Proof & ABV Converter

It depends entirely on Input Unit. In US Proof, ABV%, or UK Proof mode, Input Value and ABV move together -- more proof or more percentage both mean more alcohol. In Specific Gravity mode the relationship flips: specific gravity measures density relative to water, and alcohol is less dense than water, so a LOWER specific gravity reading (closer to pure-alcohol density) corresponds to a HIGHER ABV, not a lower one.

No, and they aren't meant to be. US Proof is always exactly 2x ABV by definition (so 80 US proof means 40% ABV). UK Proof (Sikes) is an older scale where 100 degrees corresponds to 57.15% ABV rather than 50%, which works out to UK Proof being about 7/8 of the equivalent US Proof figure -- an 80 US-proof / 40% ABV spirit reads as roughly 70 degrees on the UK scale, not 91. You can enter a UK Proof figure directly by selecting "UK Proof (Sikes)" as the Input Unit.

The calculator reports 0% ABV and 0 proof. A specific gravity at or above 1.0 means the liquid is at or denser than plain water, which this model treats as containing no measurable alcohol -- real spirit hydrometer readings for any drinkable ABV fall below 1.0, typically in the 0.93-0.99 range for spirits under 50% ABV and down toward pure ethanol's 0.789 at 100% ABV.

Yes -- Input Unit changes which formula the calculator runs, so entering the same number under the wrong unit selection produces a meaningless result. A label reading "80 proof" should be converted with Input Unit set to US Proof, not ABV%, since 80 interpreted as a percentage would describe a spirit with no plausible alcohol content. A pre-1980 British label reading "70 degrees proof" should use UK Proof (Sikes), not US Proof -- the two scales disagree by a factor of 7/8.