Ounces to Grams Converter

How do you convert ounces to grams?

Multiply the ounces by 28.3495. The ounce used for food is the avoirdupois ounce, defined as exactly 28.349523125 grams; 28.35 is more precision than any kitchen needs. Sixteen ounces make one pound, or 453.59 grams. Unlike cups and tablespoons, ounces are a weight, so the conversion never depends on the ingredient — an ounce of feathers and an ounce of lead both weigh 28.35 grams; they just take up very different amounts of space.

The trap is the fluid ounce. It sounds the same and is also written "oz", but it measures volume: 1 fluid ounce is 29.57 millilitres. A fluid ounce of water happens to weigh 29.57 grams — close to an ounce — which is why the confusion survives; a fluid ounce of honey weighs about 42 grams and a fluid ounce of flour about 15 grams. If the amount came from a measuring jug, it is fluid ounces and needs the cups to grams converter, not this page.

Rounding on food labels

Manufacturers round. A package marked "4 oz (113 g)" has rounded 113.4 grams down, and "8 oz (227 g)" rounds 226.8 grams up — both are the same honest conversion at label precision. When a recipe and a package disagree by a gram or two, the package weight is the one to cook with.

Why do recipes confuse ounces with fluid ounces so often?

Because the two units share a name, an abbreviation and — for water alone — almost the same number. An ounce is a weight of 28.35 grams; a fluid ounce is a volume of 29.57 ml. A fluid ounce of water weighs 29.57 grams, close enough to 28.35 that the two get treated as interchangeable, and for water, milk and most thin liquids the error stays small. The moment the ingredient is not water-like, the coincidence collapses: a fluid ounce of honey weighs about 42.5 grams, and a fluid ounce of flour weighs barely 15 grams.

The practical check is where the amount came from. If it was weighed, or printed on a package as a net weight, it is ounces and this page converts it. If it was poured into a jug or a measuring cup, it is fluid ounces, and the conversion depends on the ingredient — use the cups to grams converter instead. The grams in a cup of honey page shows the extreme case: honey is so dense that confusing the two ounces throws a recipe off by half.

When does rounding an ounce to 28 grams change a recipe?

Almost never at home-baking scale — and predictably at large scale. Rounding 28.3495 down to 28 loses 0.35 grams per ounce, about 1.2 percent. On a 4-ounce portion of cheese that is 1.4 grams, less than a scale's own flicker, and no sauce will notice. But the error is proportional, so it grows with the batch: at 5 pounds (80 ounces) the shortcut is 28 grams light, enough to matter in a scaled-up bread dough or a commercial recipe where the other ingredients were converted exactly.

The same logic applies in reverse when a recipe was developed with the rounded figure. Older US recipes and some packaging treat an ounce as 28 grams and a pound as 448 grams; cooking those with exact conversions introduces the same 1.2 percent in the other direction, still harmless for a single batch. Where precision genuinely matters — scaling a recipe several times over with the recipe scaler, or converting a full ingredient list — use the exact figures from this page and the pounds to grams converter and let the small numbers take care of themselves.

Frequently asked questions