Solve the dilution equation C₁V₁ = C₂V₂ in seconds. Pick the value you need, enter the other three with their units, and read off how much stock solution and diluent to mix.
Choose the value to solve for, enter the other three and the result updates as you type.
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Diluting a solution adds solvent without adding solute, so the amount of solute stays constant: concentration × volume before equals concentration × volume after. That conservation is the whole equation. Knowing any three of stock concentration (C₁), stock volume (V₁), final concentration (C₂) and final volume (V₂) fixes the fourth.
You need 50 mL of a 2 mM working solution from a 10 mM stock. Solving for V₁ gives V₁ = C₂V₂ ÷ C₁ = (2 mM × 50 mL) ÷ 10 mM = 10 mL. Measure 10 mL of stock, then add diluent up to 50 mL — that is 40 mL of diluent for an ideal solution.
The calculator converts freely within a unit family: molar units (M, mM, µM, nM), mass per volume (g/L, mg/mL, µg/mL, ng/µL and friends) and percent. It will not convert across families, because turning a percentage into molarity needs the substance's molar mass and density — values the equation itself does not contain. Pick the family your protocol uses and stay in it.
This page solves for concentrations and volumes directly. If your protocol speaks in fold-changes ("dilute 25×"), use the dilution factor calculator; if it speaks in parts ("mix 1:10"), use the dilution ratio calculator. The three describe the same physical act with different bookkeeping.
Every result comes from the dilution equation C₁V₁ = C₂V₂, rearranged for the value you ask for and applied exactly as written. Inputs are first converted to a base unit within their family (molar to M, mass per volume to g/L, volume to L), the equation is solved, and the answer is converted back to the unit you selected. The formula used is printed under each result so you can check it by hand.
The equation assumes the solute is conserved and volumes are additive, which holds for ordinary dilute solutions. The calculator is tested against the worked examples on this page and against reference values before every release.
This calculator is for general laboratory and household reference. Verify critical preparations — such as pharmaceutical, clinical or safety-relevant dilutions — against your protocol and a qualified professional.
Short answers to the questions people ask most about dilutions.