Use this retatrutide dosage calculator to translate vial strength, BAC water volume, and target dose into a precise draw in mL and U-100 units. It covers 5, 10, 12, 15, 20, 24, 30 and 40 mg vials and focuses on the math, not on dosing recommendations.
- Common vial examples
- 5 / 10 / 20 / 30 mg
- Example dose
- 2 mg
- Common syringe
- U-100 insulin
- Last reviewed
Quick math example
A 10 mg vial mixed with 2 mL gives 5 mg/mL. A 2 mg dose is 0.4 mL, which equals 40 units on a U-100 syringe.
Retatrutide reconstitution reference
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 5 mg | 2.5 mg/mL | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 320 u(3.2 mL) | 480 u(4.8 mL) |
| 10 mg | 5 mg/mL | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 240 u(2.4 mL) |
| 20 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
| 30 mg | 15 mg/mL | 6.7 u(0.07 mL) | 13.3 u(0.13 mL) | 26.7 u(0.27 mL) | 53.3 u(0.53 mL) | 80 u(0.8 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How the retatrutide calculation works
Retatrutide doses are typically discussed in milligrams while many vials and syringes require thinking in mg, mcg, mL, and units at the same time. The calculator handles all four conversions for you.
Concentration is solved first, then your target dose is divided by that concentration to return the draw volume and matching syringe units.
- 10 mg equals 10,000 mcg
- 10,000 mcg / 2 mL = 5,000 mcg per mL
- 2,000 mcg / 5,000 mcg per mL = 0.4 mL
Retatrutide 10 mg vial with 2 mL example
A 10 mg retatrutide vial mixed with 2 mL gives 5 mg/mL, or 5,000 mcg/mL.
A 2 mg target dose is 2,000 mcg. At 5,000 mcg/mL that is 0.4 mL, which equals 40 units on a U-100 syringe.
- 10 mg / 2 mL = 5 mg/mL
- 2 mg = 2,000 mcg
- 2,000 mcg / 5,000 mcg per mL = 0.4 mL = 40 U-100 units
Retatrutide 5 mg vial with 2 mL example
A 5 mg retatrutide vial mixed with 2 mL gives 2.5 mg/mL, or 2,500 mcg/mL — half the concentration of the 10 mg example.
Because the vial is more dilute, the same 2 mg dose now needs 0.8 mL, which equals 80 units on a U-100 syringe. A lower-strength vial always pushes the draw volume higher.
- 5 mg / 2 mL = 2.5 mg/mL
- 2,000 mcg / 2,500 mcg per mL = 0.8 mL
- 0.8 mL x 100 = 80 U-100 units
Choosing BAC water for a retatrutide titration
Retatrutide protocols usually start low and step up over several weeks, so it helps to pick a reconstitution volume that keeps both early and later doses on readable unit marks. More bacteriostatic water lowers the concentration and raises the units drawn for the same dose.
For a 10 mg vial: 1 mL gives 10 mg/mL (a 2 mg dose = 0.2 mL = 20 units), 2 mL gives 5 mg/mL (2 mg = 0.4 mL = 40 units), and 4 mL gives 2.5 mg/mL (2 mg = 0.8 mL = 80 units).
- More BAC water = lower concentration = more units per dose
- Aim for early titration steps that still land on clear unit lines
- Re-run the math each time you step the dose up
Retatrutide dosage calculator in units: dose to U-100 units chart
On a U-100 insulin syringe, 100 units is 1 mL, so units are simply the draw volume in hundredths of a millilitre. At 5 mg/mL (a 10 mg vial in 2 mL) every 1 mg of retatrutide is 0.2 mL, which makes each titration step easy to remember: 1 mg = 20 units, 2 mg = 40 units, 4 mg = 80 units.
Above 5 mg per dose the draw at 5 mg/mL exceeds a 1 mL syringe, so either use a 3 mL syringe or reconstitute with less water (10 mg in 1 mL = 10 mg/mL halves every draw). The table below gives the units for each common dose and vial size at the default water volume; change the water in the calculator to recompute.
- 1 mg = 20 units · 2 mg = 40 units · 4 mg = 80 units (10 mg vial, 2 mL)
- 6 mg = 120 units at 5 mg/mL — use less water or a larger syringe
- At 10 mg/mL (10 mg in 1 mL): 1 mg = 10 units, 2 mg = 20 units, 8 mg = 80 units
Retatrutide units per dose by vial size (2 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 5 mg | 2.5 mg/mL | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 320 u(3.2 mL) | 480 u(4.8 mL) |
| 10 mg | 5 mg/mL | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 240 u(2.4 mL) |
| 20 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
| 30 mg | 15 mg/mL | 6.7 u(0.07 mL) | 13.3 u(0.13 mL) | 26.7 u(0.27 mL) | 53.3 u(0.53 mL) | 80 u(0.8 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 10 mg retatrutide vial
A 10 mg vial in 2 mL gives 5 mg/mL. A 2 mg dose is 0.4 mL, or 40 units on a U-100 syringe; a 4 mg dose at the same concentration is 0.8 mL, or 80 units. 2 mL is the usual choice because it keeps early titration doses on readable unit lines while still fitting a 1 mL syringe up to 5 mg.
A 10 mg vial covers most of the early-to-mid titration window in a single reconstitution. As doses climb past 6 mg per week it empties within a couple of weeks, at which point 1.5 mL of water (6.67 mg/mL) or a 20 mg vial keeps draws under 1 mL.
- 10 mg / 2 mL = 5 mg/mL → 2 mg = 40 units, 4 mg = 80 units
- 10 mg / 1 mL = 10 mg/mL → 2 mg = 20 units, 4 mg = 40 units
- Above ~6 mg per dose, use 1.5 mL of water to keep draws under 1 mL
Retatrutide 10 mg vial: units per dose (2 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 10 mg | 5 mg/mL | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 240 u(2.4 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 12 mg retatrutide vial
12 mg does not divide evenly into 2 mL, so the usual choice is 1.2 mL or 2.4 mL to land on round concentrations. 12 mg in 1.2 mL gives 10 mg/mL (2 mg = 20 units, 4 mg = 40 units); 12 mg in 2.4 mL gives 5 mg/mL (2 mg = 40 units, 4 mg = 80 units).
If you do use 2 mL, the vial is 6 mg/mL and the units stop being round: 2 mg is 0.33 mL (about 33 units) and 4 mg is 0.67 mL (about 67 units). A 12 mg vial holds about six 2 mg doses or three 4 mg doses.
- 12 mg / 1.2 mL = 10 mg/mL → 2 mg = 20 units, 4 mg = 40 units
- 12 mg / 2.4 mL = 5 mg/mL → 2 mg = 40 units, 4 mg = 80 units
- 12 mg / 2 mL = 6 mg/mL → 2 mg ≈ 33 units (harder to read)
Retatrutide 12 mg vial: units per dose (2.4 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2.4 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 12 mg | 5 mg/mL | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 240 u(2.4 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 15 mg retatrutide vial
A 15 mg vial in 3 mL gives the same 5 mg/mL as a 10 mg vial in 2 mL, so the unit math carries over: 2 mg = 40 units, 4 mg = 80 units. Using 1.5 mL instead gives 10 mg/mL and halves every draw (2 mg = 20 units).
A 15 mg vial holds about seven 2 mg doses, or three to four doses at 4 mg, before dead-space loss.
- 15 mg / 3 mL = 5 mg/mL → 2 mg = 0.4 mL = 40 units
- 15 mg / 1.5 mL = 10 mg/mL → 2 mg = 0.2 mL = 20 units
- 15 mg / 2 mL = 7.5 mg/mL → 2 mg = 0.27 mL = 27 units
Retatrutide 15 mg vial: units per dose (3 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 3 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 15 mg | 5 mg/mL | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 160 u(1.6 mL) | 240 u(2.4 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 20 mg retatrutide vial
A 20 mg vial in 2 mL gives 10 mg/mL: 2 mg is 0.2 mL (20 units) and 8 mg is 0.8 mL (80 units), so even the higher titration steps fit a 1 mL syringe. In 4 mL the vial is 5 mg/mL and the units double (2 mg = 40 units, 8 mg = 160 units, which needs a 3 mL syringe).
Most people reconstitute a 20 mg vial with 2 mL for that reason; use 4 mL only if your doses are small enough that a 10-unit draw is hard to read.
- 20 mg / 2 mL = 10 mg/mL → 2 mg = 20 units, 4 mg = 40 units, 8 mg = 80 units
- 20 mg / 4 mL = 5 mg/mL → 2 mg = 40 units, 4 mg = 80 units
- A 20 mg vial holds about ten 2 mg doses or five 4 mg doses
Retatrutide 20 mg vial: units per dose (2 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 20 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 24 mg retatrutide vial
A 24 mg vial in 2.4 mL gives 10 mg/mL, so the units match a 20 mg vial in 2 mL: 2 mg = 20 units, 4 mg = 40 units, 8 mg = 80 units. In 4.8 mL it is 5 mg/mL and every draw doubles (2 mg = 40 units).
With a round 2 mL the vial is 12 mg/mL and 2 mg becomes about 17 units, which is harder to read — that is why 2.4 mL is the common choice. A 24 mg vial holds about twelve 2 mg doses, six at 4 mg, or three at 8 mg.
- 24 mg / 2.4 mL = 10 mg/mL → 2 mg = 20 units, 8 mg = 80 units
- 24 mg / 4.8 mL = 5 mg/mL → 2 mg = 40 units, 4 mg = 80 units
- 24 mg / 2 mL = 12 mg/mL → 2 mg ≈ 17 units
Retatrutide 24 mg vial: units per dose (2.4 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 2.4 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 24 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 30 mg retatrutide vial
A 30 mg vial in 3 mL gives 10 mg/mL, the same concentration as 20 mg in 2 mL, so the per-dose units are identical: 2 mg = 20 units, 4 mg = 40 units, 8 mg = 80 units, 12 mg = 120 units. In 6 mL the vial is 5 mg/mL and every draw doubles.
A 30 mg vial is usually chosen by people already at higher maintenance doses; at 8 mg per dose it holds close to four doses, and at 12 mg two and a half. Check the vial's fill capacity before adding 6 mL — many 30 mg vials are 3 mL glass.
- 30 mg / 3 mL = 10 mg/mL → 2 mg = 20 units, 8 mg = 80 units, 12 mg = 120 units
- 30 mg / 6 mL = 5 mg/mL → 2 mg = 40 units, 8 mg = 160 units
- Check the vial's capacity before choosing a large water volume
Retatrutide 30 mg vial: units per dose (3 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 3 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 30 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
How much BAC water for a 40 mg retatrutide vial
A 40 mg vial in 4 mL gives 10 mg/mL, the same units as 20 mg in 2 mL: 2 mg = 20 units, 8 mg = 80 units, 12 mg = 120 units (more than a 1 mL syringe). In 2 mL it is 20 mg/mL and every draw halves: 2 mg = 10 units, 8 mg = 40 units, 12 mg = 60 units.
A 40 mg vial holds about twenty 2 mg doses or five 8 mg doses. At lower doses that can outlast the reconstituted beyond-use date, so check the date your pharmacy or label gives before mixing the whole vial.
- 40 mg / 4 mL = 10 mg/mL → 2 mg = 20 units, 8 mg = 80 units
- 40 mg / 2 mL = 20 mg/mL → 2 mg = 10 units, 12 mg = 60 units
- Plan around the beyond-use date, not just the dose count
Retatrutide 40 mg vial: units per dose (4 mL BAC water)
U-100 units to draw for each common Retatrutide dose, by vial size, reconstituted with 4 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 1 mg | 2 mg | 4 mg | 8 mg | 12 mg |
|---|---|---|---|---|---|---|
| 40 mg | 10 mg/mL | 10 u(0.1 mL) | 20 u(0.2 mL) | 40 u(0.4 mL) | 80 u(0.8 mL) | 120 u(1.2 mL) |
Swipe the table to see every dose →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.
Frequently asked questions
Does this calculator tell me what retatrutide dose to take?
How much BAC water should I use for a retatrutide vial?
Why does my retatrutide draw volume change with vial size?
Can PepSync track a retatrutide titration schedule?
How much BAC water do I add to a 30 mg retatrutide vial?
How many units is 2 mg of retatrutide?
How much BAC water for a 12 mg retatrutide vial?
How much BAC water for a 24 mg retatrutide vial?
Primary sources
Background references for this calculator. PepSync does not make clinical claims; these citations support the educational context only.