Unit conversion
Cooking measurement converter
A cup of flour and a cup of sugar weigh completely different amounts, so volume-to-weight conversion needs to know what is in the cup. Pick the ingredient and it will.
Converted to Fahrenheit and gas mark below.
Everything this amount equals
Oven temperature
The cup problem
A cup measures volume, but baking is chemistry and chemistry runs on mass. Flour is the worst offender: scoop it straight from the bag and you compact it, ending up with as much as 150 g in a cup. Spoon it in loosely and level it off and you get about 120 g. That 25% swing is the difference between a tender cake and a dry one.
Sugar barely compacts, so a cup of granulated sugar is reliably close to 200 g. Brown sugar is packed by definition, which is why recipes say “firmly packed” — an unpacked cup can be 40% lighter.
Cups are not one size either
| Cup | Volume | Where |
|---|---|---|
| US legal cup | 240 ml | US nutrition labelling, most modern recipes |
| US customary cup | 236.6 ml | Older US recipes, 8 US fl oz exactly |
| Metric cup | 250 ml | Australia, New Zealand, much of Europe |
| UK cup | 284 ml | Older British recipes, half an imperial pint |
The gap between a US and a UK cup is nearly 20%. In a cake that is the difference between working and not. Australian tablespoons compound this: they hold 20 ml against 15 ml elsewhere, so a recipe calling for four tablespoons of butter can be out by a third.
Oven temperatures and the fan adjustment
Fan or convection ovens circulate air, which transfers heat faster than still air at the same temperature. The standard adjustment is to drop the set temperature by about 20 °C, or 25–30 °F, and expect the food to finish slightly sooner.
Gas marks follow their own scale, roughly 14 °C per mark from mark 1 at 140 °C. Mark 4, at 180 °C, is the workhorse setting for most baking. Note that domestic ovens are frequently 10–20 °C out from their dial; an oven thermometer is the cheapest reliability upgrade in most kitchens.
When precision actually matters
Volume measures are fine for soup, stew and anything you taste as you go. They start to matter for cakes and biscuits, and they matter enormously for bread and pastry, where the ratio of flour to water sets the entire structure. Bakers quote hydration as a percentage of flour weight for exactly this reason — a formula in percentages scales to any batch size and cannot be thrown off by how someone filled a cup.
A digital scale costs less than a cake tin and removes the whole problem. Weighing also means fewer washing-up items, since ingredients can be added to one bowl on the scale with a tare between each.
Common questions
How many grams is a cup of flour?
About 120 g for plain or all-purpose flour, spooned into the cup and levelled. Scooping directly from the bag compacts it and can push the same cup to 145–150 g, which is the single biggest source of inconsistency in home baking. Bread flour runs slightly heavier at around 127 g.
How many tablespoons are in a cup?
Sixteen in the US system, where a tablespoon is about 14.8 ml. Australia is the exception with 20 ml tablespoons, giving roughly 12.5 to a metric cup. When a recipe’s origin is unclear, the tablespoon size is worth checking before anything else.
What is 180°C in Fahrenheit and gas mark?
350°F and gas mark 4. That is the default temperature for a very large share of baking recipes. For a fan oven, set it to about 160°C instead.
Why do different sources give different gram conversions?
Because they measured differently. King Arthur uses 120 g per cup of flour, some European sources use 125 g, and older American cookbooks assume a scooped cup nearer 140 g. None is wrong, they just describe different filling methods. Pick one source and stay consistent within a recipe.