Research reference — not human dosing guidance
Retatrutide Dosage Chart (Units, mg/mL and Half-Life)
This page converts a retatrutide research vial into the numbers a laboratory actually works with: the concentration produced by a given volume of bacteriostatic water, and the exact marks to draw on a U-100 insulin syringe. Retatrutide (LY3437943) is an investigational triple agonist supplied for in vitro research only — the tables below are arithmetic, not a protocol for use in humans or animals.
Retatrutide concentration chart by vial size
Every vial size we stock, the bacteriostatic water volume most laboratories choose for it, and the concentration that results. The final column is the shortcut: how many U-100 units correspond to 1 mg at that concentration.
| Vial size | Bacteriostatic water | Concentration | Per mL | Units for 1 mg |
|---|---|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL | 2,500 mcg/mL | 40 units |
| 10 mg | 2 mL | 5 mg/mL | 5,000 mcg/mL | 20 units |
| 15 mg | 3 mL | 5 mg/mL | 5,000 mcg/mL | 20 units |
| 30 mg | 3 mL | 10 mg/mL | 10,000 mcg/mL | 10 units |
| 40 mg | 4 mL | 10 mg/mL | 10,000 mcg/mL | 10 units |
| 60 mg | 3 mL | 20 mg/mL | 20,000 mcg/mL | 5 units |
| 80 mg | 4 mL | 20 mg/mL | 20,000 mcg/mL | 5 units |
| 100 mg | 5 mL | 20 mg/mL | 20,000 mcg/mL | 5 units |
A U-100 insulin syringe is graduated so that 100 units equals 1 mL. Units are therefore simply the volume in mL multiplied by one hundred — there is no peptide-specific conversion involved.
Units to draw for a given amount
Read down the column for your concentration and across from the amount of peptide the study calls for.
| Amount | 2.5 mg/mL | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|---|
| 250 mcg | 10 units | 5 units | 2.5 units | 1.25 units |
| 500 mcg | 20 units | 10 units | 5 units | 2.5 units |
| 1 mg | 40 units | 20 units | 10 units | 5 units |
| 1.5 mg | 60 units | 30 units | 15 units | 7.5 units |
| 2 mg | 80 units | 40 units | 20 units | 10 units |
| 3 mg | 120 units * | 60 units | 30 units | 15 units |
* Over 100 units exceeds 1 mL, which is more than a standard 1.0 mL U-100 syringe holds. Reconstitute at a higher concentration instead of splitting the draw.
The arithmetic behind the chart
There are only two calculations, and both are simple division.
Concentration
vial mass (mg) ÷ water volume (mL) = mg/mL. A 10mg vial with 2 mL of bacteriostatic water is 5 mg/mL, which is 5,000 mcg/mL.
Units to draw
amount (mg) ÷ concentration (mg/mL) × 100 = units. For 500 mcg at 5 mg/mL: 0.5 ÷ 5 = 0.1 mL, which is 10 units.
Worked example
A laboratory holds a 30mg retatrutide vial and reconstitutes it with 3 mL of bacteriostatic water. The concentration is 30 ÷ 3 = 10 mg/mL, or 10,000 mcg/mL. A 250 mcg draw is 0.25 ÷ 10 = 0.025 mL, which is 2.5 units on a U-100 syringe. A 2 mg draw is 0.2 mL, or 20 units. The vial contains 30 mg in total, so it supports 120 separate 250 mcg draws or 15 separate 2 mg draws.
More water does not mean less peptide
This is the single most common misreading of a dosage chart. The vial contains a fixed mass of lyophilised peptide. Bacteriostatic water is a solvent, not an ingredient — it changes how spread out that mass is, and nothing else. A 10mg vial reconstituted with 1 mL is 10 mg/mL, and 1 mg is 10 units. The same vial reconstituted with 4 mL is 2.5 mg/mL, and the same 1 mg is now 40 units. Both draws contain identical material.
Practically, more dilute solutions are easier to measure precisely, because small amounts land on readable syringe marks instead of a sliver near the tip. More concentrated solutions keep the total draw volume small. Laboratories generally pick the volume that puts their typical draw somewhere between 5 and 50 units.
Retatrutide half-life in context
Half-life figures below come from published pharmacokinetic literature and are provided as research background only.
| Compound | Reported half-life | Notes |
|---|---|---|
| Retatrutide (LY3437943) | ≈ 6 days (about 130–160 hours) | Reported in published phase 1 pharmacokinetic data; supports once-weekly study intervals in the literature. |
| Tirzepatide (LY3298176) | ≈ 5 days (about 120 hours) | Fatty-acid acylation and albumin binding slow clearance in the same way. |
| Semaglutide | ≈ 7 days (about 165 hours) | Included for context only; single GLP-1 receptor agonist. |
| Native GLP-1 | ≈ 2 minutes | Rapid DPP-4 degradation — the problem the acylated analogs were designed around. |
Common measurement mistakes
- Confusing units with millilitres. Ten units is 0.1 mL, not 10 mL. The unit scale is the one printed on a U-100 syringe.
- Confusing mcg with mg. 250 mcg is 0.25 mg. A thousandfold arithmetic error is the easiest one to make on this page.
- Reusing an old chart after changing water volume. Every unit figure is tied to one concentration. Change the water and the whole column changes.
- Assuming all syringes are U-100. U-40 syringes exist and their marks mean something different. Check the barrel.
- Not recording the reconstitution date. Concentration is meaningless in a record without the date and batch it applies to.
Retatrutide research vials
Eight vial sizes from 5mg to 100mg, each verified to ≥99.8% HPLC purity with a batch-specific Certificate of Analysis.
Retatrutide dosage chart FAQ
How do you read a retatrutide dosage chart?
Find the vial size you have, read across to the bacteriostatic water volume, and the chart gives the resulting concentration in mg/mL and mcg/mL. The units column converts a given amount of peptide into marks on a U-100 insulin syringe, where 100 units equals 1 mL.
How many units is 1mg of retatrutide on an insulin syringe?
It depends on concentration. A 10mg vial reconstituted with 2 mL is 5 mg/mL, so 1 mg is 0.2 mL — 20 units on a U-100 syringe. At 10 mg/mL the same 1 mg is 10 units; at 20 mg/mL it is 5 units.
How much bacteriostatic water should be added to a 10mg retatrutide vial?
2 mL is the most common laboratory choice because it produces a round 5 mg/mL (5,000 mcg/mL) concentration and easy 5-unit increments. Larger vials are typically reconstituted with 3–5 mL to keep the solution volume workable.
Does adding more bacteriostatic water reduce the amount of retatrutide?
No. The vial always contains the same total mass of peptide. More water lowers the concentration, so the same amount of material is drawn at a larger volume and a higher unit mark on the syringe.
What is the half-life of retatrutide?
Published phase 1 pharmacokinetic data report a terminal half-life of roughly six days, in the region of 130–160 hours. That long half-life comes from fatty-acid acylation and albumin binding, and it is why published study designs use weekly intervals.
Is this chart a human dosing protocol?
No. It is arithmetic for preparing and measuring research material in a laboratory setting. Retatrutide is an investigational compound supplied strictly for in vitro research and is not for human or veterinary use.
More retatrutide research resources
All products and information on this page are supplied strictly for in vitro laboratory research by qualified professionals. Retatrutide is an investigational compound and is not approved by the FDA for human or veterinary use. The figures here are reconstitution arithmetic, not dosing guidance — we do not provide therapeutic recommendations.