Ever wondered why the standard whiskey bottle is 750 milliliters (ml) in the U.S. and 700 ml in Europe? As a result of a federal regulation that alcohol be sold based on metric conversions of United States customary units, much of the world’s best whiskies have been kept out of the United States. What does that have to do with the discrepancy in liquid volume, you ask? The answer may leave you scratching your head.

Back in the mid to late 1970’s, the Alcohol and Tobacco Tax and Trade Bureau – or ATTTB – (a former subdivision of The Bureau of Alcohol Firearms and Tobacco that is now a part of the Department of the Treasury), regulated all aspects of the production, sale and importation of distilled spirits. At the time, there was a huge push for the U.S. to adopt the metric system and it looked like the government might actually go through with the change.

Before that was decided, the ATTTB decided to switch bottle sizes from ounces to ml when there was a push for the country to join the rest of the world in using the metric system. The standard-sized ‘fifth’ (1/5 of a gallon) nearly equaled 750 ml, so they decided that would be the simplest transition for domestic bottlers.

Concerned that spirit distributors would try to sell 700 ml bottles at the same price as 750 ml bottles, the ATTTB decided to standardize the 750 ml bottle and ban the importation of the 700 ml bottles, ostensibly to alleviate any concern about fraud for the consumers. Surely, it must have involved underlying tax complications for the government, but branding the regulation as ‘protecting the customer’ made the arbitrary sanction more palatable.

Thus, only bottles that conformed to Rule 27 CFR 5.74a: ‘Metric standards of fill – distilled spirits bottled after December 31, 1979’ could be imported for resale (that is, bottles that fit the appropriate conversions based of the original Imperial measurements). That excluded an awful lot of good whiskies from the United States market. Some have tried to petition the ATTTB for a change, but one man’s 2013 attempt failed to meet the signature requirements.

Does that mean we at least get more ‘bang for our buck’ here in the U.S.? That depends, really, on your location, the spirit, and how your home state taxes liquor. The difference of 50 ml is only about the size of an airplane bottle. If you’re in California, for example, you will pay much less per ml. But if you’re drinking the same imported scotch in Washington State, you’re definitely paying more per ml. Since the cost of 700ml bottles is variable across Europe as well, the comparable value to the U.S. bottles also depends on where you buy.

For example, the cost to purchase a bottle of 10YO Laphroaig in the U.K. is roughly $52.40 U.S. dollars (700ml) from the distillery. To purchase the same bottle in the U.S., you will pay roughly $53.00 in California for 750 ml but nearly $68.00 in Washington State (based on a sampling of stores). Thus, you do get more bang for your buck in California than if you purchased a bottle from the U.K.