Retatrutide calculator

Enter the mg on the vial, the water you added and the dose in mg, and see where to draw on your syringe. Below: the doses studied in trials, and where approval stands.

Have you mixed your vial with water yet?

How much retatrutide is in the vial?

It's printed on the vial label, for example 10mg. This is the powder before any water goes in.

Where is it on the label?

The amount is the big figure on the label, in mg. Ignore the volume of water or the batch number.

What dose were you told to take?

Use the number and unit exactly as you were given it. Doses under 1 mg are usually written in mcg (micrograms). 1 mg is 1,000 mcg.

How much water did you add?

Bacteriostatic water, in mL. If you're not sure, check what you wrote down when you mixed it.

Which syringe do you have?

Look at the biggest number printed on the side of the syringe.

Not sure? See the three sizes

All three are U-100 insulin syringes: 100 units is 1 mL. The top mark tells you which one you have. A 1 mL syringe has a line every 2 units, so count carefully.

Draw to

40 units

Pull the plunger back until the edge of the dark stopper nearest the needle lines up with 40. That's the line with 40 printed next to it.

Reading it back: 10 mg vial, mixed with 2 mL water, dose of 2 mg. That's 0.4 mL, and the vial holds about 5 doses.

Everything adds up. This fits your syringe and sits on a line you can read.

Show the maths

strength = 10 mg ÷ 2 mL = 5 mg/mL
volume = 2 mg ÷ 5 mg/mL = 0.4 mL
units = 0.4 mL × 100 = 40 units

Every dose from this vial

10 mg in 2 mL on a 1 mL syringe, in 0.5 mg steps. Your dose is whatever you were given; this only converts it.
Dose	Volume	Units	On the syringe
0.5 mg	0.1 mL	10	on a line
1 mg	0.2 mL	20	on a line
1.5 mg	0.3 mL	30	on a line
2 mg	0.4 mL	40	on a line
2.5 mg	0.5 mL	50	on a line
3 mg	0.6 mL	60	on a line
3.5 mg	0.7 mL	70	on a line
4 mg	0.8 mL	80	on a line
4.5 mg	0.9 mL	90	on a line
5 mg	1 mL	100	on a line
5.5 mg	1.1 mL	over 100	needs a bigger syringe
6 mg	1.2 mL	over 100	needs a bigger syringe
6.5 mg	1.3 mL	over 100	needs a bigger syringe
7 mg	1.4 mL	over 100	needs a bigger syringe
7.5 mg	1.5 mL	over 100	needs a bigger syringe
8 mg	1.6 mL	over 100	needs a bigger syringe
8.5 mg	1.7 mL	over 100	needs a bigger syringe
9 mg	1.8 mL	over 100	needs a bigger syringe
9.5 mg	1.9 mL	over 100	needs a bigger syringe
10 mg	2 mL	over 100	needs a bigger syringe

Printed from DoseClear. Reopen this exact answer:

Next time it opens with your numbers. Stays on this device.

This is a maths tool, not medical advice. If anything here doesn't match what you were told, check with your prescriber or pharmacist before you go ahead. Found an error?

Divide the mg in the vial by the mL of water to get the strength, then divide the dose by the strength and multiply by 100 for units. Example: 10 mg of retatrutide with 2 mL of water is 5 mg/mL, so 2 mg is 0.4 mL, or 40 units on a U-100 syringe.

Every step is shown

Open "Show the maths" and you can check each line yourself, or show it to someone you trust.

We catch the common slips

Mixing up mg and mcg, or picking the wrong syringe, are the usual mistakes. We flag both before you draw.

Nothing to sell you

No shop, no seller links, no account. Your numbers stay on your device.

Is retatrutide FDA approved?

Not approved As of 2026-10-07, retatrutide is not approved by the FDA for any use. It is an investigational medicine made by Eli Lilly and is in phase 3 trials (the TRIUMPH programme, for example NCT05929066). Lilly has also registered a pre-approval expanded access programme (NCT07629401).

Retatrutide sold outside a trial or Lilly's programme is not an approved product. Its strength and purity can't be checked from the label, which is one more reason to check your maths twice.

Doses studied in trials

In the published phase 2 trial, adults with obesity took retatrutide once a week for 48 weeks at one of these doses. Several groups started lower and stepped up. This is what was studied, not a recommendation.

Trial group	Weekly dose
Low	1 mg
Middle	4 mg (two groups: started at 2 mg, or at 4 mg)
Higher	8 mg (two groups: started at 2 mg, or at 4 mg)
Highest	12 mg (started at 2 mg)

How much water for a 10 mg vial?

Any amount works as long as you use the same number when you calculate. Here's what 2 mg looks like on a 1 mL syringe for common choices:

2 mg on a 1 mL U-100 syringe
Vial	Water	Strength	2 mg is	Doses per vial
10 mg	1 mL	10 mg/mL	20 units (0.2 mL)	5
10 mg	2 mL	5 mg/mL	40 units (0.4 mL)	5
10 mg	3 mL	3.33 mg/mL	60 units (0.6 mL)	5

Not mixed yet? The reconstitution calculator shows which water amounts land on a line.

Sources

Jastreboff AM et al. Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. N Engl J Med 2023;389:514-526: nejm.org
TRIUMPH-1 phase 3 trial record: clinicaltrials.gov
Pre-approval expanded access of retatrutide: clinicaltrials.gov

Last checked 2026-10-07.

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