"Federal US standards were established in 1980 but some confusing distinctions remain. American ounce measurements were adjusted to match metric milliliters.
The fifth used to be a standard bottle size for hard liquors and wine, containing one-fifth of one gallon of liquor (or 25.6 ounces). That measure has been adjusted by a fraction to now contain 25.4 ounces, or 750 milliliters (ml).
Slightly larger is the one-liter bottle, containing 1,000 ml, or 33.8 ounces. A standard US quart is 32 ounces so a liter is about two tablespoons more than a quart.
A half-gallon bottle no longer contains a true half gallon (64 ounces) although most people outside the liquor industry still refer to it as such. Today it actually contains 59.2 ounces, or 1.75 liters.
On a smaller scale, the half pint (8 ounces) now contains only 6.8 ounces (200 ml) but the pint-size bottles got fuller, now holding 16.9 ounces (versus the old 16 ounces) to be the equivalent of 500 ml.
A split of wine or champagne contains 6.8 ounces, or 200 ml.
The smallest miniature bottles, often referred to as airplane or hotel bottles, contain 1.7 fluid ounces, or 50 ml."