Common Questions About Converting Cooking Measurements

Updated on June 14, 2026

Why Do US and Metric Recipes Feel Like They're Speaking Different Languages?

If you've ever pulled up a BBC recipe and immediately hit a wall of grams and millilitres when you're standing in a kitchen stocked with measuring cups and tablespoons, you're not alone. The US stubbornly uses volume measurements for almost everything—including solids like flour and sugar—while most of the rest of the world measures by weight. Neither system is wrong, but the gap between them causes genuine confusion, and a bad conversion can ruin a whole batch of cookies.

The questions below are the ones I get most often. Let's actually answer them properly.

Q: How Many Grams Is One Cup of Flour?

This is the single most Googled cooking conversion, and here's why it's tricky: one cup does not equal one fixed weight of flour. It depends entirely on how the flour is measured.

  • Spooned and levelled (the correct US method): approximately 120–125 g per cup of all-purpose flour
  • Scooped directly from the bag: anywhere from 150–180 g, because the flour compacts
  • Sifted first, then measured: closer to 100–110 g

This isn't a small difference. A recipe calling for 2 cups of flour could mean anywhere between 200 g and 360 g depending on technique. When you're converting a US recipe to grams, assume the recipe author used the spooned-and-levelled method and go with 120 g per cup as your default. If the baked result comes out too dense or too flat, that's your first variable to adjust.

Other common cup-to-gram conversions worth knowing:

  • Granulated sugar: 1 cup = 200 g
  • Brown sugar (packed): 1 cup = 220 g
  • Powdered/icing sugar: 1 cup = 120 g (it's airy)
  • Rolled oats: 1 cup = 90 g
  • Cocoa powder: 1 cup = 85–90 g

Q: What Exactly Is a "Stick of Butter" and How Do I Convert It?

American recipes throw around "sticks of butter" like everyone grew up with them, which is baffling if you live somewhere butter comes in a 250 g block.

Here's the breakdown: one US stick of butter = 113 g = ½ cup = 8 tablespoons. Most US butter sticks have measurement markings printed right on the wrapper, so if you ever buy US butter you can just cut to the line. But when you're working with a European block, here's what the common amounts look like:

  • ½ stick = 57 g ≈ 4 tablespoons
  • 1 stick = 113 g ≈ ¼ of a 500 g block
  • 2 sticks = 227 g ≈ just under half a 500 g block

One practical tip: keep a kitchen scale nearby when working with butter. Trying to measure 57 g of cold butter in a measuring cup involves a lot of cursing. Weight is just easier.

Q: Cups to Millilitres — What's the Actual Number?

This one at least has a clean answer. A US cup = 236.6 ml, which most people round to 240 ml for practical cooking purposes. The difference of 3–4 ml per cup won't affect any recipe.

But there's a catch: not all "cups" are the same cup.

  • US legal cup (used on nutrition labels): 240 ml exactly
  • US customary cup (used in recipes): 236.6 ml
  • Metric cup (Australia, Canada sometimes): 250 ml
  • Imperial cup (old UK, rarely used now): 284 ml

Australian recipes are the sneaky ones—their cup is 250 ml, which means their tablespoon is also different (20 ml vs. the US 15 ml). If you're making an Australian recipe and the sauce seems thinner than expected, check whether you're using the right tablespoon size.

Q: I See Both Celsius and Fahrenheit in Oven Temperatures. How Do I Convert?

The formula you'll find everywhere is: °F = (°C × 9/5) + 32. Going the other way: °C = (°F − 32) × 5/9.

But honestly, for baking you don't need to do the math every time. Here are the temperatures that come up constantly:

  • 150°C = 300°F — low and slow, think meringues and cheesecakes
  • 170°C = 340°F — gentle baking, custards
  • 180°C = 356°F — the workhorse temperature, most cakes and cookies
  • 190°C = 375°F — slightly higher, brownies and muffins
  • 200°C = 392°F — roasted vegetables, pastry
  • 220°C = 428°F — high heat, pizza, bread
  • 230°C = 450°F — very high, searing roasts initially

Also worth noting: fan-assisted (convection) ovens run hotter. If a recipe was written for a conventional oven and you have a fan oven, drop the temperature by about 15–20°C (25–30°F) and check a few minutes early.

Q: What About Teaspoons and Tablespoons? Are Those the Same Everywhere?

Pretty much, with one important exception already mentioned above (Australia's 20 ml tablespoon). In US, UK, and Canadian recipes:

  • 1 teaspoon = 5 ml
  • 1 tablespoon = 15 ml = 3 teaspoons

Where people go wrong is with leavening agents. If a recipe calls for 1 teaspoon of baking powder and you accidentally use a tablespoon (easy to do when you're tired), that's three times as much. Your cake will rise dramatically in the oven and then collapse. Baking soda is even more potent—too much and you'll taste it. Always double-check teaspoon vs. tablespoon abbreviations: tsp (or t) vs. tbsp (or T or Tbl).

Q: Fluid Ounces vs. Regular Ounces — Why Are There Two?

This confuses even experienced cooks. They are completely different units that happen to share a name.

Fluid ounces (fl oz) measure volume. 1 US fl oz = 29.57 ml. You'll see this on milk cartons, juice bottles, and in recipes for liquids.

Ounces (oz) measure weight/mass. 1 oz = 28.35 g. Used for butter, chocolate, cheese.

Water is the one exception where they're nearly interchangeable because 1 fl oz of water weighs almost exactly 1 oz. But try that logic with honey (denser) or vegetable oil (lighter) and you'll get different results. When a recipe says "4 oz of cream cheese," it means weight. When it says "4 fl oz of cream," it means volume. Context usually makes it clear, but if in doubt, look at whether you'd logically measure that ingredient in a liquid measuring cup or on a scale.

Q: Is There a Shortcut for Converting Recipes at Scale?

Yes — and it's simpler than people think. Once you've converted a recipe to grams and millilitres, scaling is just multiplication. Want to make 1.5x the recipe? Multiply every ingredient by 1.5. Want half? Multiply by 0.5.

Volume measurements don't scale as cleanly because measuring cups come in fixed sizes. You end up trying to measure ⅜ cup of something, which doesn't exist on a measuring cup. With weight, ⅜ of 200 g is just 75 g — easy.

The one thing that doesn't scale linearly is cooking time. A cake batter doubled in quantity doesn't take twice as long to bake — usually 25–35% longer is closer. Use a toothpick test or probe thermometer rather than relying purely on time.

Q: What's the Easiest Way to Handle These Conversions in Real Life?

A few honest suggestions:

  1. Buy a kitchen scale. A basic digital scale costs under $15 and eliminates 90% of these questions. Weight doesn't lie; volume does.
  2. Keep a conversion cheat sheet on your fridge. The flour, sugar, and butter conversions come up constantly. Write them down once.
  3. Bookmark a reliable converter. Not all conversion tools are accurate — some use rounded numbers that stack up badly across a whole recipe. Find one that's ingredient-specific for baking.
  4. When in doubt, go with the original recipe's system. If a recipe was developed in grams, convert everything to grams and don't mix systems mid-recipe. Hybrid measurement approaches are where mistakes happen.

Cooking conversions feel overwhelming at first, but the same questions come up again and again. Once you have flour, butter, cups-to-ml, and oven temperatures memorised — or on a Post-it note somewhere visible — you can tackle any recipe from any country without breaking a sweat.