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Reconstitution · Tirzepatide

Tirzepatide dosage & reconstitution calculator

Pick the vial, the water you added and the dose. Get the exact draw in units for the syringe in your hand.

Step 1 of 4

  1. How many mg are in your vial?
    Vial amounttotal mg in the calculation
  2. How many mL of water did you add?
  3. What dose do you want to convert?
  4. Which syringe are you using?
Draw to
50.0units

0.50 mL in the syringe · 4 calculated doses from this amount

50.0 units on a U-100 insulin syringe · 1 mL · lines every 2 units, which is 0.50 milliliters. The draw lands on a syringe line.

Easy to read on this syringe. The calculated volume matches the 50-unit line. No rounding is needed.

10 mg ÷ 2 mL = 5.00 mg/mL
→ 50 mcg/unit · 2.5 mg = 0.500 mL = 50.0 units

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Show the math and syringe details

Can this syringe show the result clearly?

Easy to read on this syringe. 50.0 u is exactly the 50-unit line on a U-100 — no rounding error at all.

Want an easier syringe number?

This setup is already easy to read. Changing the water between 0.5 and 3 mL would not put 2.5 mg closer to a line on this U-100 syringe.

Adding more water makes the mixture less concentrated, so the same dose uses more syringe units. It does not change how much peptide is in the vial.

This setup is in the address bar — every input is part of the link.

Educational math, not medical advice — dosing decisions belong to a licensed clinician. The available tabs also show supply calculations and any sourced schedule.

How to use the calculator

  1. 1

    Enter the amount in the vial

    Use the total mg printed on your Tirzepatide vial.

  2. 2

    Enter the water you added

    Use the amount of water added to that vial, in mL.

  3. 3

    Enter the dose you want to convert

    Choose mg or mcg, then match the result to your syringe.

Tirzepatide is the drug in Zepbound and Mounjaro. It works on two gut hormone signals involved in appetite and blood sugar. People take Zepbound for long-term weight management and Mounjaro for type 2 diabetes.

Both products have FDA approval and use weekly injections. Their labels cover different uses, so the product name matters.

Examples using 10 mg of Tirzepatide

Each row uses 10 mg and the liquid volume shown. Dividing the amount by that volume gives the calculated concentration. The rows are arithmetic examples, not alternative product preparations.

◆ How liquid volume changes the resultdose used: 2.5 mg

With 1 mL bacteriostatic water

25.0 units

Concentration
10.00 mg/mL
Each U-100 unit
100.0 mcg
Syringe volume
0.250 mL
Nearest line
26 units · 4.0% off

With 2 mL bacteriostatic water

50.0 units

Starting example
Concentration
5.00 mg/mL
Each U-100 unit
50.0 mcg
Syringe volume
0.500 mL
Nearest line
Exactly 50 units

With 3 mL bacteriostatic water

75.0 units

Concentration
3.33 mg/mL
Each U-100 unit
33.3 mcg
Syringe volume
0.750 mL
Nearest line
76 units · 1.3% off

The amount, liquid volume and dose shown here are the calculator’s starting example for Tirzepatide. Replace them with your own values. Every result in the table is calculated from those inputs.

Drawn from once a week at 2.5 mg, a 10 mg vial yields 4 doses — about 4.0 weeks of supply. No storage limit is assigned to this example. Follow the dispensing label for the specific product.

Tirzepatide: the same dose can take a different draw

The tirzepatide examples span several vial amounts. A dose entered in milligrams can occupy a small part of the syringe or more than its capacity, depending on the concentration. The unit count belongs to the setup shown.

Open the mixing details3 notes

Identify what the container measures

A pen dose setting, the concentration of a ready-made liquid and the total amount in a powder vial describe different things. This calculator models the amount in a vial and the liquid volume entered. It does not identify a product from the name tirzepatide.

A powder vial is not proof of pharmacy compounding or of an approved product. Its appearance cannot establish its contents or strength. The calculator needs those details as inputs; it cannot verify them or replace the instructions supplied with a medicine.

A changed dose needs a new calculation

If the entered dose increases while the vial amount and water stay fixed, the required volume increases too. Keeping the old unit count would keep the old amount. The calculator recomputes the draw from the updated dose rather than adjusting a previous answer by eye.

That relationship does not decide when a dose should change. A dose schedule includes timing and product instructions that the conversion alone cannot supply. An unchanged dose still needs a new calculation if the concentration changes between vials.

Read a small draw with its measurement details

More tirzepatide in the same liquid volume produces a higher concentration. For a fixed dose, that means a smaller draw. A small difference in syringe units can then represent a larger share of the intended amount.

The result shows the calculated volume alongside the syringe scale. When it falls between lines, the measurement details explain that gap. Changing the water input changes the volume shown; it does not add medicine to the vial or establish how the vial should be prepared.

Tirzepatide: the starting dose is not the maintenance dose

The Zepbound label separates the starting dose from the doses used for ongoing treatment. This calculator converts an amount into a draw; it cannot choose a step in that schedule.

Read the supporting evidence3 supporting notes

Dose changes also depend on time

The label spaces increases at least four weeks apart and considers how treatment is working and how well it is tolerated. A syringe calculation does not track either of those things, or the date of the last injection.

A powder vial is different from Zepbound

Zepbound comes as a ready-made solution. Its pen or vial instructions do not describe mixing a powder. The strength on the actual container and any dispensing instructions are needed to interpret a different preparation.

Vial supply does not establish a storage date

The number of draws left is a calculation, not proof that a mixed vial will keep for that long. A general opened-vial limit does not replace the date and storage instructions supplied for a particular product.

Units to dose at 5.00 mg/mL

Mix 10 mg into 2 mL and one U-100 unit carries 50.0 mcg. The table shows how much peptide is in each numbered syringe line. These are conversion examples, not suggested doses.

Open the unit conversion table10 rows
Numbered U-100 syringe lines converted to volume and mass at 5.00 milligrams per milliliter.
U-100 lineVolumeMass (mcg)Mass (mg)
10 u0.10 mL500 mcg0.5 mg
20 u0.20 mL1,000 mcg1 mg
30 u0.30 mL1,500 mcg1.5 mg
40 u0.40 mL2,000 mcg2 mg
50 u0.50 mL2,500 mcg2.5 mg
60 u0.60 mL3,000 mcg3 mg
70 u0.70 mL3,500 mcg3.5 mg
80 u0.80 mL4,000 mcg4 mg
90 u0.90 mL4,500 mcg4.5 mg
100 u1.00 mL5,000 mcg5 mg

Where repeated Tirzepatide doses settle

Each weekly dose lands before the last one has cleared. So the level in the body climbs for a while, then holds steady. The half-life here is 5 days, which leaves 38% of a dose still there a week later. The level settles at about 1.61× what one dose gives. It gets 95% of the way there after 4 doses, roughly 3 weeks in.

Open the weekly build-up table9 rows
For each dose: the estimated level just after it and just before the next dose, compared with the first dose, plus how close the peak is to the long-term level.
DoseLevel afterLevel before the nextShare of long-term level
11.00×0.38×62%
21.38×0.52×86%
31.52×0.58×95%
41.58×0.60×98%
51.60×0.61×99%
61.61×0.61×100%
71.61×0.61×100%
81.61×0.61×100%
Plateau1.61×0.61×100%

Half-life Zepbound (tirzepatide) prescribing information — DailyMed (NIH) · retrieved 2026-09-19. Every other figure is arithmetic on that half-life and the interval.

These are ratios, not blood levels. Turning them into an actual concentration would need more information than the cited source provides. The simple model is also only an approximation of how a drug really behaves in a body. The Accumulation tab plots the same math at whatever interval you pick.

How the math works

  1. Concentration — divide the amount entered by the liquid volume used in the calculation: mg ÷ mL = mg/mL. This tells you how many mg are in each mL.
  2. Volume — the dose divided by that concentration: dose ÷ (mg/mL) = mL.
  3. Units — on a U-100 syringe one unit is 0.01 mL, so mL × 100 = units. A U-40 unit is 0.025 mL, so the wrong barrel is a 2.5× error. That is why the calculator asks which one you have.
  4. Rounding gap — the exact draw against the nearest syringe line: |exact − nearest line| ÷ exact × 100 = % difference.

Medically reviewed by Kenneth Montecillo, MD2026-09-07open the primary sources

Useful guides for this calculation

The math is only one part of the question. These guides cover the compound, published doses, side effects, mixing steps and supplies.

Whether tirzepatide may still be compounded

The tirzepatide shortage was resolved on 2024-12-19, and every date after that turns on it.

The tirzepatide titration schedule, step by step

All 6 steps from the tirzepatide label, with a source beside every row.

Which tirzepatide reactions warrant medical attention

Including the tirzepatide boxed warning, quoted from the document that carries it.

How tirzepatide differs from the rest of its class

The FDA label gives a 6-step dosing schedule for tirzepatide.

Tirzepatide injection sites, timing and rotation

What the tirzepatide Instructions for Use specify, quoted rather than paraphrased.

The tirzepatide ladder in syringe units

All 6 rungs of the tirzepatide ladder, converted at one mix rather than described in general.

Questions readers ask

How do you calculate reconstitution?

Start with the concentration. Divide the vial strength by the water added to get mg/mL. Five vial sizes and three water amounts make fifteen possible concentrations.

Then units are dose divided by concentration, times 100. The 2.5 mg starting quantity is 4.2 units from a 60 mg vial in 1 mL. From a 5 mg vial in 3 mL it is 150 units, which does not fit a barrel.

How do I reconstitute 20 mg of tirzepatide?

For a 20 mg vial, 1 mL gives 20 mg/mL, 2 mL gives 10 mg/mL and 3 mL gives 6.67 mg/mL.

The 2.5 mg starting quantity then reads 12.5, 25 or 37.5 units. A 20 mg vial holds eight of those, and fewer as the schedule climbs. That climb is the trap here: same vial, same water, new dose, new unit count.

How much water to reconstitute 10 mg of tirzepatide?

With a 10 mg vial, adding 1, 2 or 3 mL produces concentrations of 10, 5 or 3.33 mg/mL. A 2.5 mg amount then draws 25, 50 or 75 units.

The whole span stays on one barrel, which is not true of the 5 mg vial at 3 mL. A 10 mg vial holds four starting doses. At the 15 mg maintenance quantity it does not hold one.

How to mix tirzepatide calculator?

Enter three things and the tool returns the fourth: vial strength, water volume and dose give the units. It also counts the doses in the vial and flags a draw too long for the barrel.

It cannot pick the dose. The labeled steps run 2.5 mg, then 5, 7.5, 10, 12.5 and 15 mg, no faster than four weeks apart. Those choices belong to a prescriber, and each step changes the unit count.

1primary source, each with the day we read it — open the documents used on this page