What a Peptide Calculator Actually Does
Research peptides ship as a dried powder inside a sealed vial. Before anything can be measured, that powder has to be dissolved in bacteriostatic water — a step called reconstitution. The problem is that the vial doesn't come with a "one syringe unit equals this much peptide" label, because that number depends entirely on how much water you add. Add a little water and the solution is concentrated; add more and it's dilute. Your syringe reads volume, not milligrams, so the whole job is turning "I want this dose" into "draw to this line."
That conversion is where mistakes happen. This calculator removes the arithmetic: you enter the vial's total milligrams, the dose you're targeting, and your syringe size, and it does the concentration math for you and shows the exact fill line on the syringe.
How to Reconstitute a Peptide, Step by Step
The calculator handles the numbers, but the physical process matters just as much. A typical reconstitution looks like this:
- Let everything reach room temperature. Take the peptide vial and the bacteriostatic water out of the fridge and give them 15–20 minutes. Adding cold water to cold powder can stress the peptide.
- Sanitize the stoppers. Wipe the rubber top of both the peptide vial and the water vial with an alcohol swab and let them air dry.
- Draw your bacteriostatic water. Pull the amount of water the calculator recommends into a syringe.
- Add the water slowly, down the side of the glass. Insert the needle at an angle and let the water run down the inside wall of the vial rather than blasting it directly onto the powder. This protects the peptide.
- Swirl — never shake. Gently roll or swirl the vial until the solution is completely clear. Shaking can damage delicate peptide chains and create foam.
- Inspect. A properly reconstituted vial is clear with no floating particles. If it's cloudy or has debris, don't use it.
- Store it cold. Keep the reconstituted vial refrigerated, and use it within the window recommended for that peptide (commonly around 28–30 days).
Once the vial is mixed, the calculator's "draw to X units" number tells you exactly how far to pull the plunger for each dose.
Understanding the Numbers
Three ideas do all the work, and once they click, reconstitution stops being intimidating:
Concentration is how much peptide is packed into each milliliter of solution. It's the vial's total milligrams divided by the milliliters of water you added. A 10 mg vial mixed with 1 mL of water is 10 mg/mL; the same vial in 2 mL is 5 mg/mL. More water always means a lower concentration.
Draw volume is how much liquid contains your dose. It's your dose divided by the concentration. At 10 mg/mL, a 2 mg dose lives in 0.2 mL of solution.
Units are just the markings on an insulin syringe. On a standard U-100 syringe, 100 units equal 1 mL, so that 0.2 mL dose is drawn to the 20-unit line. This is the number you actually use at injection time, and it's what the calculator highlights on the syringe visual.
Peptides and Blends You Can Calculate
The calculator supports single peptides and multi-peptide blends across several categories:
- GLP-1 and metabolic compounds — Retatrutide, Semaglutide, Tirzepatide, Cagrilintide. Higher-dose compounds where getting the units right matters most.
- Healing and recovery peptides — BPC-157, TB-500, GHK-Cu, KPV, and blends like GLOW, KLOW, and Wolverine.
- Growth-hormone secretagogues — CJC-1295, Ipamorelin, the CJC-1295 + Ipamorelin blend, Tesamorelin, and HGH.
- Other research peptides — Melanotan I, Melanotan II, PT-141.
For blends, the calculator treats the vial's combined milligrams as one number and shows the reconstitution and draw for the whole blend, so you don't have to solve each component separately.
Why Bacteriostatic Water
Reconstitution uses bacteriostatic water specifically — sterile water with a small amount of benzyl alcohol that inhibits bacterial growth. That preservative is what lets a reconstituted vial be stored and drawn from over multiple days rather than being a single-use solution. It's the standard diluent for multi-dose peptide vials, and it's what the calculator's water amounts assume.
More Reconstitution & Dosing Guides
For deeper, per-compound references, see our full guides library, including how to reconstitute peptides step by step and the BPC-157 dosage calculator guide.
Frequently Asked Questions
- How much bacteriostatic water should I add to my peptide?
- There's no single right answer — it depends on the vial size and how readable you want your draw to be. Less water gives a more concentrated solution and a smaller draw; more water gives a larger, easier-to-read draw. This calculator uses a recommended amount for common peptides that keeps the concentration practical, and you can override it in Manual mode to match your own preference.
- What syringe do I need for peptides?
- Most people use a standard U-100 insulin syringe, typically 29–31 gauge, in a half-inch length for subcutaneous injections. The calculator shows your dose as units on that U-100 scale.
- How do I read units on an insulin syringe?
- On a U-100 syringe, the barrel is marked from 0 to 100 units, where 100 units equal 1 milliliter. If the calculator says draw to 40 units, you pull the plunger to the 40 mark. Ten units is 0.1 mL, fifty units is 0.5 mL, and so on.
- Can I use this calculator for peptide blends?
- Yes. For blends like GLOW, KLOW, or CJC-1295 + Ipamorelin, the calculator uses the vial's total combined milligrams and shows a single reconstitution and draw for the whole blend.
- Do I need to refrigerate reconstituted peptides?
- Reconstituted vials are generally stored in the refrigerator and used within the window recommended for that peptide. Bacteriostatic water's preservative is what allows multi-day storage after mixing.
- Is this calculator free?
- Yes — it's completely free, requires no account, and works instantly. It's a tool for doing reconstitution and dosing math, not a substitute for guidance from a qualified professional.