Dose calculator

Retatrutide dose calculator

Convert any Retatrutide dose into syringe units in real time, pre-filled with a 10 mg / 2 mL example.

iPhone · Free to download

Last updated: May 13, 2026

Vial (mg)

Diluent (mL)

Dose (mg)

Dose unit

Draw on a U-100 syringe

40.0 units

Volume to draw

0.400 mL

Retatrutide is an experimental once-a-week injection people are tracking for weight loss and blood-sugar effects. It's the first triple agonist — it hits GLP-1, GIP, and glucagon receptors together, which appears to amplify both appetite suppression and energy expenditure. In a Phase 2 trial, adults with obesity lost about 24.2% of body weight at 48 weeks on the highest dose. It is still investigational and not approved. This page covers the reconstitution math and weekly logging cadence.

How the Retatrutide dose calculator works

Retatrutide is a triple agonist (GLP-1, GIP, glucagon), and trial doses ran from 1 mg to 12 mg weekly. On a 10 mg vial mixed with 2 mL water, a 2 mg dose pulls 40 units. Step up to 4 mg and that doubles to 80. The calculator tracks the units as your titration moves.

The formula is volume in mL equals dose mg divided by concentration mg/mL, then volume times one hundred to get units on a U-100 insulin syringe. With a 5 mg/mL Retatrutide solution and a 2 mg dose, the draw is 0.40 mL or about 40 units. Type any other dose and the unit count updates in real time — no spreadsheets, no guesswork.

Inputs that genuinely matter: concentration (which only changes when you reconstitute a new vial) and dose mass. Syringe type matters too, but only because U-100 vs U-40 changes the multiplier — almost every modern insulin syringe is U-100, which is why the math defaults to that. Edge cases worth flagging: switching from mcg to mg without checking the input unit, or carrying yesterday's unit count over to a new vial that was reconstituted with a different volume of BAC water.

Worked example

Walking one Retatrutide dose through the math

The vial holds 10 mg of Retatrutide, mixed into 2 mL of bacteriostatic water — concentration 5.00 mg/mL.
Your 2 mg dose ÷ 5.00 mg/mL = 0.400 mL of solution to pull.
Multiply by 100 (because U-100 means 100 units per mL): 0.400 × 100 = 40 units.
Double the dose to 4 mg and the unit count doubles to 80 — the relationship is linear at a fixed concentration.
Change the diluent volume and every one of these numbers moves; change the dose alone and only the last one does.

Retatrutide titration ladder at this concentration

What different Retatrutide dose steps draw on a U-100 insulin syringe at the example 5.00 mg/mL concentration.

Dose (mg)	Volume (mL)	Units (U-100)
1	0.200	20
2	0.400	40
4	0.800	80
8	1.600	160

Doubling the Retatrutide dose doubles the unit count. Halving it halves the count. Step-ups under 5 units are hard to read accurately — re-reconstitute with more water if your titration hits that range.

Scenarios people actually run into

Three things that come up logging Retatrutide

You're sitting at the 2 mg Retatrutide step and your prescriber bumps you up. The new dose is double — 80 units instead of 40. Same vial, same syringe, twice the volume on the line.
Your fingers reach for the syringe and the unit count from last week is still in your head. Half the time that number is fine; the other half, the vial changed and the right answer moved. The calculator is the second pair of eyes.
You skipped a week. Retatrutide cadence is 1 dose per week, and doubling up to "catch up" almost never reads how people expect — log the skip, then log the next normal dose.

Same-category neighbor

Retatrutide next to Tirzepatide

Both sit in the GLP-1 bucket — here's the dose math side by side on each one's example vial.

	Retatrutide	Tirzepatide
Example dose	2 mg	2.5 mg
Concentration	5.00 mg/mL	5.00 mg/mL
Units to draw	40	50

Want the full breakdown? Tirzepatide reference →

How Retatrutide dosing is tracked

Once-weekly subcutaneous injection is the default cadence in most retatrutide logs. Each draw is small enough that a U-100 insulin syringe is the standard tool — the volumes involved are too small to read accurately on a tuberculin syringe.

Because retatrutide is potent at small milligram counts, dose escalation tends to be gradual and well-tracked. The exact week and unit count of each step is the kind of information that is hard to reconstruct from memory months later, which is why a structured dose log is more durable than scattered notes.

Dosing schedules documented in published Phase 2 clinical trials for retatrutide have involved a notably steep titration. Study protocols have detailed starting doses that escalate at predetermined intervals to much higher terminal doses than those typical for related peptides. For example, a documented titration schedule involved monthly escalations from a starting dose, progressing through tiers such as 2 mg, 4 mg, 8 mg, and up to a 12 mg maximum dose, all administered on a weekly cadence. For personal tracking, these published trial schedules are the only available structural reference points for logging dose escalation over a period of months.

Common Retatrutide dose-calculation mistakes

Skipping the escalation date in the log, then losing the timeline of when each step actually occurred.
Neglecting to calculate injection volume for high-end doses, leading to logistical issues with standard 1 mL syringes.
Confusing retatrutide doses with semaglutide or tirzepatide doses — the milligram ranges differ and the math does not transfer.

Frequently asked questions about Retatrutide dose calculator

How does the Retatrutide dose calculator turn mg into syringe units?

It runs two divisions in sequence. First it computes concentration (vial mg ÷ diluent mL) — for the example here that's 10 ÷ 2 = 5.00 mg/mL. Then it divides your dose by that concentration to get volume in mL, and multiplies by 100 to convert volume into U-100 syringe units. The output updates as you type so you can sanity-check before drawing. Retatrutide trial titration stepped every 4 weeks, so an 8 mg target dose typically takes 4-5 vials to reach.

Does the Retatrutide dose calculator know which syringe I'm using?

It assumes a U-100 insulin syringe — the most common type for sub-cutaneous peptide injections. U-100 means 100 units per mL. If you're using a U-40 syringe (rare outside veterinary contexts) the unit count is wrong by a factor of 2.5. Tuberculin syringes read in mL directly, so on those just use the volume figure. Retatrutide trial titration stepped every 4 weeks, so an 8 mg target dose typically takes 4-5 vials to reach.

Why does the same Retatrutide dose pull a different unit count today than last week?

Because either the vial or the diluent volume changed. Concentration depends on both. A 5 mg vial reconstituted with 1 mL is twice as concentrated as the same vial with 2 mL — same dose, half the units. Whenever you open a fresh vial, run the dose math again rather than carrying the prior count over. Retatrutide trial titration stepped every 4 weeks, so an 8 mg target dose typically takes 4-5 vials to reach.

What if my Retatrutide dose lands at fewer than 5 units?

That's the calculator telling you the current vial is too concentrated for the dose you want. Five units on a U-100 syringe is hard to read accurately — the markings get tight. Reconstitute the next vial with more bacteriostatic water (commonly 2 mL instead of 1 mL) so each dose covers a larger, cleaner volume. Retatrutide trial titration stepped every 4 weeks, so an 8 mg target dose typically takes 4-5 vials to reach.

Related on Peptide Pilot

Log every Retatrutide dose in the app

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