Proof ↔ ABV Converter
Live conversion — type in any field
Range: 0–200 proof
Range: 0–100%
Range: 0–175°proof
| Spirit | ABV | US Proof | UK Proof |
|---|---|---|---|
| Beer (typical) | 5% | 10° | 8.75° |
| Wine (typical) | 12% | 24° | 21° |
| Vodka (standard) | 40% | 80° | 70° |
| Gin (standard) | 40–47% | 80–94° | 70–82° |
| Whisky / Whiskey | 40–46% | 80–92° | 70–80.5° |
| Rum (standard) | 40% | 80° | 70° |
| Overproof rum | 63–75% | 126–150° | 110–131° |
| Cask strength whisky | 55–65% | 110–130° | 96–114° |
| Absinthe | 45–74% | 90–148° | 79–130° |
| New make spirit | 60–75% | 120–150° | 105–131° |
| Everclear / Spirytus | 95% | 190° | 166° |
| Azeotrope (max distillable) | 97.2% | 194.4° | 170° |
US Proof vs UK Proof vs ABV
Three different systems exist for measuring alcohol strength — and all three are still in active use today depending on where you are.
ABV (Alcohol by Volume) is the international standard used almost everywhere today. It expresses the percentage of pure ethanol in the total volume of liquid. A spirit at 40% ABV contains 40mL of ethanol for every 100mL of total liquid. ABV is used for all EU labelling, distillation calculations, and scientific purposes.
US Proof is exactly double the ABV percentage. A spirit at 40% ABV is 80 proof in the US. The system dates to early American taxation of alcohol, where 100 proof was defined as the minimum strength at which gunpowder soaked in spirit would still ignite — roughly 50% ABV.
Full explanation of %ABV, US proof, UK proof and the Tralle and Sikes scales.
UK Proof (British proof or Sykes proof) uses a different multiplier — 1.75 — based on a historical hydrometer system developed by Bartholomew Sykes in 1816. It was officially replaced by ABV in the UK in 1980 but still appears on older bottles and in historical recipes.
At 100° UK proof, a spirit is 57.15% ABV — this is why Navy Strength gin and rum is traditionally bottled at 57% ABV.
Why Does Navy Strength Mean 57%?
100° UK proof equals 57.15% ABV. The Royal Navy stored gunpowder and spirits in close proximity on ships. If a spirit was at or above 100° proof (57.15% ABV), it would not prevent gunpowder from igniting if accidentally soaked — a practical safety test. Spirits bottled at this strength became known as Navy Strength, a term still used for high-ABV gins and rums today.
How to Convert Between Proof and ABV
US proof is exactly double the ABV percentage. A spirit at 40% ABV is 80 proof. A spirit at 63.5% ABV is 127 proof. The conversion is always the same: multiply ABV by 2 for US proof, divide US proof by 2 for ABV. This system was standardised in the United States in the 1800s and has remained unchanged.
UK proof uses a different multiplier. The original UK proof system was based on gunpowder ignition testing from the 1700s: a spirit was "at proof" if a gunpowder-soaked cloth would still ignite when wetted with it. This corresponded to approximately 57.15% ABV. The conversion formula is ABV multiplied by 1.75 for UK proof, or UK proof divided by 1.75 for ABV. A 40% ABV spirit is 70 degrees proof in UK notation.
The UK system was legally replaced by ABV labelling in 1980, but you still encounter the old proof figures on vintage bottles, historical recipes, and some export markets. The terms "overproof" and "underproof" from UK usage are still used informally to mean above or below 57.15% ABV.
Proof at Different Stages of Distillation
Understanding proof matters at several points in the distilling process. During the spirit run, distillate comes off the still at varying proof as the run progresses. Pot still hearts typically run between 75 and 62% ABV (150 to 124 US proof). If you are using a parrot alcoholmeter calibrated in proof rather than ABV, this converter lets you cross-reference readings without doing mental arithmetic mid-run.
At bottling, most spirits are reduced to 40% ABV (80 US proof) as the standard minimum for spirits labelling in most markets. Some distillers prefer 46% (92 proof) as this is often considered the threshold above which chill filtration is not required to maintain clarity. Cask strength or barrel proof spirits are typically 55 to 65% ABV (110 to 130 proof) and are bottled without dilution.