Dilution Calculator

Diluting a solution means adding solvent — usually water or buffer — without adding any more solute. The solute is just spread through a larger volume, so it becomes less concentrated. Because the amount of solute never changes, concentration times volume stays the same before and after. That single fact is the whole calculator.

The everyday case: you have a concentrated stock and want a set volume at a lower concentration.

1. 1

   Identify what you know

   Write down the stock concentration C₁, the concentration you want C₂, and the final volume V₂ you need.

   C₁ = 2 M, C₂ = 0.5 M, V₂ = 100 mL
2. 2

   Solve for the stock volume

   Rearrange to V₁ = (C₂ × V₂) ÷ C₁ and plug the numbers in to find how much stock to measure out.

   V₁ = (0.5 × 100) ÷ 2 = 25 mL
3. 3

   Add solvent up to the final volume

   Subtract to find the solvent: V₂ − V₁. Measure the stock, then bring it up to the final volume with solvent.

   100 − 25 = 75 mL solvent
4. 4

   Mix

   Combine and invert or vortex to mix. The solution is now at the target concentration.

   25 mL stock + 75 mL solvent → 100 mL of 0.5 M

Molarity, fold-strength buffers, and mass-per-volume stocks all use the identical rearrangement. Only the units on the answer change.

When one dilution can't span the range you need, you chain them. A serial dilution applies the same fold-change down a row of tubes, multiplying the dilution at every step.

C₁V₁ = C₂V₂ works with any unit that scales linearly with the amount of solute. Keep both concentrations in the same one.

Set your stock concentration and read the final concentration, percent, and ratio for every common dilution factor at once.

The handful of facts that keep dilutions accurate.

Common questions