Recipe conversion goes wrong more often than almost any other everyday calculation, and the reason is not arithmetic. It is that a cup is a measure of volume while a gram is a measure of weight, and the relationship between them is different for every ingredient. There is no single “cups to grams” number. This guide covers the conversions that actually work, and the traps in the ones that do not.
Why a cup of flour and a cup of sugar are not the same
A cup holds the same volume regardless of what you put in it — about 237 ml in the US. But density varies enormously. One US cup of granulated sugar weighs roughly 200 g. The same cup of all-purpose flour weighs about 120 g. Same volume, nearly double the weight.
Worse, flour is compressible. If you scoop directly from the bag with the measuring cup, you compact it, and that same cup can hold 150 g or more — a 25% error before you have done anything else. Bakers therefore specify the “spoon and level” method: spoon flour loosely into the cup and level the top with a straight edge.
If a recipe gives weights, use weights. A £10 kitchen scale eliminates this entire category of error and is the single biggest improvement most home bakers can make.
Common ingredients, per US cup
| Ingredient | 1 cup ≈ |
|---|---|
| Water | 237 g |
| Milk | 245 g |
| All-purpose flour (spooned & levelled) | 120–125 g |
| Bread flour | 130 g |
| Cake flour | 115 g |
| Granulated sugar | 200 g |
| Brown sugar (packed) | 215 g |
| Powdered / icing sugar | 120 g |
| Butter | 227 g |
| Vegetable oil | 218 g |
| Honey | 340 g |
| Rolled oats | 90 g |
| Rice (uncooked, long grain) | 185 g |
| Cocoa powder | 85 g |
| Chocolate chips | 170 g |
| Chopped nuts | 120 g |
Treat these as good approximations rather than exact figures — published values differ by a few grams depending on the source and on how the ingredient was measured. For anything where precision matters, the cooking measurements converter accounts for ingredient density rather than applying one blanket ratio.
Not all cups are the same size either
This catches people following recipes from other countries.
| Cup | Volume | Used in |
|---|---|---|
| US customary cup | 236.6 ml | United States |
| US legal cup | 240 ml | US nutrition labelling |
| Metric cup | 250 ml | Australia, NZ, Canada |
| Imperial cup (legacy) | 284 ml | Older UK recipes |
An Australian cup is about 6% larger than a US cup. That is usually survivable in a stew and fatal in a cake.
The Australian tablespoon trap
The worst offender in the whole system. A tablespoon is 15 ml almost everywhere — but in Australia it is 20 ml, equal to four teaspoons rather than three. If an Australian recipe calls for three tablespoons of baking powder and you measure US tablespoons, you are 15 ml short.
| Spoon | Volume |
|---|---|
| US teaspoon | 4.93 ml (call it 5) |
| US tablespoon | 14.79 ml (call it 15) |
| Metric tablespoon (UK, most of EU) | 15 ml |
| Australian tablespoon | 20 ml |
Volume conversions that are actually reliable
These hold regardless of ingredient, because they are volume-to-volume:
- 3 teaspoons = 1 tablespoon
- 2 tablespoons = 1 fluid ounce
- 4 tablespoons = ¼ cup
- 5⅓ tablespoons = ⅓ cup
- 8 tablespoons = ½ cup
- 16 tablespoons = 1 cup
- 2 cups = 1 pint
- 4 cups = 1 quart
- 16 cups = 1 gallon
One caution on fluid ounces: a US fluid ounce is 29.57 ml but an imperial fluid ounce is 28.41 ml, and a US pint is 16 fl oz while an imperial pint is 20. A UK pint is roughly 20% larger than a US pint. The volume converter distinguishes the two systems.
Butter
US recipes measure butter in sticks, which do not exist elsewhere.
- 1 stick = ½ cup = 8 tablespoons = 113 g = 4 oz
- 2 sticks = 1 cup = 227 g
- 4 sticks = 1 pound = 454 g
Oven temperatures
Three systems are in active use, and gas marks map to neither cleanly.
| Fahrenheit | Celsius | Fan / convection | Gas mark | Description |
|---|---|---|---|---|
| 275°F | 140°C | 120°C | 1 | Very cool |
| 300°F | 150°C | 130°C | 2 | Cool |
| 325°F | 160°C | 140°C | 3 | Warm |
| 350°F | 180°C | 160°C | 4 | Moderate |
| 375°F | 190°C | 170°C | 5 | Moderately hot |
| 400°F | 200°C | 180°C | 6 | Hot |
| 425°F | 220°C | 200°C | 7 | Hot |
| 450°F | 230°C | 210°C | 8 | Very hot |
| 475°F | 240°C | 220°C | 9 | Very hot |
Two things worth knowing. First, the Celsius figures above are the conventional rounded values cooks actually use — 350°F is exactly 176.7°C, but every recipe writes 180°C. Ovens are not accurate to a degree anyway.
Second, a fan (convection) oven runs hotter than its dial suggests because moving air transfers heat faster. The standard adjustment is to reduce the temperature by 20°C, or about 25–30°F, and to expect things to finish slightly early. For an exact conversion at any temperature, use the temperature converter.
Scaling a recipe up or down
Most things scale linearly. Several do not:
- Baking time does not scale. Doubling a cake batter does not double the bake time. Depth matters more than volume — two tins take roughly the original time; one deeper tin takes considerably longer at a slightly lower temperature.
- Salt and spices scale sub-linearly. Start at around 75% of the scaled amount and adjust to taste. This is especially true for chilli, garlic and anything bitter.
- Leavening is sensitive. Baking soda and baking powder scale linearly in principle, but errors compound. Weigh them if you are scaling by an awkward factor.
- Alcohol and extracts scale sub-linearly, since they reduce and concentrate differently in larger batches.
- Pan size changes everything. Scaling by 1.5× and keeping the same tin gives you a raw middle and a burnt top.
Quick reference for the conversions asked most
- 1 cup flour ≈ 120 g · 1 cup sugar ≈ 200 g · 1 cup butter ≈ 227 g
- 1 cup = 240 ml (US legal) · 1 tbsp = 15 ml · 1 tsp = 5 ml
- 1 oz = 28.35 g · 1 lb = 454 g · 1 kg = 2.2 lb
- 350°F = 180°C = gas mark 4
- Fan oven: subtract 20°C from the conventional temperature
And the one rule that removes most of the difficulty: when a recipe offers both, follow the weights.