Retatrutide dosing calculator

Educational reference only

Retatrutide is a prescription medication in most countries. This page is for educational reference only. Underground Biohacking does not provide dosing protocols, interaction warnings, or usage guidance for prescription compounds. If you are using or considering Retatrutide, work with a licensed clinician.

CompoundRetatrutide

Vial

Water

Your dose

1 mg = 1000 mcg.

Your syringe

Draw this much

Enter a vial size, water volume and dose to see where to pull.

0 units0.3 mL barrel, U-100 scale30 units

For tracking and calculation purposes only. Not medical advice. Based on a standard U-100 insulin syringe.

No label schedule

Retatrutide is investigational and not approved, so no label schedule exists.

Retatrutide is investigational and not approved, so there is no label and no week-by-week schedule. The one source is the phase 2 trial, which ran 1, 4, 8 or 12 mg once weekly for 48 weeks, started at 2 or 4 mg, and stepped up every 4 weeks for up to 12 weeks.

Source: Jastreboff et al., NEJM 2023;389:514-526

How the units are worked out

Your vial holds a fixed amount of peptide. The water you add sets the concentration (how much peptide sits in each millilitre). The concentration then decides how much liquid carries your dose.

Three steps, in order:

Concentration (mcg/mL) = peptide in the vial (mcg) divided by water added (mL).
Volume (mL) = your dose (mcg) divided by the concentration (mcg/mL).
Units to draw = volume (mL) multiplied by 100.

That last step is the syringe, not the peptide. A U-100 insulin syringe is marked so 100 units hold 1 mL, so 0.1 mL reads as 10 units.

A worked example

Enter your dose in the calculator above and this line shows the numbers worked through.

Water and units at a glance

Retatrutide at different mixes. Every row opens the calculator on that mix.

Vial	Water	Concentration
10 mg	1 mL	10,000 mcg/mL
10 mg	2 mL	5,000 mcg/mL
10 mg	3 mL	3,333 mcg/mL
10 mg	5 mL	2,000 mcg/mL

Units appear once you enter a dose.

Pre-filled numbers are the most-used setups reported by users of public calculators (WPA dosing data, Aug 2026). Not a recommendation.

Mixing and storage

Run the water down the inside wall of the vial and let the powder dissolve on its own. Never shake it. Label the vial with the compound, the total mass, the water you added, the concentration and the date. A sealed freeze-dried vial keeps 12 to 24 months in the fridge at 2 to 8°C. Once mixed with preserved water, such as bacteriostatic water, that drops to roughly 28 days refrigerated. Keep it at the back of the fridge, away from light and away from the door's temperature swings.

Other compounds

Questions

Is retatrutide approved by the FDA?

No. Retatrutide has no approval from the FDA or any other regulator, and it is not approved in any country. It sits in phase 3 testing, which is the last stage before a company can apply for approval. Nothing about that stage makes it available. The FDA drug approval database holds no record for it. Any product sold to the public under this name is outside the regulated system entirely.

What did the trials actually show?

Two phase 2 trials carry most of the evidence. In adults with obesity, 48 weeks of treatment produced substantial weight loss. In adults with type 2 diabetes, blood sugar control improved and weight fell. A substudy in people with fatty liver disease showed liver fat dropping alongside weight and belly fat. A kidney analysis found a urine marker of kidney strain falling. All of this is phase 2 work, not phase 3.

How is it different from semaglutide and tirzepatide?

It hits one more target. Semaglutide, approved as Ozempic and Wegovy, acts on the GLP-1 receptor. Tirzepatide acts on GLP-1 and GIP. Retatrutide acts on GLP-1, GIP and glucagon. In a pooled comparison across trials, it produced more weight loss than the GLP-1 only drugs. It also came with a higher rate of side effects. The two approved drugs have far longer safety records behind them.

What are the known risks?

Gut problems are the most common issue reported, and allergic type reactions came up more often than with placebo. Heart rate went up during treatment, more so at higher amounts, then settled after about six months. Pooled trial data shows a higher overall side effect rate than for drugs with fewer targets. In the phase 2 diabetes trial no one had severe low blood sugar and no one died.

Is it safe over the long term?

Nobody knows. The published human trials ran for months, not years, and they enrolled a few hundred people each. That is enough to spot common side effects and far too little to spot rare or slow ones. Phase 3 trials exist partly to answer this question, and their results are not out. Anyone claiming a long term safety record for retatrutide is describing evidence that has not been published.

What should I ask a doctor about it?

Ask what your actual goal is, then what approved treatments already meet it. Approved options for weight and blood sugar have published long term data and a licensed supply chain, and retatrutide has neither. If the trial results interest you, ask whether you might qualify for a registered clinical trial near you. Ask what monitoring any approved treatment would need. That is a conversation your doctor can act on.