Cooking Measurement Conversions: Cups, Grams, ml & Oven Temps

You find the perfect recipe online, get halfway through, and hit a wall. It calls for "1 cup of flour" and a "350°F" oven — but your measuring jug is marked in millilitres and your oven dial only goes up in Celsius. Or it's the reverse: a British baking blog lists everything in grams and "gas mark 4," and you're standing in an American kitchen holding a set of measuring cups. A simple bake suddenly turns into a maths problem.

Kitchen conversions look trivial until you actually need one, and then a surprising amount of nuance shows up. A "cup" isn't the same size in every country. "One cup of flour" and "one cup of honey" weigh completely different amounts. Oven temperatures don't convert as cleanly as you'd hope. This guide clears all of it up — the exact numbers, the reference tables worth bookmarking, and the two or three ideas that make every future conversion obvious.

The two things that make kitchen conversions tricky

Most people assume converting a recipe is just arithmetic. It mostly is — but two quirks cause almost every mistake, and once you understand them the rest is just reading off a table.

First, volume and weight are not interchangeable. A cup, a tablespoon and a litre all measure volume — how much space something occupies. Grams and ounces measure weight. Converting cups to millilitres uses a fixed number because both sides are volume. But converting cups to grams depends entirely on what you're measuring: a cup of feathers and a cup of lead weigh wildly different amounts, and the same is true of a cup of flour versus a cup of honey. That single fact explains why there's no universal "cups to grams" number.

Second, a "cup" is not one universal size. A US cup is 236.6 ml, a UK cup is 284.1 ml, a metric cup (Australia, New Zealand, much of Europe) is a round 250 ml, and a Japanese cup is 200 ml. So an American recipe and an Australian recipe can both say "1 cup" and quietly mean different amounts.

Keep those two ideas in mind and everything below falls into place.

Volume conversions: cups, tablespoons, teaspoons and millilitres

Within a single system, volume converts cleanly. Here are the US measures most online recipes use, with their millilitre equivalents:

The one ratio worth memorising is that 3 teaspoons make 1 tablespoon — and that holds in every measurement system, even when the absolute sizes differ. If you ever forget whether a recipe means teaspoons or tablespoons, that 3-to-1 relationship is your anchor.

Rather than reach for a calculator mid-recipe, you can convert any of these instantly — and switch between US, UK and metric definitions — with the Volume & Cooking Converter:

Is a cup the same everywhere? US vs UK vs metric

This is the trap that ruins more bakes than any other, because nothing warns you. The recipe just says "1 cup," and you assume your cup is the right one. Here's how the three common systems actually compare:

A UK cup is about 20% larger than a US cup. In a forgiving recipe like soup that's harmless, but in baking — where the ratio of flour to liquid decides whether you get a cake or a brick — it matters. The fix is simple: work out which system the recipe was written for, then convert everything to millilitres or grams, which mean the same thing worldwide.

Cups to grams: the conversion that isn't a single number

Here's where the volume-versus-weight idea earns its keep. Because a cup measures space, not mass, the grams in a cup depend on how dense and how tightly packed the ingredient is. These are reliable averages for a US cup, the figures most online recipes assume:

Notice how far apart these are: a cup of honey weighs nearly four times a cup of rolled oats. That's why any chart claiming a single "1 cup = X grams" answer for everything is simply wrong.

Treat these as good estimates rather than gospel. Flour is the worst offender — scoop it straight from the bag and you can pack in 20% more than if you spoon it in and level it off, which is a real difference in a delicate cake. If precision matters, the honest answer is to stop converting and start weighing.

A quick note on butter "sticks." US recipes often measure butter in sticks, which baffles everyone else. One stick equals 1/2 cup, 8 tablespoons, 113 grams, or 4 ounces — so a recipe calling for "2 sticks" wants 226 g, roughly a standard 250 g block minus a couple of tablespoons.

Oven temperatures: Fahrenheit, Celsius and gas marks

Oven dials are the other daily headache, especially between US recipes (Fahrenheit) and UK or European ones (Celsius or gas marks). These are the standard culinary pairings — slightly rounded from the exact maths for convenience, which is how recipe writers use them:

The exact formula, if you ever need a temperature that isn't on the chart, is °C = (°F − 32) × 5/9 — but for anything between values the Temperature Converter is quicker and shows all three scales at once:

Tin and pan sizes: inches to centimetres

Recipes assume you own the pan they were developed in, and a cake baked in the wrong size can end up raw in the middle or dry and thin. Pan sizes convert as straightforward length, so they're the easy part:

For any size that isn't listed — or to check a tin you already own — the Length Converter gives an exact inches-to-centimetres reading. As a rough rule, if your pan is within about 2 cm of the one specified you can usually proceed; go smaller and you'll need to add a few minutes to the bake and watch it closely.

The kitchen cheat-sheet (worth bookmarking)

If you remember nothing else, these are the conversions that come up again and again:

Best practices for measuring accurately

Getting the conversion right is only half the job — how you measure matters just as much, especially in baking.

• Weigh dry ingredients whenever you can. A scale sidesteps the cup problem completely and is far more consistent than scooping.
• If you must use cups for flour, spoon it into the cup and level the top with a knife. Scooping compacts it and adds up to 20% extra.
• Measure liquids at eye level in a clear jug, reading the bottom of the meniscus (the curved surface), not the top.
• Use proper measuring spoons for small amounts. A "tablespoon" from your cutlery drawer can be off by half.
• Level off dry measuring spoons too — a heaped teaspoon of baking soda or salt can genuinely spoil a recipe.

Common mistakes to avoid

• Assuming every "cup" is the same. Check whether the recipe is US, UK or metric before you measure — the difference is enough to change a bake.
• Using one "cups to grams" number for everything. It only works ingredient by ingredient, because density varies so much.
• Forgetting the fan-oven adjustment. Convection ovens run hotter than the dial; drop about 20°C or one gas mark.
• Converting the whole recipe but not the pan. A batter sized for a 20 cm tin poured into a 15 cm one will overflow or bake unevenly.
• Rounding too aggressively on small quantities. A little slack is fine for a cup of stock; it is not fine for a teaspoon of baking powder.

Frequently asked questions

The bottom line

Kitchen conversions feel fiddly only until the underlying logic clicks: volume and weight aren't the same thing, and a "cup" depends on where the recipe came from. Once those two ideas land, every recipe — American, British or metric — becomes readable. Keep the cheat-sheet handy, lean on a kitchen scale for anything you want exactly right, and let the Volume & Cooking Converter, Temperature Converter and Weight Converter handle the arithmetic so you can get back to the cooking. Everything runs right in your browser, with nothing to install and no sign-up — so the next time a recipe fights you on units, you can settle it in seconds.