What this calculator does
Alcohol dilution works out water needed to cut a spirit down from one ABV to a weaker target ABV. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulawater to add = volume × (start ABV − target ABV) / target ABV
The inputs explained
| Field | What to enter |
|---|---|
| Starting ABV (%) | A number, measured in %. Starts at 40. |
| Target ABV (%) | A number, measured in %. Starts at 20. |
| Starting volume (ml) | A number, measured in ml. Starts at 750. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with starting abv
Every other input is held at the calculator’s starting values while starting abv varies. Select any row to load that scenario into the calculator.