Tools

Laboratory arithmetic, with the working shown

Concentration, dilution and molar conversions for sample preparation. Each result shows the calculation it came from, so it can be checked rather than trusted.

These are general laboratory calculators. They do not produce doses, they assume nothing about who or what a solution is for, and they are not a substitute for a validated procedure.

Concentration from solid and diluent

Solid mass in a vial, plus the volume of diluent added, gives the concentration of the resulting solution.

Solid in the vial (mg)

Diluent added (mL)

5.000 mg/mL (5000 µg/mL).10 mg ÷ 2 mL. This assumes the solid dissolves completely and adds negligible volume; the vial's stated mass may include salts and water, so measured peptide content can be lower.

Dilution (C₁V₁ = C₂V₂)

How much stock solution to take, and how much diluent to add, to reach a target concentration and volume.

Stock concentration (mg/mL)

Target concentration (mg/mL)

Target volume (mL)

Take 2.000 mL of stock and add 8.000 mL of diluent.(1 × 10) ÷ 5 = 2.000 mL.

Mass to moles

Convert a mass to an amount of substance using molecular weight. Useful when comparing compounds of very different sizes, where equal masses are not equal amounts.

Prefill from the library

Molecular weight (g/mol)

Mass (mg)

704.5 nmol (0.704 µmol).Molecular weights catalogued here are drawn from published sources and should be confirmed against the certificate of analysis for the material in front of you.

Mass unit conversion

Milligrams, micrograms and nanograms, which are a routine source of thousand-fold errors.

Value in milligrams (mg)

1 mg
1,000 µg
1,000,000 ng
0.001 g