DoseRoutine

Semaglutide Reconstitution Calculator

Semaglutide doses are small — 0.25 mg to 2.4 mg weekly — which means concentration errors are easy to make and expensive to fix. Enter your vial size and BAC water volume to get the exact unit draw.

This is a unit converter. It converts an amount you already have into volume and syringe units. It does not tell you what to take, and it is educational only — not medical advice. Confirm every amount with your clinician and your product label.

Common setups

Vial size (mg)

Total compound in the vial.

BAC water added (mL)

Volume of bacteriostatic water you reconstitute with.

Target dose

Per-injection dose you want to draw.

Syringe type

U-100 = 100 units per mL (standard). U-40 = 40 units per mL.

Draw

10.0 units

on a U-100 insulin syringe (0.100 mL)

Concentration

2.50 mg/mL

Per dose

250 mcg

Doses / vial

~20

Semaglutide concentration reference (mg/mL)

What each vial size becomes at common bacteriostatic water volumes.

Vial	+ 1 mL	+ 2 mL	+ 3 mL	+ 5 mL
2 mg	2.00 mg/mL	1.00 mg/mL	0.67 mg/mL	0.40 mg/mL
5 mg	5.00 mg/mL	2.50 mg/mL	1.67 mg/mL	1.00 mg/mL
10 mg	10.00 mg/mL	5.00 mg/mL	3.33 mg/mL	2.00 mg/mL
15 mg	15.00 mg/mL	7.50 mg/mL	5.00 mg/mL	3.00 mg/mL

Semaglutide dosing at a glance

Phase	Dose	Frequency	Notes
Weeks 1–4	0.25 mg	Once weekly	Tolerance-building dose only.
Weeks 5–8	0.5 mg	Once weekly	First therapeutic step.
Weeks 9–16	1.0–1.7 mg	Once weekly	Escalate every 4 weeks as tolerated.
Week 17+	2.4 mg	Once weekly	Maximum weight-management dose (Wegovy).

Reference ranges reported in the literature and in common practice — not a prescription, and not personalised advice.

What trips people up

5 mg + 2 mL gives 2.5 mg/mL, so 0.25 mg = 10 units and 0.5 mg = 20 units on a U-100 syringe.
Semaglutide is light-sensitive. Keep reconstituted vials in the fridge and in the box.
Doses under 10 units are hard to measure accurately — add more BAC water rather than squinting at the barrel.
Semaglutide slows gastric emptying, which can delay absorption of oral medicines taken at the same time.

How the maths works

Concentration (mg/mL) = vial mg ÷ bacteriostatic water mL.
Volume per dose (mL) = dose mg ÷ concentration.
Syringe units = volume × 100 on a U-100 syringe, or × 40 on a U-40 syringe.
Doses per vial = vial mg ÷ dose mg. Water volume never changes this number.

Semaglutide calculator FAQ

How much BAC water for a 5 mg semaglutide vial?

2 mL is the usual choice: 2.5 mg/mL means a 0.25 mg starting dose is 10 units and 0.5 mg is 20 units. Use 1 mL only if you are already on higher doses and want smaller volumes.

How many units is 0.5 mg of semaglutide?

At 2.5 mg/mL (5 mg + 2 mL), 0.5 mg is 0.2 mL = 20 units on a U-100 syringe. At 5 mg/mL it would be 10 units.

Is compounded semaglutide dosed the same as Ozempic?

The milligram amounts follow the same titration ladder, but pens deliver a fixed metered dose while a compounded vial relies entirely on your own measurement. That is exactly why the concentration maths matters.

How many doses in a 5 mg semaglutide vial?

Twenty 0.25 mg doses, ten 0.5 mg doses, or five 1 mg doses. Total mg divided by dose mg — BAC water volume does not change it.

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Educational tool only — not medical advice. Verify every dose with your prescriber and follow sterile technique. See our medical disclaimer.

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