Theory · Beginner
Reading ABV in the glass
Bottle strength is not drink strength. Water, juice and syrup all drop the ABV the guest actually drinks.
The number on the bottle is not the number in the glass. A 40% ABV whisky becomes a much softer drink once citrus, sugar and melt are in there. That is the figure that matters for service, tasting notes and a rough standard-drink count.
The working sum
- Multiply each ingredient’s volume (ml) by its ABV, and add those up. That is millilitres of pure alcohol.
- Add all the volumes, including the water you shook or stirred in.
- Alcohol millilitres ÷ total millilitres × 100 is the drink ABV.
Juice, syrup, soda and water are 0% ABV. They still count in the total. Leave them out and you will think the drink is hotter than it is.
Australia labels bottles in % ABV. US proof is twice the ABV — useful when a spec sheet was written in the States, not something you need to put on a menu. An Australian standard drink is 10 g of ethanol. Ethanol weighs about 0.789 g per ml, so you can estimate standard drinks from the same alcohol total.
Why it is worth doing
A 60 ml pour of 40% spirit, neat, is one thing. The same 60 ml inside a sour with 30 ml citrus, 15 ml syrup and about 30 ml of melt is another. Guests feel that difference even if they never ask for the number. When you batch for a keg or a bottled serve, the ABV calculator stops you guessing whether the batch is still a cocktail or has become a punch.
This is a training estimate, not a lab certificate and not a labelling claim. Taste the drink. If it drinks hotter than the number, you are short on water or acid, not short on a spreadsheet.