Peptide reconstitution & dose calculator
Pick your peptide, enter the vial size, the bacteriostatic (BAC) water you'll add, and your target dose.
Weekly titration schedule
A common research-context ramp. Units below use your current concentration (5 mg/mL). Slower is gentler on side effects.
| Weeks | Weekly dose | Draw volume | U-100 units |
|---|
How the retatrutide dosage calculator works
Retatrutide is supplied as a lyophilized (freeze-dried) powder that has to be reconstituted with bacteriostatic water before it can be measured and drawn. This calculator turns three simple numbers — your vial size, the amount of BAC water you add, and your target dose — into the two answers you actually need at injection time: the draw volume in mL and the exact units on a U-100 insulin syringe.
The math is straightforward once the powder is dissolved:
- Concentration = vial mg ÷ BAC water mL (e.g. 10 mg ÷ 2 mL = 5 mg/mL)
- Draw volume = target dose mg ÷ concentration mg/mL (e.g. 2 mg ÷ 5 mg/mL = 0.4 mL)
- Units = draw volume mL × 100 (a U-100 syringe holds 100 units per mL, so 0.4 mL = 40 units)
How to reconstitute retatrutide step by step
1. Choose your concentration
The amount of BAC water you add sets the concentration. Less water = more concentrated = fewer units to draw per dose. A 10 mg vial with 2 mL of water gives a clean 5 mg/mL, which many people find easy to measure. There is no single "correct" volume — pick one, then let the calculator show you the resulting units.
2. Add the water slowly
Draw the bacteriostatic water into a syringe and inject it down the inside wall of the vial, not directly onto the powder. Let it dissolve on its own or swirl gently. Do not shake — peptides are fragile and vigorous shaking can degrade them.
3. Store it correctly
Once reconstituted, keep the vial refrigerated (2–8 °C / 36–46 °F). Bacteriostatic water contains a preservative that allows multi-dose use over several weeks.
Reading units on a U-100 syringe
This is where most dosing mistakes happen. A standard insulin syringe is marked U-100, meaning 1 mL is divided into 100 units. You never have to convert milligrams in your head — you just draw to the unit line the calculator gives you. If it says 40 units, pull the plunger to the "40" mark. The syringe diagram above fills to your exact number so there's no guesswork.
Retatrutide dosage chart (10 mg vial at 5 mg/mL)
The reference chart below shows the most common retatrutide setup — a 10 mg vial reconstituted with 2 mL of BAC water for a 5 mg/mL concentration — converted to draw volume and U-100 units at each dose. Your own numbers may differ; the calculator at the top recomputes this instantly for any vial size, water volume, and dose you enter.
| Retatrutide dose | Draw volume | U-100 units |
|---|---|---|
| 1 mg | 0.2 mL | 20 units |
| 2 mg | 0.4 mL | 40 units |
| 3 mg | 0.6 mL | 60 units |
| 4 mg | 0.8 mL | 80 units |
| 6 mg | 1.2 mL | 120 units* |
| 8 mg | 1.6 mL | 160 units* |
| 12 mg | 2.4 mL | 240 units* |
*Doses above 5 mg exceed one U-100 syringe (100 units) at 5 mg/mL. Either split into two draws or reconstitute at a higher concentration (less BAC water) so each dose fits one syringe. The calculator flags this for you.
How much retatrutide should I take?
This calculator answers the mechanical question — how many units is my dose — not the clinical one. In weight-management research, retatrutide is dosed once weekly and titrated upward slowly over months. A frequently referenced ramp starts at 2 mg and steps up every four weeks. The right dose for any individual depends on tolerance, response, and clinical supervision, which is why this tool never prescribes a number: you enter the dose, it returns the exact units. Deciding what dose to take belongs with a qualified clinician.
Retatrutide dosage for weight loss
In weight-management research, retatrutide is titrated upward slowly over several months. Starting low and increasing the dose every few weeks gives the body time to adjust and keeps nausea and GI side effects manageable. The titration table above reflects a commonly referenced ramp (2 mg → 4 mg → 8 mg → 12 mg), recalculated into syringe units for whatever concentration you mixed.
Dosing considerations for women
Dose is driven by individual tolerance and response, not by sex on its own. That said, many people — women included — choose to titrate more gradually, holding each step longer or splitting increases, to stay ahead of nausea. This tool calculates the units for any dose you enter; it does not recommend a dose for you. That decision belongs with a qualified clinician.
Common retatrutide concentrations and which to pick
Because you choose how much bacteriostatic water to add, a single vial size can give several concentrations. The table shows how a 10 mg retatrutide vial behaves at three common water volumes, and what a 2 mg dose looks like at each. More water makes each unit easier to read but means a larger draw volume; less water concentrates the peptide so small doses take fewer units.
| BAC water added | Concentration | 2 mg dose = units |
|---|---|---|
| 1 mL | 10 mg/mL | 20 units |
| 2 mL | 5 mg/mL | 40 units |
| 3 mL | 3.33 mg/mL | 60 units |
There is no single right answer — many people mixing a 10 mg retatrutide vial settle on 2 mL for a round 5 mg/mL. Whatever you choose, enter it in the calculator so the units and syringe diagram match your actual vial.
Common retatrutide dosing mistakes to avoid
The most frequent errors are mechanical, not clinical, and the calculator is designed to prevent them:
- Confusing mg with mL or units. Your dose is in milligrams, but the syringe is marked in units. Never draw "2" on the syringe for a 2 mg dose — that is 2 units, a tiny fraction. Always use the calculated unit value.
- Forgetting the concentration changed. If you add a different amount of water next time, every unit value changes. Re-run the calculator whenever you reconstitute a new retatrutide vial.
- Trying to fit a large dose in one syringe. At 5 mg/mL, anything over 5 mg exceeds a 100-unit syringe. Split the draw or mix at a higher concentration.
- Shaking the vial. Peptides degrade with agitation; swirl gently instead.
Using a prefilled retatrutide pen
If you have a prefilled pen (for example a 30 mg or 40 mg pen) rather than a vial, the pen dials the dose for you and no reconstitution is needed. This calculator is most useful for lyophilized retatrutide vials where you mix and draw manually. For pens, follow the click-to-mg mapping printed on your device.
A peptide calculator for tirzepatide and semaglutide too
The reconstitution math is the same for every lyophilized GLP peptide — only the numbers change. Switch the tab at the top of the calculator to run it as a tirzepatide dosage calculator or a semaglutide (Ozempic / Wegovy research) calculator. Each peptide loads its own typical vial sizes and a starting titration schedule, then the tool computes concentration, draw volume, U-100 units, and how many doses your vial holds.
Tirzepatide
Tirzepatide vials commonly come as 10 mg, 30 mg, or 60 mg. Titration often begins near 2.5 mg weekly and steps up every four weeks. Enter your vial and water volume and the calculator shows the exact units to draw.
Semaglutide
Semaglutide is dosed in much smaller amounts — often starting around 0.25 mg weekly — so precise unit measurement matters even more. The same reconstitution formula applies; the semaglutide tab preloads sensible defaults so you can see units at a glance.
Doses per vial — how long will it last?
Beyond a single injection, the calculator divides your total vial content by your dose to show how many doses the vial holds and, assuming once-weekly injections, roughly how many weeks it lasts. That makes it easy to plan reorders and compare the real cost per dose across vial sizes before you mix anything.
Frequently asked questions
How much bacteriostatic water do I add to a retatrutide vial?
It depends on the concentration you want. A popular choice for a 10 mg vial is 2 mL, which gives 5 mg/mL. Add less water for a stronger mix (fewer units per dose) or more for a weaker one. Enter your numbers above to see the exact result.
How do I convert my dose to units on the syringe?
Divide your dose (mg) by the concentration (mg/mL) to get the draw volume in mL, then multiply by 100. The calculator does this automatically and draws the fill line for you.
What is a typical weekly titration schedule?
A frequently cited ramp starts around 2 mg weekly and steps up every 4 weeks (4 mg, 8 mg, up to 12 mg). Slower titration generally means fewer side effects. Always follow clinical guidance.
Can I reuse this for tirzepatide or semaglutide?
The reconstitution and units math is identical for any lyophilized peptide — only the vial mg, water volume, and target dose change. Enter the values for your peptide and the calculator works the same way.
Why does the syringe show units instead of mL?
Because insulin syringes are labeled in units, not mL. Reading the unit line directly removes a conversion step and the errors that come with it.
Is there a retatrutide dosage chart I can follow?
Yes — the retatrutide dosage chart above shows draw volume and U-100 units for every dose from 1 mg to 12 mg at the common 5 mg/mL concentration. For any other vial size or water volume, the calculator generates your personal chart instantly.
How many units is 2 mg of retatrutide?
It depends entirely on your concentration. At 5 mg/mL (a 10 mg vial in 2 mL of water), 2 mg is 0.4 mL, which is 40 units on a U-100 syringe. Mix at a different concentration and the calculator updates the unit value.
Does this retatrutide calculator prescribe a dose?
No. It only converts a dose you enter into draw volume and syringe units. It does not recommend how much retatrutide to take — that decision belongs with a licensed healthcare professional.