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Retatrutide is an investigational medicine. It isn't approved by the FDA for any use, and there's no legal prescription version you can get from a pharmacy. Eli Lilly, which is developing it, says it plans to submit an application to the FDA in the first quarter of 2027 (Lilly Q2 2026 results).
The FDA states that "Retatrutide and cagrilintide cannot be used in compounding under federal law," and it has warned companies selling retatrutide labelled "for research purposes" or "not for human consumption" (FDA). So a vial of retatrutide powder sold online today isn't coming from a licensed pharmacy filling a lawful prescription. We don't recommend buying it.
Right now the legitimate routes are clinical trials and, for a very narrow group of patients, Lilly's expanded access program, which is arranged through a treating physician. If you're in a trial, follow your study team's instructions over anything on this page.
This calculator doesn't suggest a dose. It converts an amount into syringe units so you can understand and double-check the numbers you've been given.
Step 1: Enter your vial size in mg. Use the amount printed on the vial label. If yours isn't one of the presets, type it in.
Step 2: Enter the diluent volume. This is how much bacteriostatic water (or other diluent) went into the vial. The same vial mixed with a different volume gives a different number of units for the same dose.
Step 3: Choose your syringe. Doses in mg can add up to a large volume at low concentrations. A 1 mL (100 unit) syringe is selected by default so the result doesn't overflow.
Step 4: Enter the amount in mg. The presets are shortcuts for round numbers, not recommendations.
With the defaults shown, a 10 mg vial mixed with 2 mL is 5 mg/mL, so 2 mg is 0.4 mL, or 40 units. Mix the same vial with 1 mL and 2 mg is 20 units.
On a U-100 syringe, 100 units is always 1 mL. How much retatrutide sits in those units depends on your concentration.
2.5 mg/mL is a 5 mg vial in 2 mL, 5 mg/mL is a 10 mg vial in 2 mL, and 10 mg/mL is a 20 mg vial in 2 mL. The formula is: units = amount in mg ÷ concentration in mg/mL × 100.
The FDA has reported people taking several times their intended dose of compounded GLP-1 drugs because of mix-ups between mg, mL, and units (FDA alert). The same mistake is easy to make with retatrutide, so never carry a unit count over when your vial or diluent volume changes.
For what retatrutide is, where the trials stand, and how it compares with semaglutide and tirzepatide, see our guide on how to reconstitute retatrutide. The general peptide calculator covers other peptides, and PeptideKit can track each weekly dose and its side effects.
Divide the vial's mg by the mL of diluent to get the concentration in mg/mL. Divide your amount by that concentration to get mL, then multiply by 100 for units on a U-100 syringe. The calculator does all three steps.
At 5 mg/mL (10 mg in 2 mL), 2 mg is 40 units. At 10 mg/mL, it's 20 units. At 2.5 mg/mL, it's 80 units. This is a conversion example, not a suggested dose.
10 units is 0.1 mL. At 5 mg/mL that's 0.5 mg, and at 10 mg/mL it's 1 mg.
"GLP-3" is an online nickname, not a scientific term. Retatrutide is a triple agonist of the GIP, GLP-1, and glucagon receptors. Products marketed as "GLP-3" are a sign of a seller, not a prescription.
No. The FDA says retatrutide can't be used in compounding under federal law. Until it's approved, the legitimate ways to get it are a clinical trial or Lilly's expanded access program.
Always consult with qualified healthcare professionals before starting any peptide therapy protocol. This information is for educational purposes only and does not constitute medical advice.
Retatrutide Dosage Calculator
Enter your retatrutide vial size, how much diluent was added, and the amount you were told to take in mg. The calculator shows how many units to draw on a U-100 insulin syringe.
Peptide Amount in Vial
BAC Water
Syringe
Target Dose
Use the dose on your prescription. Presets are shortcuts, not recommendations.
Unit Rounding
Round the result to a whole or half unit mark you can read on your syringe.
Peptide Amount (Total in Vial)
Desired Concentration
Read This First: Retatrutide Is Not an Approved Drug
Retatrutide is an investigational medicine. It isn't approved by the FDA for any use, and there's no legal prescription version you can get from a pharmacy. Eli Lilly, which is developing it, says it plans to submit an application to the FDA in the first quarter of 2027 (Lilly Q2 2026 results).
The FDA states that "Retatrutide and cagrilintide cannot be used in compounding under federal law," and it has warned companies selling retatrutide labelled "for research purposes" or "not for human consumption" (FDA). So a vial of retatrutide powder sold online today isn't coming from a licensed pharmacy filling a lawful prescription. We don't recommend buying it.
Right now the legitimate routes are clinical trials and, for a very narrow group of patients, Lilly's expanded access program, which is arranged through a treating physician. If you're in a trial, follow your study team's instructions over anything on this page.
This calculator doesn't suggest a dose. It converts an amount into syringe units so you can understand and double-check the numbers you've been given.
How to Use the Retatrutide Calculator
Step 1: Enter your vial size in mg. Use the amount printed on the vial label. If yours isn't one of the presets, type it in.
Step 2: Enter the diluent volume. This is how much bacteriostatic water (or other diluent) went into the vial. The same vial mixed with a different volume gives a different number of units for the same dose.
Step 3: Choose your syringe. Doses in mg can add up to a large volume at low concentrations. A 1 mL (100 unit) syringe is selected by default so the result doesn't overflow.
Step 4: Enter the amount in mg. The presets are shortcuts for round numbers, not recommendations.
With the defaults shown, a 10 mg vial mixed with 2 mL is 5 mg/mL, so 2 mg is 0.4 mL, or 40 units. Mix the same vial with 1 mL and 2 mg is 20 units.
Retatrutide Units to mg Conversion Table
On a U-100 syringe, 100 units is always 1 mL. How much retatrutide sits in those units depends on your concentration.
| Syringe units | Volume | At 2.5 mg/mL | At 5 mg/mL | At 10 mg/mL |
|---|---|---|---|---|
| 10 units | 0.1 mL | 0.25 mg | 0.5 mg | 1 mg |
| 20 units | 0.2 mL | 0.5 mg | 1 mg | 2 mg |
| 40 units | 0.4 mL | 1 mg | 2 mg | 4 mg |
| 60 units | 0.6 mL | 1.5 mg | 3 mg | 6 mg |
| 80 units | 0.8 mL | 2 mg | 4 mg | 8 mg |
| 100 units | 1 mL | 2.5 mg | 5 mg | 10 mg |
The FDA has reported people taking several times their intended dose of compounded GLP-1 drugs because of mix-ups between mg, mL, and units (FDA alert). The same mistake is easy to make with retatrutide, so never carry a unit count over when your vial or diluent volume changes.
For what retatrutide is, where the trials stand, and how it compares with semaglutide and tirzepatide, see our guide on how to reconstitute retatrutide. The general peptide calculator covers other peptides, and PeptideKit can track each weekly dose and its side effects.
Frequently Asked Questions
How do I calculate retatrutide units?
Divide the vial's mg by the mL of diluent to get the concentration in mg/mL. Divide your amount by that concentration to get mL, then multiply by 100 for units on a U-100 syringe. The calculator does all three steps.
How many units is 2 mg of retatrutide?
At 5 mg/mL (10 mg in 2 mL), 2 mg is 40 units. At 10 mg/mL, it's 20 units. At 2.5 mg/mL, it's 80 units. This is a conversion example, not a suggested dose.
How much retatrutide is in 10 units?
10 units is 0.1 mL. At 5 mg/mL that's 0.5 mg, and at 10 mg/mL it's 1 mg.
Is retatrutide the same as "GLP-3"?
"GLP-3" is an online nickname, not a scientific term. Retatrutide is a triple agonist of the GIP, GLP-1, and glucagon receptors. Products marketed as "GLP-3" are a sign of a seller, not a prescription.
Can a pharmacy compound retatrutide?
No. The FDA says retatrutide can't be used in compounding under federal law. Until it's approved, the legitimate ways to get it are a clinical trial or Lilly's expanded access program.
Always consult with qualified healthcare professionals before starting any peptide therapy protocol. This information is for educational purposes only and does not constitute medical advice.