Oyster sauce

One US cup of oyster sauce weighs 289.1 grams (10.2 ounces). Going the other way, 100 grams is about 0.35 cups.

Also called oyster flavored sauce, oyster-flavored sauce, oyster flavoured sauce, Chinese oyster sauce, hao you.

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

A cup of oyster sauce weighs about 289 g (10.2 oz), a fifth more than a cup of water. Roland's bottles, USDA's tablespoon and Australia's food standards table agree within half a percent.

Oyster sauce is a thick, dark-brown Chinese sauce made from oyster extract with sugar, salt and starch. It gives stir-fries, braised greens, noodles and marinades a savoury, slightly sweet gloss. Most bottles in US shops are labelled "oyster flavored sauce", because the oyster extract is one ingredient among several.

The best measurement comes from Roland Foods, which gives both the volume and the net weight of its bottles. Its 7.03 fl oz bottle, twelve to a case with a case net weight of 6.72 lb, holds 254.0 g in 207.9 mL: 1.2218 g/mL, 289.1 g a cup. Roland's 59.1 fl oz foodservice bottle comes to 289.0 g. USDA's ready-to-serve oyster sauce record weighs a tablespoon at 18 g, 288 g a cup. Food Standards Australia New Zealand's table of specific gravities, compiled from published values, lists Asian oyster sauce at 1.22, 288.6 g a cup. The three are 0.4% apart.

King Arthur Baking's chart has no oyster sauce row.

The physical check: oyster sauce is a salty syrup. Roland lists water first, then sugar and salt, then oyster extract and starch. Dissolved sugar and salt are what make a sauce heavier than water: each 10% of salt adds about 7% to its weight and each 10% of sugar about 4%. A density of 1.22 fits a sauce with roughly a third or more of its weight in sugar, salt, starch and extract, which is what a thick, glossy sauce looks like. One source does not fit: USDA's composition table for the same record gives about 80% water and 11% carbohydrate, which would predict only about 1.10. Its own tablespoon, 18 g, says 1.22. The weighed figures all agree, so this site publishes them; the composition table describes a thinner sauce than the ones weighed.

Brands do differ a little. Thicker premium oyster sauces with more sugar and starch weigh slightly more per spoon, thinner budget ones slightly less, and the difference between them is a few percent, inside the 5% this site allows for liquids.

Practical guidance: use 289 g per cup, 72 g per quarter cup, 18 g per tablespoon and 6 g per teaspoon. Oyster sauce is thick and clings to the spoon, so a scraped-out tablespoon is often a gram short; for marinades and sauces that is fine, but when a recipe gives grams, weigh it straight into the bowl. Refrigerate the bottle after opening.