# "Proof" on liquor **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2016, 7:38pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372 "2016-12-10T19:38:09Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Shinna\_Minna\_Ma](https://avatars.discourse-cdn.com/v4/letter/s/f08c70/32.png) [@Shinna\_Minna\_Ma](https://boards.straightdope.com/u/Shinna_Minna_Ma)\ **Post date:** [December 10, 2016, 7:38pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/1 "2016-12-10T19:38:09Z")
Where and why did putting “proof” on bottles of liquor develop? Why couldn’t the manufacturers simply write the percentage of alcohol? ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [December 10, 2016, 8:09pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/2 "2016-12-10T20:09:31Z")
Mainly because there was no way to measure alcohol percentage when the proof system was created. [Wikipedia says:](https://en.wikipedia.org/wiki/Alcohol_proof) > [@](#): > > The term proof dates back to 16th century England, when spirits were taxed at different rates depending on their alcohol content. Spirits were tested by soaking a pellet of gunpowder in them. If the gunpowder could still burn, the spirits were rated above proof and taxed at a higher rate. Gunpowder would not burn in rum that contained less than 57.15% ABV. Therefore, rum that contained this percentage of alcohol was defined to have 100 degrees proof. The gunpowder test was officially replaced by a specific-gravity test in 1816. > > From the 18th century until 1 January 1980, the UK measured alcohol content by proof spirit, defined as spirit with a gravity of  12⁄13 that of water, or 923 kg/m3, and equivalent to 57.15% ABV. > > The value 57.15% is very close to the fraction  4⁄7 = 0.5714. Thus, the definition amounts to declaring that 100° proof spirit has an ABV of  4⁄7. From this, it follows that to convert the ABV (expressed as a percentage standard rather than as a fraction) to degrees proof, it is only necessary to multiply by  7⁄4 = 1.75. Thus pure, 100% alcohol will have 100×( 7⁄4) = 175° proof, and a spirit containing 40% ABV will have 40×( 7⁄4) = 70° proof. > > The proof system in the United States was established around 1848 and was based on percent alcohol rather than specific gravity. 50% alcohol was defined as 100 proof. > > The use of proof as a measure of alcohol content is now mostly historical. Today, liquor is sold in most locations with labels that state its alcohol content as its percentage of alcohol by volume (ABV). ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 10, 2016, 8:33pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/3 "2016-12-10T20:33:13Z")
I also note that, for craft bourbons at least, it’s become common to put the alcohol percentage on the label. Knob Creek is 100 proof; type just as large proclaims it 50% alcohol. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [December 10, 2016, 8:40pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/4 "2016-12-10T20:40:26Z")
So the price of a fifth of a US gallon of 100 proof American booze was only slightly lower than the price of a fifth of an Imperial gallon of 100 proof English booze … it would look like American booze was the better deal … even though it’s less volume of weaker shit … what a deal !!! ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 10, 2016, 9:30pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/5 "2016-12-10T21:30:47Z")
> [@watchwolf49](#): > > … it would look like American booze was the better deal … even though it’s less volume of weaker shit … what a deal !!! American commerce at its finest. Or is that at its Greatest? 🙂 ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [December 10, 2016, 9:38pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/6 "2016-12-10T21:38:53Z")
The Short Ton … capitalism at it’s finest … ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 10, 2016, 10:24pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/7 "2016-12-10T22:24:34Z")
Taxation on liquor is based on the alcohol content, so the lower the proof, the lower the federal tax. I believe it’s $25 a proof gallon, although it escapes me as to whether that’s a gallon of ethanol or a gallon of 50% alcohol. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [December 10, 2016, 10:49pm UTC](https://boards.straightdope.com/t/proof-on-liquor/774372/8 "2016-12-10T22:49:07Z")
Be warned. If you drink beer in a British pub, the pump label should tell you the ABV. Most beers are around the 3% to 4% mark, but 5% or more is not uncommon. The popularity of micro breweries means even more high strength beers are available, so be careful.