't be converted.
units = mg ÷ (mg/mL) × 100
KeepAlong — GLP-1 shot tracker & planning tools
There's no dose calculator inside the KeepAlong app — Apple's health guidelines rule that out, so the math stays here on the web. What the app does is log every injection with its dose and remind you when the next shot is due.
The app is launching soon. The web tools on this site are free — no sign-up needed.
Common doses converted to units
All conversions assume a standard U-100 insulin syringe — 100 units per milliliter, the scale described in the NIH overview of insulin syringes (checked 2026-08-18). The three concentrations are the ones that come up most in practice: 5 mg/mL is a 5 mg vial reconstituted with 1 mL of water; 10 mg/mL is 10 mg + 1 mL or a 17 mg vial + 1.7 mL; 17 mg/mL is that same 17 mg vial + 1 mL. Same vial, different water volume, different concentration — which is why the mg/mL figure matters more than the number on the vial.
| Dose | At 5 mg/mL | At 10 mg/mL | At 17 mg/mL |
|---|---|---|---|
| 2.5 mg | 50 units (0.5 mL) | 25 units (0.25 mL) | 14.7 units (0.15 mL) |
| 5 mg | 100 units (1 mL) | 50 units (0.5 mL) | 29.4 units (0.29 mL) |
| 7.5 mg | 150 units (1.5 mL)* | 75 units (0.75 mL) | 44.1 units (0.44 mL) |
| 10 mg | 200 units (2 mL)* | 100 units (1 mL) | 58.8 units (0.59 mL) |
* More than one full 1 mL U-100 syringe — a single draw can't hold that volume.
Who actually needs this math
People injecting from a vial. Compounded semaglutide and tirzepatide are typically dispensed in vials — either pre-mixed liquid with the mg/mL on the label, or a dry powder you reconstitute yourself — and drawn up with a U-100 insulin syringe. That workflow has no dose dial, so converting milligrams to syringe units falls to you and your pharmacist. The guides to tracking semaglutide and tracking tirzepatide cover how units fit into the weekly log alongside milligrams.
What decides it is the form, not the brand. A pen meters the volume itself — you dial or click the labeled dose and the device delivers it — so a pen workflow has nothing to convert, whether the pen is a single-dose Wegovy or Ozempic pen, a multi-dose FlexTouch, or a KwikPen. The prefilled single-dose syringes on the semaglutide labels come filled to their dose too, which is a different object from an empty U-100 syringe and a vial. A vial has no dose dial, which is why the tirzepatide labels tell patients using vials to use a syringe capable of measuring the dose and a new syringe and needle for every injection. Mounjaro and Zepbound are each supplied as single-dose vials in all six strengths and as multi-dose vials holding four doses, next to their pens — Zepbound's vials are one example of that split, and being on a brand-name product says nothing on its own about whether syringe math is part of your week.
One difference still separates the two kinds of vial. A branded vial's label names the volume for each dose — 0.5 mL from a single-dose vial, 0.6 mL from a multi-dose one, which on a U-100 scale is 50 and 60 units — so there is a stated number to draw to. A compounded vial hands you a concentration instead and leaves the volume to be worked out, and that is the case this calculator is built for.
This page converts a prescribed dose into syringe marks, and that's all it does. Which dose belongs to which week is a titration question — the titration schedule planner turns the label ladders into calendar dates — and what results to expect is what the weight loss calculator estimates from trial data. Once the dose is drawn, the recurring problem is remembering the next one: that's the job of the GLP-1 shot tracker app.
Frequently asked questions
How many units is 2.5 mg of tirzepatide?
It depends entirely on the concentration in your vial. The formula is units = mg ÷ (mg/mL) × 100. At 10 mg/mL, 2.5 mg is 25 units on a U-100 syringe; at 17 mg/mL it is about 14.7 units. There is no fixed answer without the mg/mL figure.
Why do two people on the same dose draw different unit amounts?
Because units measure volume, not milligrams. A 5 mg dose at 10 mg/mL is 50 units, while the same 5 mg at 20 mg/mL is 25 units — half the volume for an identical dose. The concentration printed on your vial is what makes the numbers differ.
What does U-100 mean on an insulin syringe?
U-100 means the syringe scale assumes 100 units per milliliter, so one unit is 0.01 mL and a full 1 mL syringe holds 100 units. That is why units equal mL × 100 for any liquid drawn into it — the marks measure volume, regardless of what the liquid is.
When should you not rely on a units calculator?
A units calculator is the wrong tool whenever a pen delivers your dose, because pens meter the volume themselves, and whenever a branded vial’s label already names the volume for each dose. Call your pharmacist if the concentration is unlabeled or unclear, or if the result disagrees with your instructions: the math only reflects the mg/mL entered.
KeepAlong is an independent app and website. Not affiliated with, endorsed by, or sponsored by Novo Nordisk or Eli Lilly.