Enter vial size (5–60 mg), BAC water volume, and weekly dose to get concentration, syringe units to draw, and doses per vial. Includes the 6-tier titration schedule (2.5–15 mg weekly), vial size comparison, and syringe capacity warnings. Verify tirzepatide quality with independent lab test data on Peptigrity.
A 10 mg vial of tirzepatide reconstituted with 2 mL of bacteriostatic water gives a concentration of 5.0 mg/mL, or 50 mcg per unit on a U-100 syringe. For a 2.5 mg weekly dose, draw the syringe to 50.0 units (0.50 mL). At that dose the vial provides about 4 doses.
Defaults (10 mg vial, 2 mL, 2.5 mg) carried over unchanged from this calculator's live defaults (2 September 2026). Arithmetic only, not a recommendation.
Draw the syringe up to
That's one 2.5 mg dose. Add 2 mL of water to your 10 mg vial first.
| Step | Dose | Draw on a U-100 | Doses per vial |
|---|---|---|---|
| Tier 1 (start) | 2.50 mg | 50 units | 4 |
| Tier 2 | 5 mg | 100 units | 2 |
| Tier 3 | 7.50 mg | Exceeds syringe — split the dose or use less water | 1 |
| Tier 4 | 10 mg | Exceeds syringe — split the dose or use less water | 1 |
| Tier 5 | 12.50 mg | Exceeds syringe — split the dose or use less water | — |
| Tier 6 (max) | 15 mg | Exceeds syringe — split the dose or use less water | — |
Tap any row to load that dose into the calculator above.
The tiers below are the escalation steps stated in the US prescribing information — 2.5 mg weekly, rising by 2.5 mg every 4 weeks to a maximum of 15 mg. They are shown here as commonly cited reference points the syringe-unit columns are calculated against, not as a schedule to follow. Peptigrity is not affiliated with or endorsed by any manufacturer.
| Tier | Weekly dose | Weeks | @ 5 mg/mL | @ 10 mg/mL | @ 15 mg/mL |
|---|---|---|---|---|---|
| Tier 1 (start) | 2.5 mg | Weeks 1–4 | 50 u | 25 u | ~17 u |
| Tier 2 | 5 mg | Weeks 5–8 | 100 u | 50 u | ~33 u |
| Tier 3 | 7.5 mg | Weeks 9–12 | Exceeds syringe | 75 u | 50 u |
| Tier 4 | 10 mg | Weeks 13–16 | Exceeds syringe | 100 u | ~67 u |
| Tier 5 | 12.5 mg | Weeks 17–20 | Exceeds syringe | Exceeds syringe | ~83 u |
| Tier 6 (max) | 15 mg | Week 21+ | Exceeds syringe | Exceeds syringe | 100 u |
At 5 mg/mL concentration (10 mg vial + 2 mL BAC water), doses above 5 mg exceed a standard 100-unit syringe's capacity. Users titrating beyond 5 mg must increase the concentration (use less BAC water) or split the dose across 2 draws. The calculator above flags syringe capacity warnings automatically.
Peptigrity does not recommend a dose; these are the amounts on the approved label and the doses studied in SURMOUNT-1 and SURMOUNT-5. SURMOUNT-1 randomised 2,539 participants for 72 weeks and tested 5, 10 and 15 mg, producing −15.0%, −19.5% and −20.9% against −3.1% on placebo, all at P<0.001; SURMOUNT-5 used maximum tolerated doses of 10 or 15 mg. The table below lists each amount with its source and evidence level.
| Route | Amount | Frequency | Duration | Evidence level |
|---|---|---|---|---|
| Subcutaneous | Titration in 2.5 mg increments | Once weekly | Escalation phase | Approved label |
| Subcutaneous | 5 mg | Once weekly | 72 weeks in SURMOUNT-1 | Human RCT, −15.0% |
| Subcutaneous | 10 mg | Once weekly | 72 weeks in SURMOUNT-1 | Human RCT, −19.5% |
| Subcutaneous | 15 mg | Once weekly | 72 weeks in SURMOUNT-1 | Human RCT, −20.9% |
| Subcutaneous | 10 or 15 mg maximum tolerated | Once weekly | 72 weeks in SURMOUNT-5 | Human RCT, −20.2% |
| Research-market vial | Chosen by the buyer | Chosen by the buyer | Chosen by the buyer | None |
The table separates label from trial deliberately: 2.5 mg is the increment the label escalates in, while 5, 10 and 15 mg are the arms a randomised trial actually ran. At least 20% weight loss was reached by 50% of the 10 mg arm and 57% of the 15 mg arm against 3% on placebo. Which rung anyone occupies is a prescriber's decision.
Concentration is peptide mass divided by diluent volume, and it is the number every later step inherits. No approved reconstitution instruction exists for a research-market tirzepatide vial — the only regulator-backed peptide reconstitution instruction in our fact base belongs to tesamorelin — so the diluent volume is a choice you make rather than one a label makes for you, and it cannot be undone. The worked example below shows that division for a 30 mg vial.
| Step | Value |
|---|---|
| Input: vial label | 30 mg |
| Input: diluent added | 3 mL |
| Calculation | 30 mg ÷ 3 mL |
| Result | 10 mg/mL, or 10,000 mcg/mL |
Write that figure on the vial with the date, because every dose drawn afterwards depends on it and nothing about the liquid reveals it later. The reconstitution calculator performs the same division.
At 10 mg/mL the top two rungs of the ladder exceed a 1 mL barrel. At 20 mg/mL — the same 30 mg vial in 1.5 mL — the entire ladder fits on one barrel, which is the useful contrast: tirzepatide's ladder can be served by a single concentration if you choose one deliberately. The table below gives each weekly amount in U-100 units at 20 mg/mL; the 10 mg/mL figures are in the tier table above.
| Weekly amount | @ 20 mg/mL |
|---|---|
| 2.5 mg | 12.5 units |
| 5 mg | 25 units |
| 7.5 mg | 37.5 units |
| 10 mg | 50 units |
| 12.5 mg | 62.5 units |
| 15 mg | 75 units |
The same rung at two concentrations shows the trade-off. The right-hand column has a cost the left does not: half-unit readings on rungs that land on odd multiples. That is a resolution problem rather than an impossibility, and it is decided before mixing.
| Step | @ 10 mg/mL | @ 20 mg/mL |
|---|---|---|
| Input: intended dose | 7.5 mg | 7.5 mg |
| Volume | 7.5 ÷ 10 = 0.75 mL | 7.5 ÷ 20 = 0.375 mL |
| Units | 75 units | 37.5 units |
One point from what benzyl alcohol permits in a reconstituted vial carries over here: no in-use period can be quoted honestly for a research vial, because no label sets one. The storage step above gives approximately 28 days refrigerated; treat that as a convention, not a label instruction. Flagged for editorial resolution, September 2026.
Identity is not the failure mode on this compound; quantity is. The Purity Index records tirzepatide at 99.75% average purity across 930 independent tests (verified August 2026), while fill variance runs +2.6% to +26.7% against label, with vials labelled 10 to 65 mg testing between 10.71 and 68.1 mg. The table below shows what each point in that recorded range delivers for an intended amount on the 2.5 mg ladder.
| Intended rung | At +2.6% | At +10% | At +26.7% | Where +26.7% lands |
|---|---|---|---|---|
| 2.5 mg | 2.57 mg | 2.75 mg | 3.17 mg | Between rungs one and two |
| 5 mg | 5.13 mg | 5.50 mg | 6.34 mg | Between rungs two and three |
| 7.5 mg | 7.70 mg | 8.25 mg | 9.50 mg | Just under the 10 mg rung |
| 10 mg | 10.26 mg | 11.00 mg | 12.67 mg | Past the 12.5 mg rung |
| 12.5 mg | 12.83 mg | 13.75 mg | 15.84 mg | Above the 15 mg top rung |
| 15 mg | 15.39 mg | 16.50 mg | 19.01 mg | Above any dose ever studied |
At the recorded maximum of +26.7%, an intended 10 mg delivers 12.67 mg — past the next rung up — and an intended 15 mg delivers 19.01 mg, which is above the highest dose ever tested in a randomised trial. The bottom of the recorded range, +2.6%, is genuinely trivial. A 99.75% purity figure is a statement about proportion and says nothing about mass; see why 10 mg isn't 10 mg.
The same overage carried through the arithmetic of a 30 mg vial is shown below. Nothing in the right-hand column is visible at the point of injection: the powder looks the same, the solution looks the same, and the barrel reads 100 units either way.
| Step | If the label is right | If the batch assays +26.7% |
|---|---|---|
| Vial label | 30 mg | 30 mg |
| Peptide mass present | 30 mg | 38.01 mg |
| Diluent | 3 mL | 3 mL |
| Concentration | 10 mg/mL | 12.67 mg/mL |
| A 100-unit draw delivers | 10 mg | 12.67 mg |
You can correct for an overage only when you have a number to correct with, and that number comes from quantitative content testing on your batch. A 30 mg vial that assays at 38.01 mg needs 3.8 mL of diluent rather than 3 mL to return to 10 mg/mL, as the worked example below shows. Without a batch assay there is no correction, because the size of the error is unknown and a range of +2.6% to +26.7% is too wide to split.
| Step | Value |
|---|---|
| Input: label | 30 mg |
| Input: assayed content | 38.01 mg |
| Target concentration | 10 mg/mL |
| Calculation | 38.01 mg ÷ 10 mg/mL |
| Result | 3.8 mL of diluent, not 3 mL |
| A 100-unit draw then delivers | 10 mg, as intended |
It only works before the diluent goes in, because the volume is irreversible once added and topping up an open vial invalidates every dose calculated from it. And it requires an assay of the batch in your hand, not a certificate for a different lot and not a purity percentage. The reverse dose calculator will tell you what a draw delivered on your assumed concentration, which catches transcription errors but not this one.
Injection technique errors, from reusing a transfer needle to injecting into a reactive site, are covered in how to inject peptides.
| Vial size | @ 2.5 mg/wk | @ 5 mg/wk | @ 10 mg/wk | @ 15 mg/wk | Best for |
|---|---|---|---|---|---|
| 5 mg | 2 weeks | 1 week | — | — | Trial / starting dose |
| 10 mg | 4 weeks | 2 weeks | 1 week | — | Tiers 1–2 |
| 15 mg | 6 weeks | 3 weeks | 1.5 weeks | 1 week | Single-tier coverage |
| 30 mg | 12 weeks | 6 weeks | 3 weeks | 2 weeks | Multi-week protocols |
| 60 mg | 24 weeks | 12 weeks | 6 weeks | 4 weeks | Extended protocols |
Shelf life constraint: Reconstituted tirzepatide lasts approximately 28 days. Larger vials may outlast the stability window. Reconstitute only what you need for 4 weeks. For price comparisons, use the cost-per-dose calculator.
| Factor | Tirzepatide | Semaglutide |
|---|---|---|
| Receptor targets | Dual: GIP + GLP-1 | GLP-1 only |
| Starting dose | 2.5 mg weekly | 0.25 mg weekly |
| Maintenance range | 5–15 mg weekly | 1.0–2.4 mg weekly |
| Maximum dose | 15 mg weekly | 2.4 mg weekly (Wegovy) |
| Titration steps | +2.5 mg every 4 weeks | +0.25–0.5 mg every 4 weeks |
| Common vial sizes | 5, 10, 15, 30, 60 mg | 2, 3, 5, 10 mg |
At 5 mg/mL (10 mg vial + 2 mL BAC water), 2.5 mg = 50 units. At 10 mg/mL (10 mg vial + 1 mL BAC water), 2.5 mg = 25 units. At 15 mg/mL, 2.5 mg = approximately 17 units. Use the calculator above with your specific vial and BAC water volume for the exact draw.
1 mL produces 10 mg/mL — suitable for doses up to 10 mg in a single 100-unit draw. 2 mL produces 5 mg/mL — easier to measure small starting doses (2.5 mg = 50 units) but exceeds syringe capacity above 5 mg. Choose based on the tier being calculated.
Reconstituted tirzepatide stored at 2–8°C (standard refrigerator) remains stable for approximately 28 days. Unreconstituted lyophilised powder stored at −20°C maintains integrity for 3–6 months.
Both contain the same 39-amino-acid dual GIP/GLP-1 receptor agonist. Branded tirzepatide is an FDA-approved prescription medicine supplied as a pre-filled pen. Compounded tirzepatide is produced by pharmacies under FDA 503A/503B regulations as lyophilised powder requiring reconstitution — which is what this calculator is for.
Divide the dose (in mg) by the concentration (in mg/mL), then multiply by 100. Example: 5 mg ÷ 10 mg/mL = 0.5 mL × 100 = 50 units. The calculator performs this conversion automatically.
At 2.5 mg/week: 12 doses. At 5 mg/week: 6 doses. At 10 mg/week: 3 doses. At 15 mg/week: 2 doses. However, reconstituted tirzepatide is stable for approximately 28 days — so plan reconstitution in portions if your protocol extends beyond that.
There is no standard volume and no approved reconstitution instruction for a research tirzepatide vial, so the choice is yours. Three millilitres gives 10 mg/mL, which puts 2.5 mg at 25 units but leaves the top two rungs beyond a 1 mL barrel. Half that volume gives 20 mg/mL and fits the whole ladder.