Tirzepatide Dosage CalculatorTirzepatide Units Calculator & Titration Planner
Turn your prescribed tirzepatide dose in mg into the exact insulin-syringe units for a compounded multi-dose vial. Then map the FDA-labelled 2.5 mg step-up schedule onto your own vial, see how many vials each step uses, and check what to do after a missed dose.
- ✔ mg → units for U-100, U-40 & mL syringes
- ✔ Titration schedule from the Zepbound label
- ✔ Missed-dose checker
- ✔ Vial & beyond-use-date planner
Tirzepatide is an FDA-approved prescription medicine — Mounjaro® for type 2 diabetes and Zepbound® for chronic weight management and obstructive sleep apnea. Brand pens deliver a fixed dose and need no unit math. This calculator is for compounded multi-dose vials drawn with a syringe. It converts the dose your prescriber set; it doesn’t choose one. Always follow your prescription and pharmacy label.
Tirzepatide Units Calculator
Enter what your pharmacy label says, pick your prescribed dose and syringe. Results, alerts and the titration plan update as you type.
= 0.250 mL of a 10 mg/mL solution for a 2.5 mg dose · lands on a printed mark
Titration planner
FDA-labelled 2.5 mg steps on your vial| Step | Dates | Weekly dose | Draw | mg in step |
|---|
The label allows a dose increase only after at least 4 weeks on the current dose, and 2.5 mg is a starting dose, not a maintenance dose. Your prescriber may keep you on a step longer or stop below 15 mg. The vial count assumes each vial is discarded at its beyond-use date and that partial doses aren’t combined from two vials.
Missed-dose checker
based on the FDA label ruleYour vial label
How Many Units Is 2.5 mg of Tirzepatide?
At 10 mg/mL, 2.5 mg of tirzepatide is 25 units on a U-100 insulin syringe (0.25 mL). At 20 mg/mL (for example, 40 mg in 2 mL) it is 12.5 units, and at 5 mg/mL it is 50 units. Brand-name Mounjaro and Zepbound pens deliver a fixed dose, so you don’t measure units at all.
The concentration on your compounded vial label decides everything. Divide the dose in mg by the mg/mL to get millilitres, then multiply by 100 for U-100 units. Because compounding pharmacies use different strengths, a “units” number from a friend, a forum or a previous vial can be wrong for your vial — by a factor of two or more. That is exactly the kind of error the FDA has warned about with compounded GLP-1 injections.
Tirzepatide Dosage Chart in Units (U-100)
Units to draw for each FDA-labelled dose step at common compounded concentrations. Find your label’s mg/mL in the first column.
| Concentration | 2.5 mg | 5 mg | 7.5 mg | 10 mg | 12.5 mg | 15 mg |
|---|---|---|---|---|---|---|
| 5 mg/mL | 50 u | 100 u | 150 u · 2 draws | 200 u · 2 draws | 250 u · 2 draws | 300 u · 2 draws |
| 10 mg/mL | 25 u | 50 u | 75 u | 100 u | 125 u · 2 draws | 150 u · 2 draws |
| 12.5 mg/mL | 20 u | 40 u | 60 u | 80 u | 100 u | 120 u · 2 draws |
| 15 mg/mL | 16.67 u | 33.33 u | 50 u | 66.67 u | 83.33 u | 100 u |
| 20 mg/mL | 12.5 u | 25 u | 37.5 u | 50 u | 62.5 u | 75 u |
| 25 mg/mL | 10 u | 20 u | 30 u | 40 u | 50 u | 60 u |
| 30 mg/mL | 8.33 u | 16.67 u | 25 u | 33.33 u | 41.67 u | 50 u |
“u” = units on a U-100 insulin syringe (100 units = 1 mL). Values above 100 units need more than one draw — ask your pharmacy whether a stronger concentration is appropriate.
Which Tirzepatide Products Need a Units Calculation?
| Product | How the dose is set | Need this calculator? |
|---|---|---|
| Mounjaro® single-dose pen | Fixed dose per pen (2.5–15 mg) | No |
| Zepbound® single-dose pen | Fixed dose per pen (2.5–15 mg) | No |
| Zepbound® single-dose vial | Each vial holds one dose in 0.5 mL; the instructions say to draw the full contents | No — draw the whole vial |
| Zepbound® KwikPen (approved Feb 2026) | Multi-dose pen delivering four fixed doses | No |
| Compounded multi-dose vial | You draw a volume with a syringe, so the strength on the label matters | Yes |
How to Convert Tirzepatide mg to Units
Concentration (mg/mL) = label value, or vial mg ÷ mL of liquid
Volume (mL) = dose mg ÷ concentration
Units = volume × 100 (U-100) or × 40 (U-40)
Weekly doses per vial = vial mg ÷ dose mg (round down)
Worked example (the calculator’s default)
- Label: 10 mg/mL, 1 mL vial → 10 mg total
- 2.5 mg ÷ 10 = 0.25 mL → × 100 = 25 units
- 10 ÷ 2.5 = 4 weekly doses, the 4-week starting month, used inside a 28-day beyond-use date
Same dose, different vial
A 5 mg dose is 50 units at 10 mg/mL but 25 units at 20 mg/mL. If your pharmacy changes the concentration between refills, your units change too — even though your dose hasn’t. Re-check the label every time you get a new vial.
Pharmacist’s note: the most dangerous mix-up
The FDA has received reports of patients overdosing on compounded GLP-1 injections, often because they confused units with mg or mL, or used a syringe that didn’t match their instructions. Some patients drew 5–20 times their intended dose. Read the dose in mg on your prescription, the mg/mL on the vial, and the units on the syringe — and if any of the three doesn’t match what you expected, stop and call the pharmacy.
Tirzepatide Dosing Schedule (FDA-Labelled Titration)
Mounjaro and Zepbound use the same six dose strengths and the same step-up rule. According to the FDA prescribing information, treatment starts at 2.5 mg once weekly for 4 weeks. The dose then increases in 2.5 mg steps, with at least 4 weeks on each dose, up to a maximum of 15 mg once weekly.
| Step | Weekly dose | Minimum time | Label role |
|---|---|---|---|
| 1 | 2.5 mg | 4 weeks | Starting dose only — to improve tolerability, not a treatment dose |
| 2 | 5 mg | 4 weeks | Maintenance option (Zepbound weight management; Mounjaro) |
| 3 | 7.5 mg | 4 weeks | Escalation step |
| 4 | 10 mg | 4 weeks | Maintenance option, including Zepbound for sleep apnea |
| 5 | 12.5 mg | 4 weeks | Escalation step |
| 6 | 15 mg | — | Maximum labelled dose |
Summarized from the Zepbound and Mounjaro prescribing information. Zepbound lists 5, 10 and 15 mg as maintenance doses for weight management, and 10 or 15 mg for obstructive sleep apnea. Your prescriber may move more slowly if side effects are a problem.
Missed a dose? The label rule
- 4 days (96 hours) or less late: take the missed dose as soon as possible, then resume your usual day.
- More than 4 days late: skip it and take the next dose on your regular day.
- Doses must be at least 3 days (72 hours) apart.
- Missed two or more doses in a row? Ask your prescriber before restarting — they may lower the dose.
Changing your injection day
You can move your weekly injection day, as long as the last dose was at least 3 days (72 hours) earlier. Once you’ve switched, keep the new day.
What the Tirzepatide Trials Showed
Tirzepatide is a once-weekly dual GIP and GLP-1 receptor agonist — a 39-amino-acid peptide with a half-life of about 5 days. Unlike most peptides on this site, it has large randomized trials behind it. These are averages from the trials, not predictions for any one person.
| Trial | Who | Key result |
|---|---|---|
| SURMOUNT-1 (NEJM 2022) | 2,539 adults with obesity or overweight, without diabetes; 72 weeks | Average weight change −15.0% (5 mg), −19.5% (10 mg) and −20.9% (15 mg) vs −3.1% on placebo |
| SURMOUNT-5 (NEJM 2025) | 751 adults with obesity; tirzepatide vs semaglutide, 72 weeks | −20.2% with tirzepatide vs −13.7% with semaglutide |
| SURPASS-2 (NEJM 2021) | 1,879 adults with type 2 diabetes; vs semaglutide 1 mg, 40 weeks | Greater HbA1c reduction at every dose; weight −7.6 to −11.2 kg vs −5.7 kg |
| SURMOUNT-OSA (NEJM 2024) | Adults with obesity and moderate-to-severe sleep apnea | Large reductions in breathing interruptions; basis for the Dec 2024 sleep-apnea approval |
Weight figures are treatment-regimen estimates reported in each trial. Results in the trials came alongside diet and activity counselling.
Is Compounded Tirzepatide Legal in 2026?
Brand-name tirzepatide is fully approved. Compounded tirzepatide was widely available during the 2022–2024 shortage, but the rules have tightened sharply since the shortage ended.
- December 2022
Tirzepatide is added to the FDA drug shortage list, allowing pharmacies to compound copies.
- December 19, 2024
After re-evaluating, the FDA confirms the shortage is resolved.
- February 18 & March 19, 2025
FDA enforcement discretion ends for 503A pharmacies (February 18) and 503B outsourcing facilities (March 19). A federal court later backs the FDA’s decision.
- April 30, 2026
FDA proposes excluding tirzepatide, semaglutide and liraglutide from the 503B bulks list, finding no clinical need for outsourcing facilities to compound them from bulk substance.
- As of October 17, 2026
A 503A pharmacy may compound tirzepatide only for an individual patient with a documented need for a change from the approved product, not as a routine copy. If you use a compounded vial, it should come from a state-licensed pharmacy with a prescription in your name.
Tirzepatide Safety, Side Effects and Storage
Key safety points from the label
- Boxed warning: thyroid C-cell tumors in rodents. Don’t use with a personal or family history of medullary thyroid carcinoma or MEN 2.
- Most common side effects: nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion and injection-site reactions — usually worst after a dose increase.
- Other warnings include pancreatitis, gallbladder problems, kidney injury from dehydration, and low blood sugar when used with insulin or a sulfonylurea.
- Tell your anesthetist before surgery: GLP-1 medicines slow stomach emptying and can raise aspiration risk.
A pharmacist’s two most-missed points
- Birth control pills: tirzepatide can make oral contraceptives less effective. The label advises switching to a non-oral method, or adding a barrier method, for 4 weeks after starting and after each dose increase.
- Protein and muscle: rapid weight loss includes some lean mass. Ask about a protein target and resistance exercise — the protein requirement calculator is a useful starting point.
Storing brand pens and vials
Refrigerate at 2–8 °C (36–46 °F) and don’t freeze. If needed, they can be kept unrefrigerated at up to 30 °C (86 °F) for up to 21 days. Protect from light.
Storing compounded vials
Follow your pharmacy’s label. Compounded vials have a beyond-use date set by the pharmacy, which may be shorter than you expect. The calculator’s discard-by date uses the number of days you enter.
Questions to Ask Your Prescriber or Pharmacist
- What is my dose in mg, and what concentration in mg/mL is this vial?
- How many units should I see on my syringe — and which syringe should I use?
- When should I move to the next dose, and what if side effects are too strong?
- What’s the beyond-use date, and how should I store this vial?
- Do I need to change my contraception or my diabetes medicines?
- Would a brand-name pen or vial be an option for me?
Related Calculators
This tirzepatide tool is part of DexoCalc’s peptide and weight-management cluster. Use the universal calculator for any other vial, or the tools below for the next step in planning.
ALLPeptide Calculator — Reconstitution & Dosage
The universal tool for any peptide, vial or syringe, including powders, blends and 3 mL syringes.
Semaglutide Reconstitution Calculator
The other weekly GLP-1. Its doses start at 0.25 mg, so units are much smaller.
Open calculator → InvestigationalRetatrutide Dosage Calculator
Lilly’s triple-agonist successor to tirzepatide, still in clinical trials.
Open calculator → EligibilityBMI Calculator
Zepbound is labelled for a BMI of 30+, or 27+ with a weight-related condition. Check where you stand.
Open calculator → Lean massProtein Requirement Calculator
Set a daily protein target to help protect muscle while appetite is low.
Open calculator → EnergyTDEE Calculator
Estimate daily calorie needs as your weight changes on treatment.
Open calculator → Metabolic healthDiabetes Risk Calculator
Mounjaro is the type 2 diabetes brand of tirzepatide. Gauge your own risk.
Open calculator →Tirzepatide Dosage Calculator FAQs
At 10 mg/mL it is 25 units on a U-100 syringe; at 20 mg/mL it is 12.5 units; at 5 mg/mL it is 50 units. Always use the concentration on your own vial label.
At 10 mg/mL, 5 mg is 50 units; at 20 mg/mL it is 25 units; at 25 mg/mL it is 20 units on a U-100 syringe.
At 20 mg/mL, 7.5 mg is 37.5 units and 10 mg is 50 units. At 10 mg/mL they are 75 and 100 units — a full 1 mL syringe for 10 mg.
Divide your dose in mg by the vial’s concentration in mg/mL. For example, 2.5 mg ÷ 10 mg/mL = 0.25 mL, which is 25 units on a U-100 syringe.
The FDA label starts at 2.5 mg once weekly for 4 weeks, then increases in 2.5 mg steps after at least 4 weeks on each dose, up to a maximum of 15 mg weekly. Your prescriber decides when, or whether, to step up.
Per the label, if it’s been 4 days (96 hours) or less, take it as soon as possible. If it’s been more than 4 days, skip it and take the next dose on your usual day. Keep doses at least 3 days apart.
No. Single-dose pens and the Zepbound KwikPen deliver fixed doses, and Zepbound single-dose vials are drawn in full. Units only matter for compounded multi-dose vials.
Only narrowly. Since the shortage ended, a 503A pharmacy may compound it only for an individual patient with a documented clinical need, not as a routine copy. In April 2026 the FDA also proposed excluding tirzepatide from the 503B bulks list.
The dose is the same only if you read the right scale. A 0.25 mL draw reads 25 units on a U-100 syringe but 10 units on a U-40 syringe. Reading one scale on the other gives about 2.5 times too much or too little.
Until the earlier of two points: running out of doses, or the beyond-use date on your pharmacy label. A 10 mg vial at 2.5 mg weekly lasts 4 weeks; a 40 mg vial at 2.5 mg would hold 16 doses but may expire well before you use them.
In the SURMOUNT-5 head-to-head trial, people on tirzepatide lost 20.2% of body weight on average over 72 weeks, compared with 13.7% on semaglutide. Which is right for you depends on your health, tolerance and access.
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Manzoor Ahmad, Pharm-D
Licensed Pharmacist · Founder, DexoCalc
Manzoor is a licensed pharmacist with more than nine years of experience writing about supplements and medication safety, and 13+ years building web tools. He runs a community pharmacy, where checking injectable dose conversions is routine work. He checked this calculator against the Mounjaro and Zepbound prescribing information, verified every chart value with the same formulas, and reviews the compounding section whenever FDA policy changes. He does not sell tirzepatide and has no relationship with any manufacturer or telehealth company.
Sources
- U.S. FDA. Zepbound (tirzepatide) Prescribing Information. See DailyMed for the current version.
- U.S. FDA. Mounjaro (tirzepatide) Prescribing Information — DailyMed.
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022;387:205–216. NEJM.
- Aronne LJ, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med. 2025. NEJM.
- Frías JP, et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med. 2021;385:503–515. NEJM.
- Malhotra A, et al. Tirzepatide for the treatment of obstructive sleep apnea and obesity (SURMOUNT-OSA). N Engl J Med. 2024. NEJM.
- U.S. FDA. FDA’s concerns with unapproved GLP-1 drugs used for weight loss (including dosing-error reports).
- Frier Levitt. FDA determines (again) the tirzepatide shortage is resolved.
- Federal Register. List of Bulk Drug Substances for Which There Is a Clinical Need Under Section 503B, May 1, 2026.
- Drugs.com. Zepbound FDA approval history (vials and KwikPen).
Disclaimer: This tirzepatide calculator is an educational arithmetic tool. It does not prescribe, recommend or change any dose. Use it only to double-check a dose prescribed by a licensed clinician and dispensed by a licensed pharmacy, and confirm every syringe reading with your pharmacist. Mounjaro®, Zepbound® and KwikPen® are trademarks of Eli Lilly and Company; DexoCalc is not affiliated with Eli Lilly or any compounding pharmacy.