About this dilution calculator
The amount of solute stays the same when you add solvent, so C₁ × V₁ = C₂ × V₂. Solve for the stock volume: V₁ = C₂ × V₂ ÷ C₁. To make 100 mL of 2 M from 10 M stock: 2 × 100 ÷ 10 = 20 mL stock, topped up with 80 mL water. Works for any concentration unit as long as C₁ and C₂ match.