The twenty-five sizes
On this page9
The litre sizes
3.75 L, 3 L, 2 L, 1.8 L, 1.75 L, 1.5 L and 1.0 L. The large end, which in practice is handles, party sizes and a few traditional formats.
The nine hundreds and seven hundreds
945 mL, 900 mL, 750 mL, 720 mL, 710 mL and 700 mL. Six authorized sizes within 245 mL of each other, which is the clearest sign that this list is a historical settlement rather than a design.
The middle
570 mL, 500 mL, 475 mL, 375 mL, 355 mL, 350 mL and 331 mL. Seven sizes between a third of a litre and a bit over half.
The small end
250 mL, 200 mL, 187 mL, 100 mL and 50 mL. Splits, airline miniatures and samples.
Why there are so many
The list reconciles metric conversion with sizes the trade already used, on both sides of the Atlantic, across spirits that arrived in the US at different times. 710 mL is a US pint and a half in metric dress; 700 mL is the European bottle.
It applies to domestic and imported alike
The regulation says so explicitly: authorized "whether domestically bottled or imported". There is no route by which an unusual size is acceptable because it came from somewhere else.
And there is one historical exception
Imported spirits in their original containers entered into customs custody before 1 January 1980, or bottled before that date with the right certification, are not subject to the standards of fill. That is an exception about old stock, not a route for new product.
What to do with the list
Print it and keep it next to the bottle supplier catalogue. Every bottle conversation starts with whether the size is on it, and that single check prevents the most expensive mistake available in this craft.