Peptide Reconstitution Calculator

How peptide reconstitution actually works

Research peptides ship as a lyophilized (freeze-dried) powder because that form is far more stable for storage and transport than a liquid solution. Before the material can be measured out in a syringe, it has to be dissolved in a diluent — almost always bacteriostatic water, a sterile saline solution preserved with 0.9% benzyl alcohol so the same vial can be safely accessed multiple times over several weeks.

Once dissolved, the vial has a fixed concentration: the total amount of peptide (in mg or IU) divided by the volume of diluent you added (in mL). That concentration is what turns a volume you can measure on a syringe into a dose you can compare across protocols.

Step-by-step reconstitution

1. Let the vial and diluent reach room temperature before mixing.
2. Draw the diluent into a syringe and inject it slowly down the inside wall of the vial — not directly onto the powder.
3. Swirl the vial gently to dissolve the powder. Do not shake it — vigorous agitation can shear and denature peptide bonds.
4. Confirm the solution is clear with no visible particulate before drawing a dose.
5. Label the vial with the reconstitution date so you can track its use-by window.

mg, mcg, IU and syringe "units" — the difference that trips people up

These four terms get used almost interchangeably in casual conversation, but they measure three different things:

• mg (milligram) / mcg (microgram) — a unit of mass. 1 mg = 1000 mcg. This is how most peptides are labelled (e.g. a "5mg vial").
• IU (International Unit) — a unit of biological potency, not mass. It's compound-specific: 1 IU of somatropin and 1 IU of HCG represent completely different masses of material, because the conversion factor is defined separately for each hormone by its WHO international standard.
• Syringe "unit" — a volume mark, equal to 1/100 mL on a standard U-100 insulin syringe. It is not a dose by itself; it only becomes one once you know the concentration of what's in the syringe. This is the step most calculation mistakes happen at.

Storage after reconstitution

Once mixed, keep the vial refrigerated at 2–8°C and protected from light. Most reconstituted research peptides remain usable for up to 28 days under those conditions, though the exact stability window depends on the specific compound — check the product page or safety data for anything unusual. Unreconstituted (lyophilized) powder is far more stable and is typically fine at 2–8°C, or even briefly at room temperature in transit, for extended periods.

Common mistakes

• Shaking instead of gently swirling the vial after adding diluent.
• Assuming "units" on the syringe directly equal "IU" of the compound without first computing the vial's actual IU/mL concentration.
• Reconstituting with regular (non-bacteriostatic) water for multi-use vials, which removes the antimicrobial protection needed for repeated access.
• Losing track of the reconstitution date and using material past its stability window.

Frequently asked questions