Alcohol ABV ↔ Proof Converter & Standard Drinks Calculator
Enter a beverage's ABV % and serving size to instantly convert to US proof and UK degrees proof, see grams (and mL) of pure ethanol, and the equivalent "standard drinks" or "units" defined by the US (14 g), UK (8 g), Australia (10 g), Hong Kong (10 g), Canada (13.6 g) and Japan (20 g). Useful for label translations ("80 proof" = 40 % ABV) and for tracking intake against any country's drinking guideline.
ABV must be between 0 and 100 %.
US proof
80
US proof = ABV × 2 (27 CFR 30.42).
UK degrees proof
70.0
100° UK proof = 57.15 % ABV (Sikes hydrometer).
Pure alcohol
14.0g
≈ 17.7 mL
Standard drinks / units by region
Grams per "drink/unit" by region shown in each tile.
Pure-alcohol grams use ethanol density 0.789 g/mL at 20 °C; "standard drinks" follow each region's public-health definition and are not a drinking-limit recommendation.
Formula
US proof = ABV × 2 UK degrees proof = ABV / 57.15 × 100 ethanol_g = volume_mL × (ABV/100) × 0.789 standard_drinks = ethanol_g ÷ {US 14, UK 8, AU 10, HK 10, CA 13.6, JP 20}
- · US proof is defined by the TTB (27 CFR 30.42) as exactly 2 × ABV — so 80 proof = 40 % ABV, 100 proof = 50 % ABV.
- · UK "degrees proof": 100° = 57.15 % ABV (Sikes hydrometer calibration; historically the lowest strength of spirit that would still ignite gunpowder). Conversion ≈ ABV × 1.75. The UK officially retired the proof system on 1 January 1980.
- · Pure-ethanol density is 0.789 g/mL at 20 °C (NIST / WHO standard), giving grams = mL × (ABV/100) × 0.789.
- · Public-health "standard drink" / "unit" sizes vary: US NIAAA 14 g, UK NHS 8 g, Australia NHMRC 10 g, Hong Kong Dept of Health 10 g, Canada CCSA 13.6 g, Japan MHLW 20 g.
- · Rule of thumb: a 12 fl oz / 5 % beer, a 5 fl oz / 12 % wine, or a 1.5 fl oz / 40 % spirit each contain ~14 g pure ethanol — one US standard drink, by design.
- · US fluid ounce (≈ 29.57 mL) is larger than the Imperial fluid ounce (≈ 28.41 mL); but the Imperial pint (568 mL) is larger than the US pint (473 mL) because they hold 20 vs 16 fl oz.
- · Output is a conversion only, not a drinking guideline. HK Dept of Health advises ≤ 2 drinks/day for men, ≤ 1 for women (1 drink = 10 g ethanol).
Frequently asked
What's the ABV of an 80-proof whisky, and how much stronger is 100 proof?
In the US system the rule is simply "proof / 2 = ABV": 80 proof = 40 % ABV, 100 proof = 50 % ABV, 151 proof (Bacardi 151) = 75.5 % ABV. So 100-proof spirit is 25 % stronger than 80-proof (50 / 40 = 1.25×). The UK historical system is different: "100° proof" equals 57.15 % ABV, so the same bottle labelled "Navy Strength gin, 54.5 % ABV" reads ~95° UK proof but 109 US proof — a 13–14-point difference between the two scales, just because of different definitions of "100".
How many NHS units are in a 750 mL bottle of wine (13.5 % ABV), and how many HK standard drinks?
Pure ethanol = 750 × 0.135 × 0.789 ≈ 79.9 g. • NHS unit (8 g): 79.9 / 8 ≈ 9.99 — bang on the NHS "a bottle of 13 % wine is about 10 units" figure. • HK / AU / older Canadian standard drink (10 g): 79.9 / 10 ≈ 8 drinks per bottle. • US NIAAA standard drink (14 g): 79.9 / 14 ≈ 5.7 drinks. The UK low-risk guideline is 14 units per week, so a single bottle uses 71 % of a week's allowance — that's why "a bottle a night" is well over guideline.
Why does a US 1.5-fl-oz shot of 40 % spirit equal exactly one NIAAA 14-g standard drink — is that a coincidence?
It's not a coincidence — NIAAA reverse-engineered the 14 g figure. 1.5 US fl oz = 44.36 mL, × 40 % × 0.789 g/mL = 14.00 g. The same math works for 12 fl oz / 5 % beer (354.9 × 0.05 × 0.789 ≈ 14.00) and 5 fl oz / 12 % wine (147.9 × 0.12 × 0.789 ≈ 14.00). NIAAA deliberately picked 14 g because the three most common American serving sizes — the shot, the standard wine pour and the can/bottle of mainstream beer — all land near 14 g. Other countries didn't bother coordinating: the UK uses 8 g (10 mL of pure ethanol ≈ 8 g), Japan uses 20 g, and Australia/HK use 10 g.
Is "Alc. 4.5 % vol" the same thing as "ABV 4.5 %"?
Yes — they're identical. "% vol", "% v/v", "ABV" and the European "Alc." label all refer to the volume of ethanol divided by the total beverage volume (measured at a reference temperature, usually 20 °C). 4.5 % vol = 4.5 % ABV = 0.045 (decimal). The one to watch out for is "ABW" (alcohol by weight), which still appears on some legacy US beer cans and sports drinks. ABV ≈ ABW × 1.267 (you divide by ethanol's density), so an old-style "3.2 % ABW" beer is actually ≈ 4 % ABV — important when reading historic US state liquor laws.
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