Free tool
Peptide reconstitution calculator
Concentration equals vial mass divided by diluent volume. Tell it what is in the vial and how much liquid you are adding, and it does the arithmetic — or switch it round and it tells you the volume to add for the strength you want.
How much liquid are you adding?
Drag the slider, or switch it round and let the calculator work out the volume for a strength you want.
Your answer
One number, in plain words. The rest is there if you want it.
Show the other figures
- In micrograms
- 5,000 µg/mL
- Total in the vial
- 10.0 mg
- In every 0.1 mL
- 500 µg
- Per unit, 100-unit syringe
- 50 µg
Arithmetic only. This tool converts between mass, volume and concentration for laboratory preparation and dilution planning. It is not dosing guidance, and nothing here is a therapeutic claim. All materials are supplied for in-vitro laboratory research use only. Diluting a solution you have already made? Use the serial dilution calculator; to find the volume holding a given mass, use the volume converter.
How the arithmetic works
concentration (mg/mL) = vial mass (mg) ÷ diluent volume (mL)
Choosing the diluent volume is choosing the concentration, and it cannot be undone once the powder is dissolved. Decide the smallest volume you will need to measure accurately, then pick a concentration where that volume sits comfortably within your pipette or syringe range — measuring 0.02 mL accurately is harder than measuring 0.2 mL. The full method, including serial dilution with C₁V₁ = C₂V₂, is in the reconstitution and dilution guide.
Before you reconstitute
- Bring the sealed vial to room temperature first, so warm air does not condense moisture onto cold powder.
- Direct the diluent down the inside wall of the vial. Do not inject it straight onto the cake, and do not shake or vortex — swirl gently until dissolved.
- Check the certificate of analysis for peptide content. The label mass is powder, not peptide — see how to read a COA.
- Aliquot if the vial will be entered repeatedly, and store the solution at 2–8 °C.
Bacteriostatic water is stocked in 3 mL and 10 mL vials. What it is and how it differs from sterile water is covered in its own guide.
Frequently asked
How do I calculate peptide concentration?
Concentration equals vial mass divided by diluent volume. A 10 mg vial reconstituted with 2 mL of bacteriostatic water gives 5 mg/mL. The lyophilised powder contributes negligible volume, so nothing else affects the result.
How much bacteriostatic water should I add?
Whatever volume gives the concentration your protocol needs, since volume determines concentration and cannot be changed afterwards. Switch the calculator to set the strength instead, and it returns the volume required.
What is the difference between mg/mL and µg/mL?
A factor of one thousand. 1 mg/mL equals 1000 µg/mL. Most laboratory work is easier to plan in µg/mL, which is why both are shown.
Does the label mass equal the peptide mass?
No. A lyophilised vial contains peptide plus residual water plus counter-ions, typically trifluoroacetate or acetate. Where the certificate of analysis states a peptide content of, say, 82%, a 10 mg vial holds roughly 8.2 mg of peptide. Calculate from the COA figure where peptide mass matters.