A retatrutide dosage calculator has to answer four questions: how many mg are in the vial, how many mL of bacteriostatic water were added, what mg amount is being measured, and what that equals on a U-100 syringe.
The core calculator formula is:
syringe units = target dose mg × BAC water mL × 100 ÷ vial mg
The supporting formulas are:
concentration = vial mg ÷ BAC water mL
mL to draw = target dose mg ÷ concentration
This page explains the math. Retatrutide is investigational and is not an FDA-approved medication as of April 28, 2026. This guide is not a recommendation to use it or a substitute for medical care.
Quick calculator setup
| Input | Example | Why it matters |
|---|---|---|
| Vial amount | 10 mg | Total retatrutide in the vial |
| BAC water added | 2 mL | Determines concentration |
| Target amount | 1 mg | Amount being measured |
| Syringe type | U-100 | 100 units = 1 mL |
Using those values:
10 mg vial ÷ 2 mL = 5 mg/mL.
1 mg ÷ 5 mg/mL = 0.2 mL.
0.2 mL × 100 = 20 units.
So a 1 mg draw from a 10 mg vial mixed with 2 mL is 20 units on a U-100 syringe.
Retatrutide calculator formulas
| Goal | Formula |
|---|---|
| Find concentration | vial mg ÷ BAC water mL |
| Convert target mg to mL | target mg ÷ concentration |
| Convert mL to U-100 units | mL × 100 |
| Direct units formula | target mg × BAC water mL × 100 ÷ vial mg |
| Doses per vial | vial mg ÷ target mg |
These formulas are the same math used by most online peptide calculators. The quality difference is whether the page clearly explains the assumptions and warnings.
Retatrutide concentration chart
| Vial size | BAC water added | Concentration | 1 mg equals | 2 mg equals | 4 mg equals |
|---|---|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 20 units | 40 units | 80 units |
| 5 mg | 2 mL | 2.5 mg/mL | 40 units | 80 units | 160 units |
| 10 mg | 1 mL | 10 mg/mL | 10 units | 20 units | 40 units |
| 10 mg | 2 mL | 5 mg/mL | 20 units | 40 units | 80 units |
| 10 mg | 4 mL | 2.5 mg/mL | 40 units | 80 units | 160 units |
| 20 mg | 2 mL | 10 mg/mL | 10 units | 20 units | 40 units |
| 20 mg | 4 mL | 5 mg/mL | 20 units | 40 units | 80 units |
| 30 mg | 3 mL | 10 mg/mL | 10 units | 20 units | 40 units |
| 30 mg | 6 mL | 5 mg/mL | 20 units | 40 units | 80 units |
Large unit numbers can exceed a 1 mL syringe. Very small unit numbers can be hard to measure accurately. Both situations are reasons to stop and clarify the setup rather than forcing the math.
Worked examples
Example 1: 10 mg vial mixed with 2 mL
10 mg ÷ 2 mL = 5 mg/mL.
At 5 mg/mL:
| Target amount | mL | U-100 units |
|---|---|---|
| 0.5 mg | 0.1 mL | 10 units |
| 1 mg | 0.2 mL | 20 units |
| 2 mg | 0.4 mL | 40 units |
| 4 mg | 0.8 mL | 80 units |
Example 2: 20 mg vial mixed with 2 mL
20 mg ÷ 2 mL = 10 mg/mL.
At 10 mg/mL:
| Target amount | mL | U-100 units |
|---|---|---|
| 0.5 mg | 0.05 mL | 5 units |
| 1 mg | 0.1 mL | 10 units |
| 2 mg | 0.2 mL | 20 units |
| 4 mg | 0.4 mL | 40 units |
Example 3: 30 mg vial mixed with 6 mL
30 mg ÷ 6 mL = 5 mg/mL.
This produces the same concentration as a 10 mg vial mixed with 2 mL. The units for each target amount are the same, but the vial contains more total doses.
Doses per vial
Doses per vial is separate from concentration. It depends on total vial mg and target mg.
| Vial amount | 0.5 mg amounts | 1 mg amounts | 2 mg amounts | 4 mg amounts |
|---|---|---|---|---|
| 5 mg | 10 | 5 | 2.5 | 1.25 |
| 10 mg | 20 | 10 | 5 | 2.5 |
| 20 mg | 40 | 20 | 10 | 5 |
| 30 mg | 60 | 30 | 15 | 7.5 |
If the result includes a half dose, that means the vial does not divide evenly at that target amount. It does not mean the leftover should automatically be used later.
How BAC water changes the calculator result
Adding more bacteriostatic water does not add more retatrutide. It spreads the same total mg across more volume.
| Setup | Concentration | Practical result |
|---|---|---|
| Less water | Higher mg/mL | Fewer syringe units per mg |
| More water | Lower mg/mL | More syringe units per mg |
| Same vial mg, different water | Different concentration | Different unit marks for the same mg amount |
Lower concentration can make small amounts easier to measure. Higher concentration can reduce injection volume. The tradeoff is precision versus volume, and it should be decided before mixing.
For the detailed mixing workflow, see how to reconstitute retatrutide. For broader context, use the retatrutide guide and retatrutide dosage guide.
Retatrutide is not the same as semaglutide or tirzepatide
Retatrutide is often discussed beside semaglutide and tirzepatide because all three affect incretin-related pathways, but the receptor profile is different. Retatrutide is being studied as a triple agonist: GLP-1, GIP, and glucagon receptor activity.
That matters because dose numbers across these compounds are not interchangeable. A semaglutide chart cannot be used for retatrutide. A tirzepatide unit chart cannot be used for retatrutide. The vial math may look similar, but the drug, evidence base, tolerability, and regulatory status are different.
Safety and legal context
Retatrutide remains investigational. There is no FDA-approved commercial retatrutide product, no approved retail brand, and no standard prescription label equivalent to Ozempic, Wegovy, Mounjaro, or Zepbound. Research-market products may vary in purity, identity, sterility, storage history, and labeling accuracy.
Calculator math cannot solve those quality-control issues. It can only explain volume conversion after the vial amount and water volume are known.
Seek medical care urgently for severe abdominal pain, persistent vomiting, dehydration symptoms, allergic reaction symptoms, chest pain, fainting, or severe weakness. Do not continue escalating or repeating use after a severe reaction.
Calculator checklist before using a number
| Question | Do not proceed unless the answer is clear |
|---|---|
| What is the compound? | Retatrutide, not another GLP/GIP medication |
| How many mg are in the vial? | Total amount before mixing |
| How many mL were added? | Actual water volume used |
| What syringe type? | This page assumes U-100 |
| What amount is being measured? | Target amount in mg |
| Was the vial stored correctly? | Temperature and sterility matter |
FAQ
How do you calculate retatrutide units?
Use target dose mg × BAC water mL × 100 ÷ vial mg. For example, 1 mg from a 10 mg vial mixed with 2 mL equals 1 × 2 × 100 ÷ 10 = 20 units.
How much BAC water should you add to retatrutide?
There is no universal answer. The water volume determines concentration and syringe units. More water means more units per mg; less water means fewer units per mg. Use clinician, protocol, or pharmacy guidance rather than guessing.
What is the concentration of a 10 mg vial mixed with 2 mL?
10 mg ÷ 2 mL = 5 mg/mL.
How many units is 1 mg of retatrutide?
It depends on concentration. At 5 mg/mL, 1 mg is 20 units. At 10 mg/mL, 1 mg is 10 units. At 2.5 mg/mL, 1 mg is 40 units.
Is retatrutide approved?
No. As of April 28, 2026, retatrutide is investigational and not FDA-approved.
Bottom line
A retatrutide dosage calculator is concentration math: vial mg, BAC water mL, target mg, and U-100 syringe units. The direct formula is target mg × BAC water mL × 100 ÷ vial mg. Use the math to understand labels and examples, not to replace medical guidance or quality-control checks.
