Retatrutide calculator (vial math, not a dose)

Last updated October 19, 2026. Reviewed by The Peptide Directory Editorial Team

A 10 mg retatrutide vial with 2 mL of diluent is 5 mg/mL, so 1 mg is 0.2 mL — 20 units on a U-100 syringe.

Also called: retatrutide dosage calculator, retatrutide units, retatrutide reconstitution.

Result

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Reference chart

Units on a U-100 syringe for an amount at four common vial/diluent combinations. Values over 100 units exceed a 1 mL syringe.
Amount (mg)	5 mg vial / 2 mL	10 mg vial / 2 mL	10 mg vial / 3 mL	20 mg vial / 2 mL
0.1	4 u	2 u	3 u	1 u
0.25	10 u	5 u	7.5 u	2.5 u
0.5	20 u	10 u	15 u	5 u
1	40 u	20 u	30 u	10 u
2	80 u	40 u	60 u	20 u
2.5	100 u	50 u	75 u	25 u
5	200 u	100 u	150 u	50 u

Retatrutide label steps expressed in syringe units

The FDA-approved product is a pen or single-dose device dosed in mg, so this conversion only applies when a vial is drawn with a U-100 syringe. Each mg step below is copied from the Retatrutide 12 mg in Phase 3 schedule; the units are arithmetic at three example concentrations.

Retatrutide: label mg steps as U-100 units at 2.5, 5, 10 mg/mL
Step	mg	at 2.5 mg/mL	at 5 mg/mL	at 10 mg/mL
Weeks 1–4	2	80 u	40 u	20 u
Weeks 5–8	4	over 1 mL	80 u	40 u
Weeks 9–12	6	over 1 mL	over 1 mL	60 u
Weeks 13–16	9	over 1 mL	over 1 mL	90 u
Week 17 onward	12	over 1 mL	over 1 mL	over 1 mL

Worked example

Example: 10 mg vial + 2 mL → 5 mg/mL; 1 mg ÷ 5 = 0.2 mL = 20 units.

How it works

1. Concentration
Divide the vial content (mg) by the diluent volume (mL) to get mg/mL.
2. Volume
Divide the amount you need (mg) by the concentration to get mL.
3. Syringe units
Multiply mL by 100 for units on a U-100 syringe.

Frequently asked questions

How do I calculate Retatrutide units?

Concentration = vial mg ÷ diluent mL; volume = amount ÷ concentration; units = volume × 100 on a U-100 syringe.

Does the amount of water change the dose?

No. Water only changes concentration, and therefore how many units hold a given amount. The amount in the vial is fixed.

What is the retatrutide dose?

Retatrutide is investigational and has no approved dose. Trial schedules (e.g. TRIUMPH) are reproduced with sources on our retatrutide protocol page; this calculator only does arithmetic.

Does this calculator recommend a dose?

No. It converts numbers you enter. Dosing decisions belong to a licensed clinician.

Sources

Reconstitution, units and concentration arithmetic: see our lab-handling guide, The Peptide Directory

Label and trial dose references

See the Retatrutide profile and Retatrutide prices per mg. For doses as printed in FDA labels or used in trials, see the peptide dose reference and the protocol pages.

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