White vinegar

One US cup of white vinegar weighs 238 grams (8.4 ounces). Going the other way, 100 grams is about 0.42 cups.

Also called distilled white vinegar, distilled vinegar, white distilled vinegar, spirit vinegar, 5% vinegar.

Condiments and sauces compared: cup weights side by side, the source behind each, and why they differ.

A cup of white vinegar weighs 238 g (8.4 oz), a density of 1.006 g/mL, less than 1% heavier than the same cup of water. A tablespoon weighs 14.9 g and a teaspoon 5 g. USDA weighs a cup at 238 g, and a 5% solution of acetic acid in water, which is what white vinegar is, measures 1.0052 g/mL at 20 °C, 237.8 g per cup.

White vinegar, sold as distilled vinegar in the US and spirit vinegar in Britain, is made by letting acetic acid bacteria ferment a dilute distilled alcohol, usually from corn or other grain, and then diluting the result with water to a standard strength. In American supermarkets that strength is almost always 5% acidity, printed on the label as 5% or "50 grain". Nothing else of note is dissolved in it: USDA's record lists 94.8 g of water per 100 g and only 0.04 g of carbohydrate. It goes into pickles and quick pickles, marinades, slaws, homemade buttermilk and cleaning.

The physics is unusually simple. Pure acetic acid is only slightly denser than water, about 1.05 g/mL, so a 5% solution weighs only half a percent more than water. Engineering ToolBox's table of aqueous solutions gives 5% acetic acid as 1.0052 g/cm³ at 20 °C, and Alliance Chemical's specification for food-grade 5% acetic acid gives the same 1.0052. USDA's Standard Reference record for distilled vinegar (FDC 172237) weighs a cup at 238 g and a tablespoon at 14.9 g, 1.006 g/mL. Measured vinegar and the textbook solution agree within 0.1%, which is about as close as two sources can get. USDA's measured cup is published.

Strength barely moves the figure. Cleaning vinegar at 6% and industrial vinegar at 10% are stronger, and 10% acetic acid weighs 1.012 g/mL, 239.5 g per cup, still within 1% of the 5% figure. Pickling vinegar sold in the US is the same 5% as table vinegar, so a pickling recipe can use this figure unchanged.

Labels give the serving as 1 tbsp (15 mL), a volume rather than a weight, because the FDA reference amount for vinegar, a major condiment, is 1 tablespoon. For vinegar, unlike thicker condiments, writing grams equal to millilitres would be almost right: 15 mL weighs 15.1 g.

Practical guidance: use 238 g per cup, 119 g per half cup, 59.5 g per quarter cup, 14.9 g per tablespoon and 5 g per teaspoon. A gallon of white vinegar weighs about 3.81 kg, 8.4 lb, and a 32 fl oz bottle about 952 g. For pickling brines given in cups, weighing the vinegar and water together on a scale is quicker than measuring each, and because vinegar weighs so nearly what water weighs, a liquid measuring cup filled to the line is accurate to within a couple of grams.