Every reconstitution calculator does one thing: divide the mass of peptide by the volume of diluent. Once you understand that, you can check any calculator, or skip it.
Last updated 27 October 2026 · Written by the SHLabz research team
For the hands-on procedure, see our reconstitution guide.
The Core Formula
Concentration = mass of peptide ÷ volume of diluent
If a vial contains 10 mg and you add 2 ml of bacteriostatic water, the concentration is 10 ÷ 2 = 5 mg/ml.
Useful Conversions
| 1 mg | 1,000 µg (micrograms) |
| 1 ml | 1,000 µl (microlitres) |
| 5 mg/ml | 5 µg/µl |
Worked Laboratory Examples
Example 1: set a target concentration. You need 2 mg/ml from a 10 mg vial. Volume = mass ÷ concentration = 10 ÷ 2 = 5 ml of diluent.
Example 2: how much solution holds a given mass. At 5 mg/ml, how much solution contains 250 µg (0.25 mg) for an assay? Volume = 0.25 ÷ 5 = 0.05 ml, which is 50 µl.
Example 3: preparing a working dilution. To dilute a 5 mg/ml stock to 0.5 mg/ml in 1 ml final volume, use C1 × V1 = C2 × V2: 5 × V1 = 0.5 × 1, so V1 = 0.1 ml stock plus 0.9 ml diluent.
Common Mistakes
- Mixing mg and µg. A factor-of-1,000 error. Write units on every line.
- Ignoring net content. A “10 mg” vial may contain slightly more or less actual peptide; the certificate’s quantity result tells you. See net content explained.
- Assuming the powder adds volume. For small masses it is negligible; for very high-mass vials, measure final volume.
- Not labelling. Write concentration, date and diluent on the vial. See vial labels.
Choosing a Volume
A larger diluent volume gives a more dilute solution that is easier to measure accurately with standard pipettes; a smaller volume gives a more concentrated stock that takes up less space and can be diluted later. Pick the volume that suits your pipettes and protocol.
Why Pens and Sprays Skip This
Pre-filled pens and nasal sprays arrive at a fixed concentration, so there is nothing to calculate. See format guide.
The Short Version
Concentration equals mass divided by volume. Keep units consistent, use C1V1 = C2V2 for dilutions, account for net content, and label every vial.
Frequently Asked Questions
What does a reconstitution calculator do? Divides peptide mass by diluent volume.
How many µg in a mg? 1,000.
Does net content matter? Yes, for exact work.
Which diluent? Usually bacteriostatic water; see BAC vs sterile water.
This guide covers laboratory calculations only and is not guidance for human or animal use.
This article is provided for general research and educational purposes only. All SHLabz products are sold strictly for laboratory research use and are not intended for human or veterinary consumption, diagnosis, treatment, or prevention of any disease. Nothing in this article constitutes medical advice. Always consult a qualified professional and comply with applicable local regulations regarding the handling and use of research compounds.
