The units an American recipe names, at their exact size
A recipe cup holds 236.59 millilitres, a tablespoon 14.79 and a teaspoon 4.93. Two of the seven units below carry a second size under the same name, and one pair of them measures two different quantities while sharing a word. Those are the cases worth knowing; the rest is arithmetic.
The seven units and what each one is worth
| Unit | Short | Size, defined | The same thing said another way |
|---|---|---|---|
| cup | cup | 236.59 ml | 16 tablespoons, or 8 fluid ounces |
| tablespoon | tbsp | 14.79 ml | 3 teaspoons, or half a fluid ounce |
| teaspoon | tsp | 4.93 ml | A third of a tablespoon |
| milliliter | ml | 1 ml | The metric base for volume |
| fluid ounce | fl oz | 29.57 ml | 2 tablespoons, and a volume rather than a weight |
| gram | g | 1 g | A thousandth of a kilogram, and what a scale reads |
| ounce | oz | 28.35 g | A sixteenth of a pound, and a weight rather than a volume |
Volume units are given in millilitres and weight units in grams, each to the figure its definition fixes rather than the figure a recipe rounds it to.
A fluid ounce and an ounce are two different quantities
One word does the work of two units here, and swapping them changes the amount of food. A fluid ounce measures space, 29.57 millilitres of it. An ounce measures mass, 28.35 grams. Nothing converts one into the other until you say what is in the cup, because you are converting a volume into a weight and that needs the ingredient.
Water is where the two look interchangeable, and that coincidence is the reason the mix-up spreads. Our methodology page works through what the eight-ounce rule of thumb does to milk, honey and oil once you carry it past water. To do the conversion for a real ingredient, the converter holds a measured weight for each of the twenty we cover.
The cup on a nutrition label is not the cup in the recipe
American kitchens run two cups. The customary cup, the one recipes are written against, is 236.59 ml. The cup on a nutrition panel is 240 ml, set for labelling rather than for baking, which puts the two 3.41 ml apart. Both are called a cup, and a carton and a recipe mean different ones.
The tablespoon does the same trick in miniature. Its defined size is 14.79 ml, because it is half a fluid ounce, and that decimal is awkward enough that recipes, labels and spoon sets all print 15. The gap is 0.21 ml, small enough to ignore in one spoonful and large enough to notice by the time a recipe asks for eight.
Coming back the other way, from grams
A European recipe names a round weight where an American one names a vessel, and 100 grams is the roundest of them. What that weight becomes in cups depends on the food, because the gram measures mass and the cup measures space, so flour and honey answer differently to the same number. Each of these carries the working for one weight of one ingredient, with the source for the cup it starts from, and the converter handles any amount the list does not.
- 100 Grams All-purpose flour to Cups
- 100 Grams Granulated sugar to Cups
- 100 Grams Butter to Cups
- 100 Grams Milk to Cups
- 100 Grams Water to Cups
- 100 Grams Brown sugar to Cups
- 100 Grams Honey to Cups
- 100 Grams Rice (uncooked) to Cups
- 100 Grams Rolled oats to Cups
- 100 Grams Cocoa powder to Cups
Where the differences that matter live
A unit's size stops being arithmetic the moment the recipe comes from another country, or the moment you fill the spoon differently, and those figures belong to the pages that measured them. A cup means anything from a Japanese 200 ml to a British 284 on cup sizes around the world. The spoon splits the same way, with Australia at 20 ml and Slavic recipes at 18, on tablespoon sizes by country. How high you heap it moves a spoonful further than any national difference does, which heaped versus level spoons takes apart. What a cup of a given food weighs sits on that food's page, each with the authority that weighed it, from flour to honey, and the full set is indexed on ingredients.
Questions about cooking units
- Is a fluid ounce the same as an ounce?
- No. They measure different quantities: a fluid ounce is 29.57 millilitres of space, an ounce is 28.35 grams of mass. A recipe asking for 8 oz of flour wants it weighed, and 8 fl oz of flour is a different amount of flour.
- How many tablespoons are in a cup?
- 16, and 3 teaspoons make each of those, so a cup runs to 48 teaspoons. Those ratios hold only while the cup and the spoon come from the same country.
- Which cup should I use, 236 or 240 millilitres?
- Whichever the recipe was written against, which for anything from a US kitchen is the smaller one. Your measuring cups are already that size, so the question only bites when you are scaling a figure copied off a carton or a nutrition panel.
Sources
NIST Handbook 44 for the customary cup, tablespoon and teaspoon, and for the ounce. US FDA 21 CFR 101.9 for the 240 ml labelling cup. Every figure on the site and the authority behind it are listed on the sources page.