Tirzepatide Reconstitution Calculator
Use a target number you already have to calculate concentration, injection volume, and U-100 syringe units. Arithmetic only. This tool never selects a dose for you.
This calculator handles one mechanical step. Once you enter the peptide amount in the vial, the water volume, and a target number from your own protocol source, it calculates the resulting concentration and draw volume. It does not interpret your goals, choose a target, or turn the result into a protocol.
Enter your own numbers
The target dose starts at zero, with no figure suggested for you. Drag the slider to the number from your own protocol source and the results appear below.
Target dose from your protocol source. The slider starts at zero and no dose is suggested. Drag it to the figure your own source specifies and the math updates as you move it.
What the evidence and the community report
These are amounts recorded in published studies and label documents, not recommendations. The Who column says where each figure came from, and the Ref column ties the row to the numbered source list further down this page.
A. Approved label doses
Mounjaro and Zepbound, as published on DailyMed.
| Amount | Schedule | Route | Who | Ref |
|---|---|---|---|---|
| 2.5 mg to start, increased to 5 mg, then 2.5 mg increments | once weekly, 5 mg after 4 weeks, later steps after at least 4 weeks | subcutaneous | human, adults with type 2 diabetes | [7] |
| maximum 15 mg in adults, maximum 10 mg in pediatric patients | once weekly | subcutaneous | human, adults and pediatric | [7] |
| 2.5 mg to start, then 2.5 mg increments | once weekly for 4 weeks, then steps after at least 4 weeks | subcutaneous | human, all Zepbound indications | [8] |
| 5 mg, 10 mg or 15 mg | once weekly | subcutaneous | human, weight reduction | [8] |
| 10 mg or 15 mg | once weekly | subcutaneous | human, sleep apnea | [8] |
| maximum 15 mg, all indications | once weekly | subcutaneous | human | [8] |
B. Amounts administered in published studies
Given under trial conditions, with monitoring.
| Amount | Schedule | Route | Who | Ref |
|---|---|---|---|---|
| 10 mg or 15 mg | once weekly for 72 weeks | subcutaneous | human, n not stated | [9] |
| 5 mg, 10 mg or 15 mg | once weekly | subcutaneous | human, n not stated | [10] |
| 5 mg or 10 mg | once weekly, 30 weeks double blind then 22 week open label | subcutaneous pen | human, ages 10 to under 18, n not stated | [11] |
| 5 mg, 10 mg or 15 mg | once weekly for 72 weeks, 20 week escalation | subcutaneous | human, n=2,539 | [1] |
C. Community reported practice
Self-reported, not peer reviewed, published by a source that profits from supply.
Disclaimer: no figure in these tables is a recommendation, and what to take, if anything at all, is a decision for a licensed prescriber who knows your history.
Two worked math illustrations
Both examples use 250 mcg because it is a round number that keeps the arithmetic easy to follow. It is not a recommendation and not a dose to take. Use the figure your own protocol source specifies.
Example A: 5 mg vial with 2 mL
Math illustration, not a dose to take. The concentration is 5 / 2 = 2.5 mg/mL, or 2500 mcg/mL. A 250 mcg target gives 250 / 2500 = 0.1 mL, which is 10 units on a U-100 syringe. The vial contains 5000 / 250 = 20 illustrative draws.
Example B: 10 mg vial with 3 mL
Math illustration, not a dose to take. The concentration is 10 / 3 = 3.33 mg/mL, or about 3333 mcg/mL. A 250 mcg target gives 0.075 mL, which is 7.5 units on a U-100 syringe. The vial contains 10000 / 250 = 40 illustrative draws.
The target number stays the same in both illustrations, while the vial amount and water volume change the concentration and syringe reading. Enter your own numbers above to run the same calculation.
What this calculator calculates, and what it leaves to you
A reconstitution calculator answers a mechanical question. You have a vial containing a stated amount of peptide and add a known volume of water. That fixes the concentration. From there, any target number you enter has one matching liquid volume, and the calculator finds it. There is no judgment in that step, only division.
The calculator does not choose the target number. It does not read your weight or goals and hand back an instruction. The dose is something you bring to the tool from a licensed prescriber or a protocol source you trust. If you do not have that number, no calculation on this page can supply one.
Reconstituting a tirzepatide vial
If your vial contains lyophilized powder, reconstitution means adding the water volume you entered above and letting the powder dissolve. These are general vial-handling steps, not instructions for choosing or administering a dose.
- Wipe both rubber stoppers, the peptide vial and the water vial, with an alcohol swab and let them dry.
- Draw the water volume you entered in the calculator into a syringe.
- Insert the needle at a slight angle so the water runs down the inside wall of the vial rather than directly onto the powder.
- Inject the water slowly. Do not shake the vial. Swirl gently until the solution is clear.
- Label the vial with the date and the calculated concentration in mg/mL.
- Follow the supplier's written storage and handling instructions.
Water choice and storage sit outside the calculator's arithmetic. For the difference between the two common water types, see bacteriostatic water vs sterile water. For a general mixing walkthrough, see how to use peptides.
How water volume changes the calculation
The amount of water entered does not change how much peptide is in the vial. It changes the concentration and therefore the liquid volume for the target number you enter. A 10 mg vial reconstituted with 1 mL is twice as concentrated as the same vial with 2 mL, so the draw is half the volume for the same target. More water spreads the syringe marks out, while less water concentrates the draw. The calculator recomputes instantly so you can compare the arithmetic and follow the written instructions that came with your vial.
Reading the calculated syringe units
The calculator uses the U-100 conversion:
1 unit = 0.01 mL
100 units = 1 mL = full 1 mL barrel
A result of 0.5 mL is 50 units, and a result of 0.25 mL is 25 units. The calculator shows both formats so you can match the volume to a U-100 syringe. It also checks the result against the selected 0.3 mL, 0.5 mL, or 1.0 mL barrel capacity.
Why published research does not choose the input
The papers below concern tirzepatide research in defined study settings. This calculator does not turn those publications into an individual target number. It accepts the number you supply and handles only concentration, liquid volume, syringe units, and the number of equal draws in the vial.
The sources are included to mark that boundary, not to turn this page into a compound explainer. For information about the compound itself, read the tirzepatide compound profile.
Sources
1. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022 Jul 21;387(3):205-216. PMID: 35658024. DOI: 10.1056/NEJMoa2206038.
2. Frías JP, Davies MJ, Rosenstock J, Pérez Manghi FC, Fernández Landó L, Bergman BK, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021 Aug 5;385(6):503-515. PMID: 34170647. DOI: 10.1056/NEJMoa2107519.
3. Rosenstock J, Wysham C, Frías JP, Kaneko S, Lee CJ, Fernández Landó L, et al. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1): a double-blind, randomised, phase 3 trial. Lancet. 2021 Jul 10;398(10295):143-155. PMID: 34186022. DOI: 10.1016/S0140-6736(21)01324-6.
4. Malhotra A, Grunstein RR, Fietze I, Weaver TE, Redline S, Azarbarzin A, et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. N Engl J Med. 2024 Oct 3;391(13):1193-1205. PMID: 38912654. DOI: 10.1056/NEJMoa2404881.
5. Nicholls SJ, Pavo I, Bhatt DL, Buse JB, Del Prato S, Kahn SE, et al. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes. N Engl J Med. 2025 Dec 18;393(24):2409-2420. PMID: 41406444. DOI: 10.1056/NEJMoa2505928.
6. Coskun T, Sloop KW, Loghin C, Alsina-Fernandez J, Urva S, Bokvist KB, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept. Mol Metab. 2018 Dec;18:3-14. PMID: 30473097. DOI: 10.1016/j.molmet.2018.09.009.
7. MOUNJARO (tirzepatide) injection, Eli Lilly and Company. DailyMed SPL, section 2.1 Recommended Dosage. https://dailymed.nlm.nih.gov/dailymed/services/v2/spls/d2d7da5d-ad07-4228-955f-cf7e355c8cc0.xml Label wording: the 2.5 mg dosage is for treatment initiation and is not intended for glycemic control.
8. ZEPBOUND (tirzepatide) injection, Eli Lilly and Company. DailyMed SPL, section 2.1 Recommended Dosage and section 2.2 Recommended Maintenance and Maximum Dosage. https://dailymed.nlm.nih.gov/dailymed/services/v2/spls/487cd7e7-434c-4925-99fa-aa80b1cc776b.xml Label wording: the 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage. The sleep apnea maintenance range starts higher than the weight management range, and the two indications are not interchangeable.
9. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial. Lancet. 2023. PMID: 37385275. Adults with obesity and type 2 diabetes, BMI 27 or higher, randomized 1:1:1, total not stated in the abstract text retrieved.
10. Tirzepatide versus insulin glargine in type 2 diabetes and increased cardiovascular risk (SURPASS-4): a randomised, open-label, parallel-group, multicentre, phase 3 trial. Lancet. 2021. PMID: 34672967. Adults with type 2 diabetes and high cardiovascular risk, randomized 1:1:1:3 against insulin glargine, 187 sites in 14 countries.
11. Efficacy and safety of tirzepatide in children and adolescents with type 2 diabetes (SURPASS-PEDS): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2025. PMID: 40975112. Children and adolescents aged 10 to under 18 with youth-onset type 2 diabetes, randomized 1:1:1, total not stated in the abstract text retrieved.
12. FormBlends, Compound Tirzepatide Dosing Chart, fetched 2026-08-04. https://formblends.com/articles/glp1-hub/compound-tirzepatide-dosing-chart Self-reported and not peer reviewed, a self-selected community rather than a study population. Commercial interest: this publisher runs a referral model connecting patients to compounding pharmacies and telehealth providers.
Frequently asked questions
Does this calculator choose a tirzepatide dose?
No. The target dose slider starts at zero and no result appears until you drag it to a figure yourself, so the page never puts a number in front of you. Whatever figure you set has to come from your own prescriber or a protocol source you trust. The tool calculates concentration and draw volume from that number and nothing else.
How do I enter a different target number?
Move the target dose slider and use the unit selector to work in mcg or mg. The calculator recomputes the injection volume, the insulin syringe units, and how many equal draws the vial contains. It does not judge the number you enter. It only does the arithmetic on it.
How much BAC water do I add to a 10 mg vial?
There is no single answer from the calculator because water volume changes concentration and syringe readability, not the amount of peptide in the vial. A 10 mg vial in 2 mL gives 5 mg/mL. The same vial in 1 mL gives 10 mg/mL, so the same target number draws half the liquid volume at the higher concentration. Use the written instructions from your supplier. For the same arithmetic without a compound preset, use the general peptide reconstitution calculator.
Why does changing BAC water change the syringe reading?
The amount of peptide in the vial stays fixed. Adding more water lowers the concentration, so the same target number needs a larger liquid volume. Adding less water raises the concentration, so the same target number needs a smaller liquid volume. The calculator updates both millilitres and U-100 syringe units when you move the water slider.
Why does the vial warning appear?
The warning appears when the requested dose is larger than the total peptide entered for the vial. No reconstitution volume can produce that result. Check the vial amount and the dose entry before using the calculation.
How do I read the U-100 syringe result?
On a U-100 insulin syringe, 1 unit equals 0.01 mL and 100 units equals 1 mL. The calculator multiplies the injection volume in millilitres by 100 and shows the result as syringe units. Check that result against the markings and capacity of the syringe you selected.
Is this calculator medical advice?
No. It is harm reduction education. It performs reconstitution arithmetic on numbers you supply. It does not diagnose, prescribe, or tell you what dose to take. Dose decisions belong with a licensed prescriber. Always cross-check with your protocol source, supplier instructions, and where possible a qualified clinician.
This is harm reduction education, not medical advice
This calculator is for educational use. It converts a dose you already have into a volume and syringe reading. It does not choose a dose. Peptide protocols vary between individuals and compounds. Always cross-check with your protocol source, supplier instructions, and where possible a qualified clinician.