How much bacteriostatic water do I add to a 50 mg retatrutide vial?

There is no single right amount. More water makes each draw bigger and easier to measure; less water keeps the volume small. With 10 mL, a 50 mg vial is 5 mg/mL, so every 10 units on a U-100 insulin syringe holds 500 mcg. With 2 mL it is 25 mg/mL (2.5 mg per 10 units). With 3 mL it is 16.67 mg/mL (1.667 mg per 10 units). With 5 mL it is 10 mg/mL (1 mg per 10 units).

How many units is 2 mg of retatrutide from a 50 mg vial?

With 10 mL of water the vial is 5 mg/mL, so 2 mg is 0.4 mL, or 40 units on a U-100 syringe. With a different water volume the units change but the amount does not. The amount is an example for the math, not a recommendation.

How many 2 mg draws are in a 50 mg retatrutide vial?

25 (50 mg ÷ 2 mg), whatever volume of water you add. In practice a little is lost to the syringe dead space and the last drops in the vial.

Retatrutide 50 mg Reconstitution: BAC Water & Units

Short answer: 10 mL of bacteriostatic water in a 50 mg retatrutide vial makes 5 mg/mL. On a U-100 insulin syringe (1 mL = 100 units), every 10 units then holds 500 mcg. More water gives a weaker solution and a bigger draw for the same amount; the amount in the vial stays 50 mg.

Water volume chart for a 50 mg vial

50 mg retatrutide vial, U-100 insulin syringe.
Water added	Concentration	Per 10 units	Per 1 unit
2 mL	25 mg/mL	2.5 mg	250 mcg
3 mL	16.67 mg/mL	1.667 mg	166.667 mcg
5 mL	10 mg/mL	1 mg	100 mcg
10 mL	5 mg/mL	500 mcg	50 mcg

Syringe units by amount

The amounts below are examples to show the conversion, not doses. How much to take is a decision for you and your prescriber.

Units on a U-100 syringe from a 50 mg vial.
Water added	1 mg	2 mg	4 mg
2 mL	4 units	8 units	16 units
3 mL	6 units	12 units	24 units
5 mL	10 units	20 units	40 units
10 mL	20 units	40 units	80 units

A 50 mg vial holds 50 draws of 1 mg, 25 draws of 2 mg, 12.5 draws of 4 mg, no matter how much water you add.

How far a 50 mg vial goes

Draws per vial depend only on the amount per draw, not on the water. The volume and units columns use 10 mL of water (5 mg/mL). Example amounts only, not doses.

50 mg vial: draws, volume and units per example amount.
Amount per draw	Draws per vial	Volume per draw	Units per draw
500 mcg	100	0.1 mL	10 units
1 mg	50	0.2 mL	20 units
2 mg	25	0.4 mL	40 units
4 mg	12.5	0.8 mL	80 units
8 mg	6.3	1.6 mL	over 1 mL

Real counts run a little lower: some liquid stays in the syringe and at the bottom of the vial.

50 mg next to other retatrutide vial sizes

To get the same 5 mg/mL from another vial size, scale the water with the vial. Same strength means the same units for the same amount, whichever vial it comes from.

Water for 5 mg/mL, and 2 mg draws per vial, by vial size.
Vial	Water for 5 mg/mL	2 mg draws per vial
5 mg	1 mL	2.5
10 mg	2 mL	5
15 mg	3 mL	7.5
20 mg	4 mL	10
30 mg	6 mL	15
40 mg	8 mL	20
50 mg (this page)	10 mL	25
60 mg	12 mL (over 10 mL)	30

The math

Concentration. 50 mg ÷ 10 mL = 5 mg/mL
Volume to draw. amount ÷ 5 mg/mL = mL
Syringe units. mL × 100 = units

For a different water volume or amount, the free peptide reconstitution calculator works backwards from the amount you want and suggests a water volume that lands on a clean syringe mark.

Other retatrutide vial sizes: Retatrutide 5 mg · Retatrutide 10 mg · Retatrutide 15 mg · Retatrutide 20 mg · Retatrutide 30 mg · Retatrutide 40 mg · Retatrutide 60 mg

Half-life, time to peak and sources are on the main Retatrutide guide.

Retatrutide 50 mg reconstitution: how much water and how many units