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Calculator

Peptide Reconstitution Calculator

Convert any vial-size and bacteriostatic-water volume into a precise mcg/mL concentration and the corresponding U-100 / U-50 syringe ticks for the dose you need.

Reconstitution inputs

mg

Total peptide mass in the vial.

mL

Typical research volume: 1 – 3 mL.

mcg

Use the dosage calculator to derive this from bodyweight.

Results

Concentration

2500 mcg/mL

Draw volume

0.100 mL

U-100 syringe ticks

10.0

U-50 syringe ticks

10.0

Quick conversion table (at this concentration)

DoseVolumeU-100 ticks
100 mcg0.040 mL4.0
200 mcg0.080 mL8.0
250 mcg0.100 mL10.0
500 mcg0.200 mL20.0
1000 mcg0.400 mL40.0
2000 mcg0.800 mL80.0

The reconstitution arithmetic

Lyophilised research peptides arrive as a freeze-dried powder in a sealed vial. Before any laboratory administration can occur, the powder is dissolved in bacteriostatic water — a sterile water containing 0.9% benzyl alcohol that suppresses microbial growth across multiple punctures of the rubber stopper. The resulting concentration drives every downstream dose calculation.

Concentration (mcg/mL) = vial mass (mg) × 1000 ÷ BAC water volume (mL). For example, a 5 mg vial reconstituted with 2 mL of bacteriostatic water yields a concentration of 2,500 mcg/mL, so a 250 mcg research dose corresponds to 0.10 mL — 10 ticks on a U-100 insulin syringe.

Best-practice notes

  • Inject the bacteriostatic water slowly down the inside wall of the vial; never flush the powder.
  • Gently swirl, do not shake — agitation can denature larger peptides.
  • Store reconstituted vials refrigerated; most research peptides remain stable for 14 – 28 days.
  • Allow vials to come to room temperature before withdrawing to reduce flash-evaporation losses.

Supporting research

  • Toth EL et al., Stability of reconstituted peptide hormones in bacteriostatic water, J Pharm Sci, 2009.
  • USP <797> standards on multi-dose vial integrity post-reconstitution.
  • Guidance from manufacturer monographs on commonly investigated GHRH and incretin analogs.

Related tools

Frequently asked questions

How much bacteriostatic water should I use to reconstitute a 5 mg peptide vial?
The typical research range is 1–3 mL of bacteriostatic water per 5 mg vial. Reconstituting at 2 mL produces a clean 2,500 mcg/mL concentration where common research doses (250 mcg, 500 mcg) land on round syringe-tick numbers.
Can I use sterile water instead of bacteriostatic water?
Sterile water works for single-use reconstitution that will be administered within a few hours. Bacteriostatic water contains 0.9% benzyl alcohol that suppresses microbial growth across multiple stopper punctures, extending usable life to 14–28 days under refrigeration.
How long does a reconstituted peptide vial last?
Most reconstituted research peptides remain stable for 14–28 days when stored refrigerated at 2–8 °C. GLP-1 class peptides (semaglutide, tirzepatide) and BPC-157 sit at the longer end; small fragile peptides at the shorter end.
Why does the calculator show different ticks for U-100 and U-50 syringes?
Both syringes use the same scale (1 tick = 0.01 mL), so the tick count for a given volume is identical. The U-50 simply tops out at 50 ticks (0.5 mL) — useful for higher-precision micro-doses.
Should I shake the vial when dissolving the powder?
No. Aim the bacteriostatic water at the inside wall of the vial and let it run down onto the powder, then swirl gently. Shaking can shear longer peptide chains and create foam that traps active material.