How do I convert mg to units on a U-100 syringe?

A U-100 insulin syringe is graduated for 100 units = 1 mL. So Units = (Dose mg / Vial concentration mg per mL) × 100. Example: a 5 mg vial reconstituted in 2 mL gives 2.5 mg/mL. A 0.25 mg dose = 0.1 mL = 10 units on the syringe.

What is the standard semaglutide titration schedule?

Standard FDA-approved titration for Wegovy: weeks 1–4 = 0.25 mg/week, weeks 5–8 = 0.5 mg, weeks 9–12 = 1.0 mg, weeks 13–16 = 1.7 mg, week 17+ = 2.4 mg maintenance. Slower escalation (8 weeks per step) reduces nausea. Wegovy HD (7.2 mg) titrates to higher maintenance after 2.4 mg tolerance is established.

What is the tirzepatide titration schedule?

Standard Mounjaro/Zepbound titration: weeks 1–4 = 2.5 mg/week, weeks 5–8 = 5.0 mg, weeks 9–12 = 7.5 mg, weeks 13–16 = 10 mg, weeks 17–20 = 12.5 mg, week 21+ = 15 mg maintenance. Many clinicians stay at the lowest tolerated dose that's still producing weight loss to minimise side effects and cost.

How long does semaglutide last in the body?

Semaglutide has a half-life of ~7 days, so it requires once-weekly dosing. Steady-state plasma levels are reached after about 4–5 weeks (5 half-lives). Tirzepatide has a similar 5-day half-life, also dosed weekly. Missing one dose drops levels meaningfully — take it as soon as remembered if within 5 days of the missed dose, otherwise skip and resume next scheduled day.

Is this calculator safe to use for compounded vials?

It does the maths correctly — but you must verify the actual concentration on YOUR vial label and confirm the calculation with your prescriber or pharmacist before injecting. Compounded GLP-1s carry additional risks of contamination, mis-dosing and counterfeit products. The FDA has issued warnings about compounded semaglutide/tirzepatide. Brand-name Wegovy/Ozempic/Mounjaro/Zepbound pens have built-in dose dials and are safer where available.

💊 Semaglutide & Tirzepatide Dose Calculator

Convert your prescribed mg dose to units on a U-100 insulin syringe for compounded vials. Includes the standard titration schedule for reference.

Medication

Prescribed Dose (mg per week)

Vial Strength (mg per vial)

Reconstitution Volume (mL of BAC water added)

⚠️ NOT MEDICAL ADVICE. This is a maths tool only. Always verify the concentration on your specific vial label and confirm dosing with your prescriber and pharmacist before injecting. The FDA has issued warnings about compounded semaglutide/tirzepatide quality. Brand-name pens with built-in dose dials are safer where available. Never source from unregulated suppliers.

Understanding the U-100 Syringe

A U-100 insulin syringe is graduated such that 100 units = 1 mL. So one "unit" mark on the syringe = 0.01 mL. The maths is straightforward:

Concentration (mg/mL) = vial mg ÷ recon volume mL
Volume per dose (mL) = prescribed mg ÷ concentration
Units on U-100 syringe = volume mL × 100

Worked Example

You have a 5 mg vial of semaglutide, reconstituted with 2 mL of bacteriostatic water. Your prescription says 0.25 mg/week:

Concentration = 5 ÷ 2 = 2.5 mg/mL
Volume per dose = 0.25 ÷ 2.5 = 0.10 mL
Units on U-100 = 0.10 × 100 = 10 units
Doses per vial = 5 ÷ 0.25 = 20 doses

Standard Semaglutide Titration (Wegovy)

FDA-approved escalation, dose increased every 4 weeks:

Weeks 1–4: 0.25 mg/week
Weeks 5–8: 0.50 mg/week
Weeks 9–12: 1.0 mg/week
Weeks 13–16: 1.7 mg/week
Week 17+: 2.4 mg/week maintenance (or 7.2 mg Wegovy HD if escalated further)

Standard Tirzepatide Titration (Mounjaro / Zepbound)

Weeks 1–4: 2.5 mg/week
Weeks 5–8: 5.0 mg/week
Weeks 9–12: 7.5 mg/week
Weeks 13–16: 10 mg/week
Weeks 17–20: 12.5 mg/week
Week 21+: 15 mg/week maintenance

Slower Titration to Reduce Side Effects

If nausea, vomiting or constipation are severe, many clinicians extend each dose level to 6–8 weeks before escalating. Tolerance generally improves with time. Dropping to the previous dose for 2–4 weeks is a valid recovery move — just communicate with your prescriber.

Storage & Handling

Store reconstituted vials refrigerated (2–8°C / 36–46°F)
Use within 28 days of reconstitution (semaglutide); confirm BUD with your compounder
Do not freeze; if frozen, discard
Inspect before each draw — discard if cloudy, discoloured or contains particles

⚠️

Important Note: This calculator does not substitute for professional medical advice. Compounded GLP-1 medications vary widely in concentration and quality. Always verify the actual label of your specific vial, confirm the dose plan with your prescriber, and never escalate doses on your own. The FDA has documented multiple adverse events from compounded GLP-1 products including dosing errors, contamination and counterfeit ingredients.

Related Calculators

GLP-1 Weight Loss Calculator — Project weight loss on Wegovy, Ozempic, Mounjaro or Zepbound from clinical trial averages.
BMI Calculator — Body Mass Index with WHO health context.
Calorie Deficit Calculator — Daily calorie target to reach a goal weight. BMR + TDEE, weeks-to-goal projection and macro split.