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Cooking measurements: cups, grams and why weight wins

Two people follow the same cake recipe, one gets a moist crumb and the other gets a brick, and the difference is usually not skill. It is how much flour fitted into the cup. Here is what the units mean, where they diverge, and how to convert a recipe without wrecking it.

Written and reviewed by SM Arijul Islam · Last reviewed 20 October 2026 · Editorial standards · Report an error

Volume measures ingredients; weight measures them properly

A measuring cup measures volume, and volume only tells you how much an ingredient weighs if you know its density. Water is easy: 236.6 millilitres is 236.6 grams. Flour is not. The same cup can hold 100 grams of sifted cake flour or 155 grams of flour scooped straight from the bag and packed against the side. That is a 50 percent difference in the most important ingredient in a cake.

Professional bakeries weigh everything for this reason. A digital scale set to grams removes the variable entirely, and it costs less than a good set of measuring cups. If you only make one change to how you bake, make it this one — and if you want the arithmetic of scaling a recipe, the baker's percentages guide covers it.

What one cup actually weighs

These are working figures for US cups (236.6 mL) using the spoon-and-level method. Treat them as the middle of a range, not as constants.

Approximate weight of one US cup, spooned and levelled
Ingredient	Grams	Notes
Water, milk	236	Density close to 1 g/mL
All-purpose flour	120–125	Can reach 150 g if scooped
Bread flour	120–127	Slightly denser than plain flour
Granulated sugar	200	Caster sugar is close to the same
Brown sugar, packed	220	Packing pressure changes this a lot
Butter	227	Two US sticks, half a pound
Honey, syrup	340	Spray the cup to release it
Cocoa powder	85	Very light and easily compacted
Rolled oats	90	Depends heavily on the grind
Uncooked white rice	185	Long grain

Which cup?

There is no single cup. The US customary cup, the metric cup used in Australia, New Zealand and Canada, and the old British imperial cup are three different volumes — and the largest is a full 20 percent bigger than the smallest. A recipe from a 1970s British cookbook and a recipe from a modern American blog are not using the same unit, even though both say "cup".

Cup and spoon volumes in millilitres
Measure	Millilitres	Notes
US customary cup	236.588	8 US fluid ounces
Metric cup	250	Australia, New Zealand and Canada
Imperial cup	284	Older British recipes; about 20% larger than the US cup
US tablespoon	14.79	Three teaspoons
Imperial tablespoon	17.76	Older British recipes
Australian tablespoon	20	Four teaspoons, not three

The tablespoon is the other trap: an Australian tablespoon is 20 millilitres, or four teaspoons, not three. When a recipe gives only cups and spoons and you care about the outcome, find a version that lists grams, or convert once with a table like the one above and write the weights on the recipe card.

The ounce trap: weight against volume

An ounce of weight and a fluid ounce of volume are different units that share a name. One avoirdupois ounce is 28.35 grams. One US fluid ounce is 29.57 millilitres. They are nearly equal for water, which is exactly why the confusion survives, and they are not equal at all for flour, oil or honey.

British recipes make it worse by using imperial fluid ounces (28.41 mL) while selling butter by weight in 250 g blocks. If a recipe says "8 oz chocolate", that is weight. If it says "8 fl oz milk", that is volume. Nothing in the abbreviation "oz" tells you which, so read the ingredient.

Butter, in the units it is actually sold in

Butter packaging by market
Market	Typical pack	Notes
United States	113 g stick (½ cup, 8 tablespoons); 454 g box of four	"One stick" is 113 g; "one cup" is 227 g.
UK and Ireland	250 g block	Printed with 10 g or 25 g markings and often with tablespoon equivalents.
Continental Europe	250 g block, sometimes 200 g	No cup markings; European recipes use weight.
Australia	250 g block	A tablespoon of butter is 20 g, not the US 14 g.

If a recipe calls for "one stick" and you are outside the US, use 113 g. If it calls for "one cup of butter", that is 227 g, which is two sticks or just under a 250 g block.

Oven temperatures: four scales, one dial

Ovens are the other place where unit confusion ruins dinner, because Celsius, Fahrenheit, gas marks and fan settings all describe the same thing differently.

Common oven settings, with fan equivalents
Gas mark	°C (conventional)	°F	°C (fan)	Typical use
1	140	275	120	Meringue, slow drying
2	150	300	130	Rich fruit cake
3	165	325	145	Biscuits, shortbread
4	180	350	160	Most cakes and sponges
5	190	375	170	Pastry, Yorkshire puddings
6	200	400	180	Roast vegetables, bread
7	220	425	200	Pizza, roast potatoes
8	230	450	210	Fast browning

The exact Celsius equivalents are not round numbers — 350 °F is 176.7 °C — which is why recipe writers round. When converting, round to the nearest 5 °C and expect to adjust by a few degrees for your own oven; most domestic ovens are 10 to 15 degrees off their dial anyway. An oven thermometer is a better investment than a more precise conversion.

Scaling a recipe without breaking it

Doubling a recipe is not quite doubling every number. Salt, leavening agents, strong spices, alcohol and setting agents such as gelatine do not scale linearly — doubling the baking powder can leave a metallic taste, and doubling the gelatine turns a delicate panna cotta into rubber. A practical rule is to scale those by about three-quarters of the linear factor the first time and taste or check the set before committing.

Eggs scale awkwardly too. A recipe calling for 1.5 eggs is a sign that the original was scaled by a computer rather than a cook: beat an egg, weigh it, and use the fraction by weight. One large egg is about 50 g without the shell, split roughly 30 g white to 20 g yolk.

Pan size is the factor most often forgotten. Doubling a recipe in the same tin overflows; moving to a tin twice the area but the same depth changes the baking time and the crumb. If the batter depth changes, expect the time to change with it.

Frequently asked questions

How many grams are in a cup of flour?

About 120 to 125 grams for plain or all-purpose flour when spooned into the cup and levelled. Scooping straight from the bag compacts the flour and can push the same cup to 140 or 150 grams, which is enough to change a cake's texture.

Is a US cup the same as a metric cup?

No. A US cup is 236.6 millilitres; a metric cup is 250 millilitres. The gap is 5.7 percent, which is small in soup and significant in pastry.

How much is a stick of butter?

113 grams, or half a US cup, or eight tablespoons. Outside the US, butter is usually sold in 250 g blocks, so a stick is just under half a block.

What is 180 °C in a fan oven?

Set a fan oven to about 160 °C. Fan ovens move hot air, so they brown and set food faster than a conventional oven at the same dial reading; the usual adjustment is 20 °C lower.

Why does my conversion give a different result from the recipe?

Almost always because the recipe's cup was a different size, or because the ingredient was measured by volume in one place and weight in another. Check the cup convention first, then check whether the ounce in the recipe is a weight ounce or a fluid ounce.

Sources

USDA FoodData Central — densities and serving weights for flour, sugar, fats and grains.
NIST Handbook 44, Appendix C — US customary units of volume used in trade.
King Arthur Baking, ingredient weight chart — commonly used cup weights for baking.
UK Weights and Measures Act 1985 and the Metrication Board guidance — imperial fluid ounce and cup definitions.