How do I calculate peptide reconstitution units?

Divide your vial size in milligrams by the amount of bacteriostatic water in milliliters to get the concentration. Then divide your desired dose in micrograms by the concentration to get the volume in milliliters. Multiply by 100 to convert to insulin syringe units (on a standard U-100 syringe, 1 mL = 100 units).

How much bacteriostatic water should I add to a peptide vial?

Common amounts are 1 mL or 2 mL of bacteriostatic water. Using more water makes it easier to measure small doses accurately, while using less water means fewer injections per vial. A 5 mg vial reconstituted with 2 mL of BAC water gives a concentration of 2,500 mcg per mL.

What is a unit on an insulin syringe?

On a standard U-100 insulin syringe, 100 units equals 1 mL. Each small tick mark on a 1 mL syringe represents 1 unit (0.01 mL). On a 0.5 mL syringe, each tick mark also represents 1 unit, but the syringe only goes up to 50 units.

How many units is 250 mcg of BPC-157?

It depends on how much bacteriostatic water you added. With a 5 mg vial and 2 mL of BAC water, the concentration is 2,500 mcg/mL (25 mcg per unit). To get a 250 mcg dose, draw 10 units on a U-100 insulin syringe. With 1 mL of BAC water, draw 5 units.

Can I use sterile water instead of bacteriostatic water for peptides?

Sterile water can be used but lacks the 0.9% benzyl alcohol preservative found in bacteriostatic water. Without the preservative, the reconstituted peptide must be used within 24 hours and cannot be stored for multiple doses. Bacteriostatic water allows the vial to last up to 28 days when refrigerated.

How long does a reconstituted peptide vial last?

When reconstituted with bacteriostatic water and stored refrigerated at 2-8°C (36-46°F), most peptide vials last up to 28 days. If reconstituted with sterile water (no preservative), the vial should be used within 24 hours. Never freeze a reconstituted peptide solution.

How much bacteriostatic water for a 5 mg peptide vial?

The most common amounts are 1 mL or 2 mL. Using 2 mL gives a concentration of 2,500 mcg/mL, making it easier to measure small doses precisely. Using 1 mL gives 5,000 mcg/mL, meaning fewer injections per vial but smaller volumes that are harder to measure accurately.

Peptide Reconstitution Calculator — How many units to inject

How the math works

Reconstitution math is straightforward once you know the formula. The calculator above handles it for you, but here's what's happening behind the scenes:

concentration = vial mg × 1,000 ÷ water mL

volume = desired mcg ÷ concentration

syringe units = volume × 100

Step 1. Convert your vial from milligrams to micrograms (multiply by 1,000), then divide by the amount of bacteriostatic water you added. This gives you the concentration in mcg per mL.

Step 2. Divide your desired dose (in mcg) by the concentration. This gives you the volume to inject in milliliters.

Step 3. On a standard U-100 insulin syringe, 1 mL equals 100 units. Multiply your volume by 100 to get the number of units (tick marks) to draw.

Tips for accuracy

Use more water for small doses. If your calculated dose is under 5 units, it's hard to measure precisely. Add more BAC water to increase the volume per dose — accuracy matters more than concentration.
Inject the water slowly. When reconstituting, aim the stream along the glass wall, not directly onto the powder. Let it dissolve gently — never shake the vial.
Account for dead space. Insulin syringes retain a small amount of liquid in the needle hub (about 0.5-1 unit). For very small doses, this matters.
Double-check your syringe type. This calculator assumes a standard U-100 insulin syringe (100 units = 1 mL). If you're using a different syringe, the unit markings will differ.

For a complete walkthrough of the reconstitution process including equipment, sterile technique, and storage, see our full reconstitution guide. Once reconstituted, proper storage is critical — our peptide storage and handling guide covers temperature, light exposure, and shelf life. If you're new to peptides entirely, start with our beginner's guide.

Worked examples for common peptides

These are the most frequently reconstituted peptides. Each example uses standard vial sizes and common bacteriostatic water volumes so you can follow along with the calculator above.

BPC-157 — 250 mcg dose

A BPC-157 vial is typically 5 mg. Add 2 mL of bacteriostatic water. That gives you a concentration of 2,500 mcg/mL, or 25 mcg per unit. For a standard 250 mcg dose, draw 10 units on your insulin syringe. The vial will last 20 doses.

TB-500 — 2.5 mg dose

TB-500 is commonly dosed higher than most peptides. With a 5 mg vial and 2 mL of BAC water, the concentration is 2,500 mcg/mL (25 mcg per unit). For a 2,500 mcg (2.5 mg) loading dose, draw 50 units — exactly half the syringe. That's 2 doses per vial. Many people use TB-500 alongside BPC-157 for injury recovery.

CJC-1295 / Ipamorelin — 100 mcg dose

CJC-1295 and ipamorelin are often stacked for growth hormone release. CJC-1295 typically comes in 2 mg vials — add 2 mL of BAC water for a concentration of 1,000 mcg/mL (10 mcg per unit). For 100 mcg, draw 10 units. Ipamorelin comes in 5 mg vials — with 2 mL of BAC water that's 2,500 mcg/mL (25 mcg per unit). For 100 mcg, draw 4 units.

GHK-Cu — 500 mcg dose

GHK-Cu vials are typically 10 mg. Add 2 mL of BAC water for a concentration of 5,000 mcg/mL (50 mcg per unit). For a 500 mcg dose, draw 10 units. The vial will last 20 doses. GHK-Cu is also being studied for hair loss.

Semaglutide — 250 mcg dose

Compounded semaglutide (the peptide behind GLP-1 weight loss drugs) commonly comes in 5 mg vials. With 2 mL of BAC water, the concentration is 2,500 mcg/mL (25 mcg per unit). For a 250 mcg starting dose, draw 10 units. The vial provides 20 doses at this level.

Quick reference table

Common peptides at standard reconstitution volumes with typical doses. All values assume a U-100 insulin syringe.

Peptide	Vial	BAC Water	Dose	Draw
BPC-157	5 mg	2 mL	250 mcg	10 units
BPC-157	5 mg	2 mL	500 mcg	20 units
TB-500	5 mg	2 mL	750 mcg	15 units
TB-500	5 mg	2 mL	2,500 mcg	50 units
CJC-1295	2 mg	2 mL	100 mcg	10 units
Ipamorelin	5 mg	2 mL	100 mcg	4 units
Ipamorelin	5 mg	2 mL	200 mcg	8 units
GHK-Cu	10 mg	2 mL	100 mcg	2 units
GHK-Cu	10 mg	2 mL	500 mcg	10 units
Epithalon	10 mg	3 mL	300 mcg	9 units
Semaglutide	5 mg	2 mL	250 mcg	10 units
Sermorelin	2 mg	2 mL	200 mcg	20 units
AOD-9604	5 mg	2 mL	300 mcg	6 units
Selank	5 mg	2 mL	300 mcg	6 units
Semax	5 mg	2 mL	600 mcg	12 units
KPV	5 mg	2 mL	500 mcg	10 units
Thymosin Alpha-1	5 mg	2 mL	750 mcg	15 units
PT-141	2 mg	1 mL	500 mcg	25 units
DSIP	5 mg	2 mL	100 mcg	2 units

Peptide Reconstitution Calculator