Dilution Calculator
Solve C₁V₁ = C₂V₂ for any unknown. Enter the three values you know, leave the one you want blank, and get the answer instantly — with the solvent volume to add.
Fill in any three values — the fourth is solved automatically. (3 more to go.)
All dilution & concentration calculators
A focused toolkit for the lab bench, classroom and workshop, grouped by the common types of dilution. Every tool is free and shows the formula it uses.
Lab & research
Find molarity from mass and molecular weight, or the mass needed for a target molarity.
Convert between moles, volume, and molar concentration (mol/L) in any direction.
Dilute a solution with C₁V₁ = C₂V₂ — solve for stock volume, final concentration or volume.
Find the concentration after dilution from stock concentration, stock volume and final volume.
Dilute a stock solution to a target concentration with full unit switching.
Convert mg/mL to molarity (and back) using molecular weight — both directions.
Work out % w/v and % v/v solutions — grams or mL of solute for any volume.
Build a fold-dilution series with concentration and transfer volumes per tube.
Convert between pH and hydrogen-ion concentration [H⁺], plus pOH and [OH⁻].
Calculate DNA or RNA concentration in ng/µL from an A260 reading and dilution factor.
Working antibody dilutions like 1:500 or 1:1000 — antibody and diluent volumes.
Seed cells to a target density — stock suspension and medium to add.
Buffer volume to resuspend a lyophilized oligo, primer or peptide to µM.
Ratios, percentages & ppm
Turn a 1:N ratio into exact stock + solvent volumes for any final amount.
Dilute a percent stock to a lower % — stock and water volumes straight from % to %.
Dilute a ppm stock to a target ppm, with percent ⇆ ppm conversion built in.
Parts per million ⇆ mg/L ⇆ percent, plus the mass of solute for a target ppm.
Household & everyday
Dilute 35%, 12% or 6% hydrogen peroxide down to 3% or any target strength.
Proof down spirits by ABV — get the exact water to add to hit a target %.
Lower ABV by adding water — the exact water to add to reach a target ABV.
Dilute cleaning vinegar (e.g. 30%) down to 5% or any target — vinegar and water volumes.
Drops of essential oil for a safe 1%, 2% or 3% blend in any carrier.
How the dilution calculator works
Diluting a solution means lowering its concentration by adding more solvent while keeping the amount of solute the same. Because the moles of solute do not change, the product of concentration and volume is conserved:
C₁ and V₁ are the concentration and volume of the concentrated stock; C₂ and V₂ are the concentration and volume after dilution. Rearranging lets you solve for whichever value you are missing — the calculator above does this automatically when you leave one field empty.
Worked example
You have a 10 M stock and need 50 mL of a 1 M working solution. Set C₁ = 10 M, C₂ = 1 M, V₂ = 50 mL, leave V₁ blank: V₁ = (1 × 50) / 10 = 5 mL of stock, topped up with 45 mL of solvent to reach 50 mL.
Choosing the right tool
- Need molarity from a mass? Use the molarity calculator.
- Working from a ratio like 1:10? Use the dilution ratio calculator.
- Making a tenfold series? Use the serial dilution calculator.
Frequently asked questions
›What is the dilution formula?
The core dilution equation is C₁V₁ = C₂V₂, where C₁ and V₁ are the concentration and volume of your stock solution, and C₂ and V₂ are the concentration and volume after dilution. Because it is a balance, you can solve for any one of the four values when you know the other three.
›How do I dilute a stock solution to a lower concentration?
Enter your stock concentration (C₁), the final concentration you want (C₂), and the final volume you need (V₂). Leave V₁ blank. The calculator returns the volume of stock to take, and the amount of solvent to add equals V₂ minus V₁.
›Do the units have to match?
Yes — C₁ and C₂ must share the same concentration unit, and V₁ and V₂ must share the same volume unit. The equation is a ratio, so as long as each pair matches, the result is correct in those units. Use the unit selectors to keep them consistent.
›How do I calculate a dilution?
Decide which value you need, then rearrange C₁V₁ = C₂V₂. To find the stock volume, use V₁ = (C₂ × V₂) ÷ C₁; to find the final concentration, use C₂ = (C₁ × V₁) ÷ V₂. Enter the values you know above and the calculator does the arithmetic and tells you how much solvent to add.
›Can I do a dilution conversion between ratios, percent and ppm?
Yes — pick the matching calculator from the hub above. Use the dilution ratio calculator for 1:N ratios, the percentage dilution calculator for % to %, and the ppm dilution calculator for parts per million (remember 1% = 10,000 ppm). They all rest on the same conservation of solute.
›Is this dilutions calculator free?
Yes. Every calculator on DilutionCalc is free, runs entirely in your browser, needs no sign-up, and never sends your numbers to a server.