Retatrutide Units Per mL Calculator

Retatrutide vials are labeled in milligrams, but the number that actually matters at the syringe is units per mL — and that figure never changes. A U-100 insulin syringe is built to read 100 units per mL, full stop. What changes with your reconstitution choice is how much retatrutide sits inside each of those units. This is a research reference for that math: how vial concentration sets mg per unit, and how to turn a target dose into an exact draw. It is written for research purposes only and is not medical advice.

What "units per mL" actually means

Every U-100 insulin syringe divides 1 mL into 100 units. That ratio is printed on the barrel and doesn't move — it's a property of the syringe, not the peptide. Searching for a retatrutide units per mL calculator usually isn't really asking about the syringe scale; it's asking a different question in disguise: given how I mixed this vial, how much retatrutide is in each unit, and how many units does my target dose take?

What changes: mg per unit

Concentration is vial mass divided by water volume. Once you know mg/mL, dividing by 100 gives mg per unit — the number that actually drives your draw.

For a 20 mg retatrutide vial:

Water added	Concentration	mg per unit	Units per mL
1 mL	20 mg/mL	0.2 mg/unit	100
2 mL	10 mg/mL	0.1 mg/unit	100
4 mL	5 mg/mL	0.05 mg/unit	100

Units per mL never leaves 100. Mg per unit drops as water volume rises, which is the entire lever you're pulling when you choose a reconstitution ratio.

Common retatrutide vial sizes

Research suppliers typically list retatrutide vials in 10 mg, 15 mg, 20 mg, and 30 mg. The units-per-mL logic on this page holds for any of them — only the mg-per-unit figure shifts with vial size and water volume.

Worked example

20 mg vial + 2 mL bacteriostatic water → 10 mg/mL

• mg per unit: 10 ÷ 100 = 0.1 mg/unit
• 2 mg dose ÷ 0.1 mg/unit = 20 units
• 4 mg dose ÷ 0.1 mg/unit = 40 units

20 mg vial + 4 mL bacteriostatic water → 5 mg/mL

• mg per unit: 5 ÷ 100 = 0.05 mg/unit
• 2 mg dose ÷ 0.05 mg/unit = 40 units
• 4 mg dose ÷ 0.05 mg/unit = 80 units

Same 2 mg dose, same syringe, two different unit readings — 20 units versus 40 — because the vials were mixed at different concentrations. Enter your own vial size and water volume into the free peptide calculator to skip this arithmetic, or use reverse mode to find the water volume that lands your usual dose on a round number.

Total doses per vial doesn't change

Water volume changes the units per dose. It does not change how much retatrutide is in the vial or how many doses that vial holds. A 20 mg vial at a 2 mg dose provides 10 doses whether it was reconstituted in 1 mL, 2 mL, or 4 mL — only the draw size per dose shifts:

Water added	Units for a 2 mg dose	Doses in the vial
1 mL	10 units	10
2 mL	20 units	10
4 mL	40 units	10

Choosing a ratio for a clean reading

None of the rows above is wrong — 20 mg of total retatrutide splits into 10 doses either way. What differs is how easy the draw is to read and double-check. A dose that lands on 20 or 40 units is generally easier to draw accurately on a U-100 syringe than one that lands on a fraction of a unit, simply because small errors matter proportionally more at the low end and the barrel is easier to read at whole-number marks. The retatrutide reconstitution calculator guide walks through picking a water volume that keeps a specific target dose on a clean number across the common 10, 15, 20, and 30 mg vial sizes.

Reconstitution steps

1. Gather the retatrutide vial, bacteriostatic water, alcohol swabs, and a U-100 insulin syringe.
2. Swab both vial stoppers with alcohol.
3. Draw the water volume your chosen ratio calls for.
4. Inject it slowly down the inside wall of the vial, not directly onto the powder.
5. Swirl gently until fully dissolved — don't shake.
6. Confirm the resulting concentration matches what you entered into the calculator before drawing a dose.

For the general mixing process and storage notes, see how to reconstitute peptides.

Common mistakes

• Treating "units per mL" as if it varies by peptide or concentration. It doesn't — it's fixed at 100 on a U-100 syringe. The number that actually varies is mg per unit.
• Reusing a mg-per-unit figure across a different water volume. Change the water, and the mg-per-unit figure has to be recalculated — it doesn't carry over from a previous mix.
• Confusing a smaller unit count with a smaller dose. In the worked example above, 20 units and 40 units can both deliver a 4 mg dose at different concentrations — the unit count only reflects the concentration used, not the amount of retatrutide delivered.
• Mixing up mg and mcg. Retatrutide is generally labeled and dosed in milligrams, not micrograms (1 mg = 1000 mcg). Confirm which unit the vial label and target dose are both using before doing any conversion.
• Using a syringe that isn't U-100. Every calculation here assumes 100 units = 1 mL. A different syringe scale changes the unit conversion.

Use the calculator

Enter your retatrutide vial size and water volume into the peptide calculator to get concentration, mg per unit, and the exact syringe units for any target dose. Reverse mode runs it the other way — enter your dose and the units you want to land on, and it returns the water volume that gets you there.

For related math, see the retatrutide dosage calculator guide. The calculator does the arithmetic; this guide explains what the units on the syringe actually represent.