How to use it
- For each ingredient, enter the amount and its ABV (spirits are usually 37.5–50 %, liqueurs 15–30 %, fortified wines and vermouth about 15–22 %, juice and syrup 0 %). Leave unused rows at 0.
- Set the water from ice as a percentage of the mixed volume, or 0 for a drink with no ice melt.
- Read the strength of the finished drink, the strength before ice and the US proof.
The formula
- Pure alcohol = Σ (amountᵢ × ABVᵢ ÷ 100)
- ABV before ice = pure alcohol ÷ total amount × 100
- Volume after ice = total amount × (1 + dilution ÷ 100)
- ABV of the drink = pure alcohol ÷ volume after ice × 100
Worked example
2 oz of a 40 % spirit, 1 oz of a 20 % liqueur and 1 oz of lime juice:
- alcohol: 2 × 0.40 + 1 × 0.20 + 1 × 0 = 1 oz;
- volume 4 oz, so 25 % before ice;
- with 20 % dilution the drink is 4 × 1.2 = 4.8 oz, and 1 ÷ 4.8 = 20.8 % ABV, 41.7 proof.
Tips
- Top-ups such as soda or tonic count as ingredients at 0 %.
- Bitters are strong but used in dashes; they barely move the result.
- To compare drinks, keep the same dilution for each: the difference between stirred and shaken often matters more than a quarter ounce of spirit.
- For the alcohol units or standard drinks in a glass, use the alcohol units calculator with the result.