Dilution Ratio Calculator
When a Recipe Says "1:4" Instead of a Concentration
Not every dilution instruction comes as a target molarity. Cleaning concentrates, hydroponic nutrients, and darkroom chemistry are routinely specified as a ratio — one part concentrate to some number of parts diluent — and translating that ratio into an actual volume of stock and solvent to measure out is a slightly different calculation than the standard C1V1 = C2V2 dilution.
The Formula
Diluent Volume = Total Volume − Stock Volume
Total Parts is simply the stock parts plus the diluent parts — for a 1:4 ratio, that's 5 total parts, one of which is concentrate.
Where This Calculation Matters
- Cleaning and disinfectant concentrates — commercial products are frequently labeled with a dilution ratio rather than a target concentration.
- Agriculture and hydroponics — nutrient concentrates are mixed at specified ratios to avoid over- or under-feeding plants.
- Photography and darkroom chemistry — developer and fixer solutions are commonly diluted by ratio, such as 1+9 or 1:31.
- Paint and coating mixing — reducers and thinners are often specified as a ratio to the base product.
Worked Example
Preparing 1 liter of a 1:4 (stock:diluent) solution — 5 total parts, 1 of which is concentrate:
Diluent Volume = 1 L − 0.200 L = 0.800 L
That's 200 mL of concentrate brought up to a full liter with 800 mL of diluent.
How to Use This Calculator
- Enter the Stock Parts — the concentrate side of the ratio (e.g. the "1" in 1:4).
- Enter the Diluent Parts — the solvent side of the ratio (e.g. the "4" in 1:4).
- Enter the Desired Total Volume you want to end up with.
- Select Calculate to get the exact stock and diluent volumes needed.
Related Calculations
Working from a target concentration rather than a ratio? The standard Dilution Calculator solves C1V1 = C2V2 directly. To find the concentration a given ratio actually produces, pair this with the Concentration Calculator.