Retatrutide units chart: doses in units for every common vial

Your dose is set in mg. Units are just how much liquid carries that dose, and that depends on how much water went into the vial. 2 mg from a 10 mg vial mixed with 1 mL is a different number of units than 2 mg from the same vial mixed with 2 mL. Copying someone else's unit count without their vial and water volume is how people end up on the wrong dose.

So find your vial and water volume below, or put them into the reconstitution calculator. The method is explained in mg to units conversion.

Retatrutide is not approved, so there is no label dose. The rows come from the trials and from community practice:

• Trials: 2 mg once a week to start, stepping up every 4 weeks. Phase 3 (TRIUMPH) targets 4, 9 or 12 mg. Phase 2 tested 1, 4, 8 and 12 mg, with the 4, 8 and 12 mg arms mostly starting at 2 mg. Dosing guides describe the phase 3 ladder as 2, 4, 6, 9, then 12 mg.
• Community: On r/Retatrutide, 1 mg a week is the most common start, and some begin at 0.5 mg. These are self-reports, not trial doses.

That gives the rows 0.5, 1, 2, 4, 6, 8, 9 and 12 mg. The retatrutide page has the full dosing picture and sources.

Guides use these volumes:

• 5 mg vial: 1 mL, or 2 mL for small doses
• 10 mg vial: 1 mL or 2 mL
• 12 mg vial: 1.2 mL
• 15 mg vial: 1 mL or 2 mL, with 2 mL called the community standard
• 20 mg vial: 2 mL, 3 mL or 4 mL
• 30 mg vial: 3 mL

Many land on 10 mg per mL (1 mL per 10 mg of powder), which keeps doses up to 9 mg inside one 1 mL syringe. More water makes small doses easier to measure and big doses bulkier. One r/Retatrutide poster mixes a 20 mg vial with 3 mL and climbs in small weekly steps from that mix.

Whatever you choose, write the volume on the vial and use the matching chart.

A 5 mg vial only holds enough for the low doses, so rows above 5 mg are not listed.

5 mg vial + 1 mL water (5 mg/mL)

• 0.5 mg: 10 units (0.1 mL)
• 1 mg: 20 units (0.2 mL)
• 2 mg: 40 units (0.4 mL)
• 4 mg: 80 units (0.8 mL)

5 mg vial + 2 mL water (2.5 mg/mL)

• 0.5 mg: 20 units (0.2 mL)
• 1 mg: 40 units (0.4 mL)
• 2 mg: 80 units (0.8 mL)
• 4 mg: 160 units (1.6 mL) more than one full 1 mL syringe

Both mixes are common.

10 mg vial + 1 mL water (10 mg/mL)

• 0.5 mg: 5 units (0.05 mL)
• 1 mg: 10 units (0.1 mL)
• 2 mg: 20 units (0.2 mL)
• 4 mg: 40 units (0.4 mL)
• 6 mg: 60 units (0.6 mL)
• 8 mg: 80 units (0.8 mL)
• 9 mg: 90 units (0.9 mL)

10 mg vial + 2 mL water (5 mg/mL)

• 0.5 mg: 10 units (0.1 mL)
• 1 mg: 20 units (0.2 mL)
• 2 mg: 40 units (0.4 mL)
• 4 mg: 80 units (0.8 mL)
• 6 mg: 120 units (1.2 mL) more than one full 1 mL syringe
• 8 mg: 160 units (1.6 mL) more than one full 1 mL syringe
• 9 mg: 180 units (1.8 mL) more than one full 1 mL syringe

With 2 mL, doses from 6 mg up need more than one full 1 mL syringe, while 1 mL keeps every dose up to 9 mg in one syringe. With 1 mL, the 0.5 mg dose is only a few units, which is hard to read on a 1 mL syringe; a 0.3 mL or 0.5 mL syringe helps.

The volume dosing guides list for a 12 mg vial is 1.2 mL.

12 mg vial + 1.2 mL water (10 mg/mL)

• 0.5 mg: 5 units (0.05 mL)
• 1 mg: 10 units (0.1 mL)
• 2 mg: 20 units (0.2 mL)
• 4 mg: 40 units (0.4 mL)
• 6 mg: 60 units (0.6 mL)
• 8 mg: 80 units (0.8 mL)
• 9 mg: 90 units (0.9 mL)
• 12 mg: 120 units (1.2 mL) more than one full 1 mL syringe

A full 12 mg dose uses the whole vial in one week and is more than one 1 mL syringe.

Both 1 mL and 2 mL are listed for a 15 mg vial.

15 mg vial + 2 mL water (7.5 mg/mL)

• 0.5 mg: 6.7 units (0.067 mL)
• 1 mg: 13.3 units (0.133 mL)
• 2 mg: 26.7 units (0.267 mL)
• 4 mg: 53.3 units (0.533 mL)
• 6 mg: 80 units (0.8 mL)
• 8 mg: 106.7 units (1.067 mL) more than one full 1 mL syringe
• 9 mg: 120 units (1.2 mL) more than one full 1 mL syringe
• 12 mg: 160 units (1.6 mL) more than one full 1 mL syringe

15 mg vial + 1 mL water (15 mg/mL)

• 0.5 mg: 3.3 units (0.033 mL)
• 1 mg: 6.7 units (0.067 mL)
• 2 mg: 13.3 units (0.133 mL)
• 4 mg: 26.7 units (0.267 mL)
• 6 mg: 40 units (0.4 mL)
• 8 mg: 53.3 units (0.533 mL)
• 9 mg: 60 units (0.6 mL)
• 12 mg: 80 units (0.8 mL)

These mixes give fractions of a unit, and a 1 mL syringe only has a line every 2 units. A 0.3 mL or 0.5 mL syringe has a line every unit, so the small doses land much closer to a mark. At 1 mL the low doses are very small volumes, so 2 mL is easier for anyone still titrating.

20 mg vial + 2 mL water (10 mg/mL)

• 0.5 mg: 5 units (0.05 mL)
• 1 mg: 10 units (0.1 mL)
• 2 mg: 20 units (0.2 mL)
• 4 mg: 40 units (0.4 mL)
• 6 mg: 60 units (0.6 mL)
• 8 mg: 80 units (0.8 mL)
• 9 mg: 90 units (0.9 mL)
• 12 mg: 120 units (1.2 mL) more than one full 1 mL syringe

20 mg vial + 3 mL water (6.667 mg/mL)

• 0.5 mg: 7.5 units (0.075 mL)
• 1 mg: 15 units (0.15 mL)
• 2 mg: 30 units (0.3 mL)
• 4 mg: 60 units (0.6 mL)
• 6 mg: 90 units (0.9 mL)
• 8 mg: 120 units (1.2 mL) more than one full 1 mL syringe
• 9 mg: 135 units (1.35 mL) more than one full 1 mL syringe
• 12 mg: 180 units (1.8 mL) more than one full 1 mL syringe

20 mg vial + 4 mL water (5 mg/mL)

• 0.5 mg: 10 units (0.1 mL)
• 1 mg: 20 units (0.2 mL)
• 2 mg: 40 units (0.4 mL)
• 4 mg: 80 units (0.8 mL)
• 6 mg: 120 units (1.2 mL) more than one full 1 mL syringe
• 8 mg: 160 units (1.6 mL) more than one full 1 mL syringe
• 9 mg: 180 units (1.8 mL) more than one full 1 mL syringe
• 12 mg: 240 units (2.4 mL) more than one full 1 mL syringe

The 3 mL mix gives odd numbers per mg but finer steps between doses. If you want a 12 mg dose in a single draw from a 20 mg vial, guides suggest less water, such as 1 mL; run that through the calculator.

30 mg vial + 3 mL water (10 mg/mL)

• 0.5 mg: 5 units (0.05 mL)
• 1 mg: 10 units (0.1 mL)
• 2 mg: 20 units (0.2 mL)
• 4 mg: 40 units (0.4 mL)
• 6 mg: 60 units (0.6 mL)
• 8 mg: 80 units (0.8 mL)
• 9 mg: 90 units (0.9 mL)
• 12 mg: 120 units (1.2 mL) more than one full 1 mL syringe

This is the same strength as a 10 mg vial with 1 mL, so the units match that chart.

1. Swab both stoppers with separate alcohol swabs and let them dry.
2. Draw the water into a syringe that holds the whole volume, such as a 3 mL syringe. A 1 mL insulin syringe would take several draws.
3. Aim the needle at the inside wall of the vial and let the water run down the glass, not onto the powder.
4. Swirl gently until it dissolves, usually a few minutes. Never shake.
5. Check that it is clear and colorless. Label it with the name, strength and date.
6. Store it upright in the fridge at 2 to 8 C, use it within 28 days, and do not freeze it.

Use bacteriostatic water, not sterile water, for a vial you will draw from for weeks. More detail is in how to reconstitute peptides.

• Using the water volume meant for another vial. Switching from a 10 mg to a 20 mg vial with the same water doubles the strength. Recalculate before the first shot from a new vial.
• Copying unit counts. "I take 20 units" is meaningless without a vial size and water volume.
• Reading units as mg or IU. Syringe units are volume: 100 units is 1 mL.
• An oversized syringe for a tiny dose. FDA has collected reports of 5 to 20 times the intended dose of compounded semaglutide, with unit mix-ups and oversized syringes among the causes.
• No label on the vial. Mixed retatrutide looks like every other clear peptide.