Retatrutide Dosage Chart: Vial Size to Syringe Units

A retatrutide dosage chart maps a vial's labeled mg amount and the bacteriostatic water added to it into the number that matters at the syringe: units. Retatrutide ships as lyophilized powder, so the mg on the label is fixed, but concentration is not — it depends entirely on how much water goes into the vial. This chart works through that math for the vial sizes retatrutide is commonly supplied in. It is a reference for research and educational purposes only and is not medical advice.

The reference concentration

There is no single required water volume for retatrutide. A reference point commonly cited across retatrutide research materials scales the water to the vial size at 1 mL per 10 mg, which holds the concentration at a constant 10 mg/mL no matter which vial size is on hand:

Vial size	Water added	Concentration
10 mg	1 mL	10 mg/mL
15 mg	1.5 mL	10 mg/mL
20 mg	2 mL	10 mg/mL
30 mg	3 mL	10 mg/mL

Because the ratio scales with vial size, the units for a given dose stay identical across all four rows — only the total number of doses each vial holds changes. For the full mixing procedure behind these numbers, see the retatrutide reconstitution calculator guide.

Retatrutide dosage chart by target dose

Each row below assumes the 10 mg/mL reference concentration and shows the resulting draw on a U-100 insulin syringe (100 units per mL):

Target dose	Volume	Units
1 mg	0.1 mL	10 units
2 mg	0.2 mL	20 units
3 mg	0.3 mL	30 units
4 mg	0.4 mL	40 units
6 mg	0.6 mL	60 units
8 mg	0.8 mL	80 units

A 1 mg dose landing on an exact 10-unit mark is the reason 10 mg/mL is the reference concentration most retatrutide charts default to — every whole-mg dose in the table above reads cleanly on a standard U-100 barrel.

Reading the chart against a specific vial

Worked example. A 20 mg vial mixed with 2 mL of bacteriostatic water sits at 20 ÷ 2 = 10 mg/mL. For a 4 mg target dose: 4 ÷ 10 = 0.4 mL, and 0.4 mL × 100 = 40 units on a U-100 syringe.

Compare that to the same 4 mg dose drawn from a 10 mg vial mixed with 1 mL of water — also 10 mg/mL: 4 ÷ 10 = 0.4 mL, or 40 units again. The dose in mg is identical, and so is the unit reading, because both vials were reconstituted to the same concentration. What differs is supply: the 10 mg vial holds 10 ÷ 4 = 2.5 doses at 4 mg each, while the 20 mg vial holds 20 ÷ 4 = 5 doses. For the total-mg and doses-per-vial side of that question, see the retatrutide vial size guide.

Vial size sets dose count, water volume sets draw size

Vial size and water volume do different jobs, and conflating them is the most common misread of a chart like this one. Vial size sets the total mg of retatrutide available across the whole vial. Water volume sets concentration, which is what determines the units for any single draw.

At a 2 mg dose, a 15 mg vial provides 15 ÷ 2 = 7.5 doses. A 30 mg vial at that same 2 mg dose provides 30 ÷ 2 = 15 doses — twice the doses, because it holds twice the retatrutide, not because it was mixed differently. Water volume, by contrast, changes only the draw size per dose, not how many doses the vial holds in total.

When your vial doesn't match the reference ratio

A vial mixed with a different water volume still follows the same formula — it just won't land on the chart above. Take a 15 mg vial mixed with 1 mL of water instead of the reference 1.5 mL: concentration is 15 ÷ 1 = 15 mg/mL. A 4 mg target dose at that concentration is 4 ÷ 15 = 0.2667 mL, or roughly 26.7 units — a fractional reading that doesn't sit cleanly on a syringe marked in whole units.

That's a signal to change the water volume rather than round the draw up or down. This is the case the peptide calculator is built for: enter the vial size and water volume you actually used, and it runs the same concentration-to-units math for any combination, not just the round numbers in a reference chart. Its reverse mode also works the other direction — enter a target dose and a desired unit reading, and it returns the water volume that produces it.

Common mistakes

• Reading a unit count from this retatrutide dosage chart against the wrong vial. A number in the table only applies if the vial was actually mixed to the 10 mg/mL reference concentration. Confirm the water volume used before drawing.
• Assuming vial size sets the dose. It sets the total mg available across the vial. Concentration — set by water volume — is what determines units per dose.
• Mixing up mg and mcg. Retatrutide vials and doses are generally labeled in milligrams, not micrograms (1 mg = 1,000 mcg). A missed decimal here is a thousand-fold error.
• Rounding mid-calculation. Carry the full decimal through the mL step and only round the final unit reading, and only if the syringe requires it.

Use the calculator

This retatrutide dosage chart covers the common 10 mg/mL reference concentration, but your vial and target dose may not match it exactly. Enter your vial size, water volume, and target dose into the free peptide calculator for an exact unit count, or run its reverse mode to find the water volume that lands a given dose on a whole unit mark. For the step-by-step mixing process, see how to reconstitute peptides, and for how vial size translates into total doses per vial, see the retatrutide vial size guide.