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Dose calculator: mg ↔ units
For vial-and-syringe users: enter your dose and your vial’s total drug and volume — read your syringe units, with the same realistic fill visual and magnifier as the GLPMate app.
The in-app calculator remembers your device and concentration — and logs the exact mg.
GLPMate adapts to your device — this web tool covers vial + syringe. Pens, auto-injectors and tablets are handled in the app.
This dose is about 25% of the vial.
10 mg ÷ 0.5 mL = 20 mg/mL
Matches your medication — the volume is filled in automatically.
Educational arithmetic, not medical advice. Confirm every conversion with your prescriber or pharmacist — especially after a vial or concentration change. On U-100 a draw over 1 mL is shown on a 2 mL syringe; on U-40 the scale runs 0–40 units per mL.
Auto-injectors are one fixed dose
Single-use auto-injectors deliver a preset dose. GLPMate records the device and the exact mg in one tap — nothing to draw.
The formula
First, concentration = vial’s total drug (mg) ÷ its fluid volume (mL) — a 10 mg / 0.5 mL vial is 20 mg/mL. Then units = (dose mg ÷ concentration) × the syringe scale (100 for U-100, 40 for U-40). Example: a 2.5 mg dose from that vial → 0.125 mL → 12.5 units → 10 mg on U-100, and the 4 vial holds such doses (5 with overfill).
Dose-conversion questions
How do I convert mg to units on a U-100 syringe?
First get your concentration: the vial’s total drug (mg) ÷ its fluid volume (mL). Then units = (dose in mg ÷ concentration) × 100. Example: a 10 mg / 0.5 mL vial is 20 mg/mL, so a 2.5 mg dose is 0.125 mL = 12.5 units.
What does U-100 mean?
A U-100 syringe is marked so that 100 units equal exactly 1 mL. That’s why units = mL × 100 — the markings are just a finer way to read volume. A U-40 syringe marks 40 units per mL instead.
Where do I find the vial’s total mg and volume?
On the vial label or the pharmacy paperwork — the total drug (for example “semaglutide 10 mg”) and the fluid volume (for example “0.5 mL”). Concentration is the first divided by the second. If your label already prints mg/mL, enter that number as the total mg with a 1 mL volume.
How many doses are in my vial?
Divide the vial’s total mg by your dose in mg. A 10 mg vial at 2.5 mg per dose gives 4 doses. Compounded vials are usually filled with ~5% overfill, so you often get one extra — toggle it on to count it. In the app, GLPMate counts this down for you as you log each shot.
Does this work for tirzepatide too?
Yes — the math is identical for any injectable measured in mg with a known concentration. Enter your dose, the vial’s total mg and its volume, then read the units.
Why does GLPMate double-check with a fill visual?
Because unit errors are the most common compounding mistake. Seeing “12.5 units ≈ one-eighth of a 1 mL syringe” — with a magnified read of exactly where the plunger lands — catches order-of-magnitude errors before they happen.
Is this medical advice?
No — it’s arithmetic with a safety rail. Always confirm your dose and conversion with your prescriber or pharmacist, especially when anything changes: vial, concentration or dose.
Your dose, remembered.
Log it once in the app — device, concentration and mg travel with every shot. Free.