Peptide calculator: reconstitution, concentration and draw volume
Enter the peptide mass in the vial, the volume of diluent you add, and the quantity you want per draw. The calculator returns the concentration, the volume to draw, the matching syringe graduation and how many draws the vial holds. For laboratory research use only.
arithmetic for laboratory preparation of lyophilised peptides. It is not medical,
veterinary or dosing guidance, and nothing here is intended for human or animal
administration. Verify every calculation against your own records and your
certificate of analysis before use.
Reverse: how much diluent for a target concentration?
If the experiment specifies a concentration rather than a quantity per draw, work backwards: enter the peptide mass and the concentration you want, and the calculator returns the diluent volume to add.
How to use the peptide calculator
- Peptide in vial — the mass printed on the vial label, in mg or mcg. For the most accurate result, use the net peptide content from the lot’s certificate of analysis rather than the gross fill weight.
- Diluent added — the volume of bacteriostatic or sterile water you add to the vial, in mL.
- Quantity per draw — the amount of peptide you want in each withdrawal, in mcg or mg.
- Syringe graduation — the scale of the syringe you measure with. On a U-100 syringe, 100 units equal 1 mL.
The results update as you type.
Worked example
A 10 mg vial reconstituted with 2 mL of diluent has a concentration of 5 mg/mL (5,000 mcg/mL). A draw of 250 mcg is therefore 0.05 mL, which reads as 5 units on a U-100 syringe, and the vial holds 40 draws of that size.
Worked examples for catalogue products
The same arithmetic for four common vials. Each assumes the diluent volume shown; change it in the calculator to see any other concentration.
- BPC-157, 10 mg + 2 mL → 5 mg/mL (5,000 µg/mL). A 0.1 mL draw contains 500 µg.
- GHK-Cu, 50 mg + 5 mL → 10 mg/mL. A 0.05 mL draw contains 500 µg.
- MOTS-c, 10 mg + 2 mL → 5 mg/mL. Prepare fresh and portion; see the MOTS-c overview for why.
- BPC-157 / TB-500 blend, 10 mg + 10 mg + 2 mL → 5 mg/mL of each. Run the calculator once per component with the same diluent volume. See peptide blends in research.
If the certificate reports net peptide content, multiply the label mass by it before entering the mass; sequence, molecular weight and net peptide content explains the correction.
The formulas behind the calculator
- Concentration = peptide mass ÷ diluent volume
- Volume per draw = quantity per draw ÷ concentration
- Syringe units (U-100) = volume per draw in mL × 100
- Draws per vial = peptide mass ÷ quantity per draw
Keep the units consistent: 1 mg = 1,000 mcg.
Tips for accurate results
- Choose a diluent volume that gives a draw volume you can measure precisely. Very small draw volumes are harder to read accurately on the syringe scale.
- Add the diluent slowly down the inside wall of the vial and swirl gently; do not shake. The full procedure is in our guide to reconstituting a lyophilised peptide.
- Once reconstituted, store the vial as described in our peptide storage guide.
U-100 syringe units to millilitres
A U-100 syringe is graduated in 100 units per millilitre, so one unit is 0.01 mL regardless of what is in it. The calculator reports draws in both; this table is the same conversion for quick reference.
| 5 units | 0.05 mL | 50 units | 0.50 mL |
| 10 units | 0.10 mL | 60 units | 0.60 mL |
| 20 units | 0.20 mL | 75 units | 0.75 mL |
| 25 units | 0.25 mL | 100 units | 1.00 mL |
A U-40 syringe is graduated at 40 units per millilitre (one unit = 0.025 mL) and will mislead you if used with the figures above; the calculator assumes U-100. Draws under about 1 unit cannot be measured accurately on any insulin-type syringe; if the calculator shows one, reconstitute with more diluent.
Frequently asked questions
What does the peptide calculator work out?
Three things from three inputs: the concentration of the reconstituted vial (peptide mass ÷ diluent volume), the volume to draw for a given quantity of peptide, expressed in millilitres and in U-100 syringe units, and how many such draws the vial contains.
How much diluent should I add to a vial?
Enough that each draw is a readable volume on the syringe, typically 10–50 units, and the whole vial stays within the working life of the diluent. For a 10 mg vial and draws of a few hundred micrograms, 1–3 mL is the usual range; use the reverse calculator for a specific concentration.
Why does adding more water change the units I draw?
Because the diluent sets the concentration. The same quantity of peptide is a larger volume at a lower concentration. Doubling the water doubles the units for the same quantity; the amount of peptide in the draw is unchanged.
How do I convert mcg and mg?
1 mg = 1,000 mcg. The calculator accepts either unit for the vial mass and for the quantity per draw; the most common error is entering a milligram figure in the microgram field, which the calculator flags because the quantity per draw then exceeds the vial.
Does the calculator work for a blend?
Yes, one component at a time: enter that component’s mass with the shared diluent volume. In a 10 mg + 10 mg blend reconstituted with 2 mL, each peptide is at 5 mg/mL; their molar concentrations differ with molecular weight. See peptide blends in research.
Should I use bacteriostatic or sterile water?
Bacteriostatic water (0.9% benzyl alcohol) for a vial that will be drawn from repeatedly over up to 28 days; sterile water for single-use preparations, cell-based work or benzyl-alcohol-sensitive peptides. See bacteriostatic water vs sterile water.
What if the certificate reports net peptide content?
Multiply the label mass by the net peptide content before entering it. A 10 mg vial at 85% net peptide content contains 8.5 mg of peptide. See sequence, molecular weight and net peptide content.
Is this calculator for human use?
No. It is a laboratory tool for preparing research solutions. Quantum Peptides products are for in-vitro and preclinical research only and are not for human or veterinary use; the calculator is not guidance on administration of any kind.
Related guides
- How to reconstitute a lyophilised peptide
- How to read a peptide certificate of analysis
- Peptide storage: temperature, light, humidity and shelf life
- Lyophilized research peptides
Quantum Peptides supplies lyophilised research peptides for in-vitro and preclinical laboratory research only. Products are not for human or veterinary use. This calculator performs laboratory arithmetic and is not guidance on administration of any kind.