# alcohol content of liquor: why do Americans use "proof" and Canadians use percentage? **URL:** \ **Category:** Factual Questions\ **Created:** [July 10, 2018, 1:40am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631 "2018-07-10T01:40:38Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [July 10, 2018, 6:54pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/21 "2018-07-10T18:54:33Z")
> [@thelurkinghorror](#): > > The UK uses Imperial (yes, still, in manu cases). The US does not, it uses US Customary. The two systems are mostly the same, but one area where they are markedly different are in liquid measures. And IIRC the US requires the mL to be stated, even if measured in oz. For hard alcohol that is not a concern though, as all measurements are metric, and only given customary nicknames (a fifth is officially 750 mL, but 1/5 gallon is really 757 mL). > > You are required to put ABV on the bottle, proof is optional and is a historical affectation, just like how Canadian whisky can be labeled rye whisky and have 0% rye grain involved. > > BTW, proof = ABV x 2 is not the only definition. The UK used ABV x 1.75, but that system is obsolete. To expand on this. Beer is sold via US Customary, but wine and liquor are taxed and sold based on the metric system. Taxes on distilled spirits have been SI based for a very long time, and there are two primary concerns of the TTB (the regulating body). 1. Taxes 2. Consumer protection (label laws) The primary driver for keeping beer in ounces is to prevent consumer confusion. But the metric measurements on wine and spirits is the _official_ measure. Here is a link that will show some of their concerns, related to the use of centaliters being prohibited to avoid confusion. [https://www.ttb.gov/pdf/notices\_alcohol/notice876.pdf](https://www.ttb.gov/pdf/notices_alcohol/notice876.pdf) Taxation is calculated by alcohol by volume, but proof is used because of not just historical reasons but because consumers are use to it. But proof is added as a consumer tool, and not the official standard. As an example here is the TTB’s requirement for a product to be labeled _whisky_, note how ‘proof’ is in (). > [@](#): > > Spirits distilled from a fermented > mash of grain at less than 95% > alcohol by volume (190 proof) having > the taste, aroma and characteristics > generally attributed to whisky and > bottled at not less than 40% alcohol > by volume (80 proof) ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 10, 2018, 7:00pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/22 "2018-07-10T19:00:40Z")
> [@Dickerman](#): > > In the US, ABV is required for distilled spirits: [https://www.ecfr.gov/cgi-bin/text-idx?SID=07c4ec70d2c2dc7d75796ade19d63d08&mc=true&node=se27.1.5\_137&rgn=div8](https://www.ecfr.gov/cgi-bin/text-idx?SID=07c4ec70d2c2dc7d75796ade19d63d08&mc=true&node=se27.1.5_137&rgn=div8) > > whereas proof is optional. It differs for malt beverages, and wine, I can make out, I think, that that Federal statute dates from 1986. If that is true, it is definitely pertinent to “inertia,” the preceding regional history, etc. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [July 10, 2018, 7:03pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/23 "2018-07-10T19:03:03Z")
To clarify, use of _proof_ is allowed but not required, and if it is used it must be right next to the ABV on products sold in the US and ABV is required. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [July 10, 2018, 7:09pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/24 "2018-07-10T19:09:38Z")
> [@Leo\_Bloom](#): > > I can make out, I think, that that Federal statute dates from 1986. If that is true, it is definitely pertinent to “inertia,” the preceding regional history, etc. That was just an example (related to the rise of mini-bottles). I don’t have access to a historical law library, but I think it was. T.D. ATF–198, 50 FR 8535, Mar. 1, 1985 IIRC there was a voluntary 10 year window from rules in the 1970’s, right around the same time Canada moved away from the UK units and this date aligns with that. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [July 10, 2018, 9:22pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/25 "2018-07-10T21:22:27Z")
> [@pulykamell](#): > > I suspect labels will vary by location. Here in the US, proof is still commonly on bottles. Of course they vary by location. Here they also need to be in English and French. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [July 10, 2018, 9:32pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/26 "2018-07-10T21:32:35Z")
> [@Leaffan](#): > > Of course they vary by location. Here they also need to be in English and French. Then I guess I don’t understand your response to **running coach**. You were curious whether anybody still labels it by proof. Yes, the US quite often does, even if your experience in Canada is different. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [July 10, 2018, 10:36pm UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/27 "2018-07-10T22:36:17Z")
> [@pulykamell](#): > > Then I guess I don’t understand your response to **running coach**. You were curious whether anybody still labels it by proof. Yes, the US quite often does, even if your experience in Canada is different. I don’t understand why you don’t understand my response to Running Coach. I’m not the OP. I was just stating what was on the label of my Smirnoff. 😕 ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [July 11, 2018, 12:54am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/28 "2018-07-11T00:54:33Z")
It looks to me (though this is not stated in the Wikipedia article on alcohol proof) as if the original meaning and use of “proof” was as a relatively simple and easily reproducible “field test” for alcohol content - just wet some gunpowder with a sample of the liquor, and try to light the resulting mixture. The lowest alcohol content where the gunpowder would still burn happens to be 57.15%, but that number didn’t matter at the time - they said “let’s call this 100°, and plain water will be zero”. It follows the sensible tradition of choosing an observable reproducible phenomenon as a nice round number on an arbitrary scale. When, much later, the Americans decided to set a national standard, the “proof” system was obviously well known, and they wouldn’t have wanted to upset the public by eliminating it entirely - but at the same time, the proof scale was arbitrary, and British. 🙂 So, with greater ability than two hundred years earlier to measure alcohol percentage more directly (i.e. without gunpowder), the Americans decided to set 100 proof at 50% alcohol instead of 57.15%. And then, later still, some sane person said “We’re measuring the alcohol percentage anyway, and everyone can understand that as it is, so why continue this proof nonsense?” ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 11, 2018, 2:21am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/29 "2018-07-11T02:21:35Z")
Yeah, and why don’t they spell whisky right! ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [July 11, 2018, 2:25am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/30 "2018-07-11T02:25:00Z")
> [@pulykamell](#): > > Yep. The sizes are all in metric, but the common or nicknames can still be their imperial forebears. We’ve had this thread before, but a 750mL is still called a “fifth” in many parts of the US (it’s the standard term in my location and age group, at least). The 375mL is called a “pint” and the 250mL is called a “half pint.” And the 1.5L is a “handle.” But, yes, all in metric. Wine is metric, too, but beer and malt beverages are usually imperial units, unless they’re imports. In my neck of the woods where most everything is metric, 750 ml are often (50% of the time or so) called two-sixes (26 oz) 1.15 l are forties and the 375s are called mickeys. Can’t say I have heard or seen a 250 ml of spirits but I may have simply passed them by on my way to grab a 40 of Bombay. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [July 11, 2018, 2:29am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/31 "2018-07-11T02:29:41Z")
Oops. I’m a moron. A “half-pint” is 200mL. That’s two brain farts. That’s like the “personal sized” bottle, about the size of a standard flask. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 11, 2018, 3:00am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/32 "2018-07-11T03:00:50Z")
Correct me if I’m wrong here: when Brits say “let me buy you a pint,” that measurement, even given the obviously loose standards of filling a glass by eye, is that still rationally expected to equal more or less a pint in volume? FWIW, older Brit cookbooks routinely use “wine-glass” and “demitasse cup” as liquid volume measurements. And just the other day I read and now can’t remember some strange word Brits use or have used for “half a pint of beer”–what in America is simply called “a short beer.” Anyone know/use it? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 11, 2018, 3:07am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/33 "2018-07-11T03:07:34Z")
> [@FordPrefect](#): > > In my neck of the woods where most everything is metric … 1.15 l are [called] forties and the 375s are called mickeys… Any idea on the etymologies? ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [July 11, 2018, 3:37am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/34 "2018-07-11T03:37:59Z")
> [@Leo\_Bloom](#): > > Any idea on the etymologies? 750 ml is about 26 ounces 1,150 ml is about 40 ounces Mickey: I have no idea ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [July 11, 2018, 3:46am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/35 "2018-07-11T03:46:33Z")
Note to my previous post: Real ounces, not American ounces. 🙂 ---
**Author:** ![DavidwithanR](https://avatars.discourse-cdn.com/v4/letter/d/3bc359/32.png) [@DavidwithanR](https://boards.straightdope.com/u/DavidwithanR)\ **Post date:** [July 11, 2018, 3:52am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/36 "2018-07-11T03:52:04Z")
More “logic” (or not): 1,130 ml = 1 quart (Imp.) 750 ml = one-fifth of a gallon (US) ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [July 11, 2018, 4:18am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/37 "2018-07-11T04:18:51Z")
> [@DavidwithanR](#): > > Note to my previous post: Real ounces, not American ounces. 🙂 Maybe, but American fluid ounces are slightly bigger (29.57 mL vs 28.41 mL), so maybe they should be the “real” ounces. 🙂 ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [July 11, 2018, 4:21am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/38 "2018-07-11T04:21:53Z")
“Forty” is a very common term used to refer to 40 oz. bottles of malt liquor ([Malt liquor - Wikipedia](https://en.wikipedia.org/wiki/Malt_liquor#Forty-ounce)) - I’ve never come across spirits sold in that size. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [July 11, 2018, 6:06am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/39 "2018-07-11T06:06:32Z")
> [@Leo\_Bloom](#): > > Yeah, and why don’t they spell whisky right! The origin is Irish, and they spell it the correct way, whiskey 🙂 > [@pulykamell](#): > > Maybe, but American fluid ounces are slightly bigger (29.57 mL vs 28.41 mL), so maybe they should be the “real” ounces. 🙂 True, Imperial pints and quarts and gallons are bigger, while metric uses base-10. But US uses base-2, and Imperial uses base-WTF???, so when Skynet takes over the US system will reign supreme! ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [July 11, 2018, 6:40am UTC](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631/40 "2018-07-11T06:40:30Z")
> [@Leo\_Bloom](#): > > And just the other day I read and now can’t remember some strange word Brits use or have used for “half a pint of beer”–what in America is simply called “a short beer.” Anyone know/use it? Not simply ‘a half’ ? > [@thelurkinghorror](#): > > The origin is Irish, and they spell it the correct way, whiskey 🙂 You mean _uisce_ (beatha) [Previous page](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631.md?page=1) [Next page](https://boards.straightdope.com/t/alcohol-content-of-liquor-why-do-americans-use-proof-and-canadians-use-percentage/817631.md?page=3)