Convert Cooking Measurements Without Ruining Your Recipe (Cups, Tablespoons, mL, Grams)

A recipe says “1 cup of flour”. You measure it carefully and the muffins come out dense, gummy, and 20% heavier than the photo. You did not do anything wrong — you just used a cup of flour. Volume is one of the worst possible ways to measure dry ingredients, and the moment a recipe crosses a national border the unit itself stops meaning the same thing.

This guide covers the unit definitions you actually need to know to convert recipes between US, UK, and Australian conventions, the gram weights that professionals use instead of cups, and the small habits that turn a translated recipe into the same dish the original author meant to bake.

Why a cup is not a cup

There are at least four cups in everyday recipe writing, and they are not the same volume.

• US customary cup — the cup used in nearly every American recipe website, cookbook, and TV show. Defined as 8 US fluid ounces, which works out to 236.5882 mL.
• US legal (FDA labeling) cup — the cup used on US Nutrition Facts panels. Defined by 21 CFR 101.9 as exactly 240 mL, intentionally rounded to a clean metric number for labeling. This is the cup behind “serving size: 1 cup (240 mL)” on a milk carton, but it is not the cup in a recipe.
• Imperial / UK cup — historically defined as 10 imperial fluid ounces, or 284.131 mL. Modern UK home cooking has largely abandoned the cup in favour of grams and millilitres, but cups still appear in older British cookbooks and they are 20% larger than the US cup.
• Metric cup (Australia, New Zealand, parts of Canada) — defined as exactly 250 mL under AS 1325 and the equivalent NZ standards. Used in essentially every modern Australian recipe.

The spread is real. A “cup” can mean anywhere from 236.6 mL to 284.1 mL depending on whose recipe you are following. For most savoury cooking the difference is forgiving; for baking it can sink a cake.

Tablespoons and teaspoons: the Australian outlier

Spoon measures look standardised but are not. Three conventions are in use:

• US tablespoon = exactly 1/2 US fluid ounce = 14.787 mL. The teaspoon is one-third of that: 4.929 mL.
• UK / European metric tablespoon = 15 mL by convention; teaspoon = 5 mL. Functionally identical to the US spoons for any practical recipe.
• Australian tablespoon = 20 mL. The teaspoon stays at 5 mL. This is the trap. An Australian recipe that calls for “1 tbsp baking powder” means a third more leavening than an American or European recipe with the same words.

For small quantities the spoon delta is benign — a 5 mL versus 4.93 mL teaspoon of vanilla extract makes no measurable difference. For chemical leaveners (baking soda, baking powder), salt in bread doughs, and concentrated spices, the Australian 20 mL tablespoon is the single most common cause of failed transcribed recipes.

Why volume measurement is unreliable for dry ingredients

A cup of all-purpose flour can weigh anywhere from about 120 to 150 grams depending on how it is scooped. The major published references disagree by design:

• King Arthur Baking specifies 120 g per cup of all-purpose flour, measured by their fluff-and-spoon method.
• USDA FoodData Central lists all-purpose enriched flour at roughly 125 g per cup.
• Cook’s Illustrated / America’s Test Kitchen uses 142 g per cup, on the “dip and sweep” assumption.
• A casually scooped, unsifted, packed cup commonly hits 150 g or more.

The difference between 120 g and 150 g per cup is 25%. A bread recipe that calls for 4 cups of flour and is converted wrong is off by 120 grams of flour — easily the difference between a tender loaf and a brick. Brown sugar is worse: packed versus loose, the same cup can hold 200 g or 145 g.

This is why every professional bakery and every modern recipe testing kitchen weighs ingredients. It is also why the better new cookbooks list weights alongside volumes, and why the gram column is the one to trust.

Ingredient density reference

The following table is the practical short list — the ingredients that show up in nearly every baking recipe, with the weight per US customary cup that the major references converge on. Where two conventions exist, both are listed.

The two conventions for flour — 120 g/cup (KAB) versus 142 g/cup (ATK) — both have credible kitchens behind them, but the recipe author’s convention is the one that matters. Recipes from King Arthur, Bon Appétit, NYT Cooking, and most newer American cookbooks assume 120 g/cup. Older American cookbooks and many Cook’s Illustrated recipes assume ~140 g/cup. If the recipe gives a gram value, use the gram value.

Cup volumes by region

For converting volume-only recipes between markets, this table is the one to bookmark.

The Japanese rice-cooker cup is 180 mL, and that is the cup the line on the rice-cooker bowl is calibrated for. American-cup users routinely overfill rice cookers by about 30% by ignoring this.

Oven temperatures: the conversion that has to be exact

Oven temperature conversion is one of the few places where the exact formula matters. Fahrenheit and Celsius have an offset as well as a slope:

°C = (°F − 32) × 5 ⁄ 9   and   °F = °C × 9 ⁄ 5 + 32

Common baking temperatures, rounded to the nearest 5 °C the way most European ovens are marked:

For convection / fan ovens, drop the conventional temperature by 20 °C (or about 25 °F) and start checking 10–15% earlier on time. This is a manufacturer convention rather than a thermodynamic one — fan-assisted ovens move heat faster but burn delicate surfaces if run at the same setpoint.

Worked example: porting a US chocolate-chip cookie recipe to grams for a European bake

A standard American cookie recipe reads:

• 2¼ cups all-purpose flour
• 1 tsp baking soda
• 1 tsp salt
• 1 cup (2 sticks) butter, softened
• ¾ cup granulated sugar
• ¾ cup packed light brown sugar
• 2 large eggs
• 1 tsp vanilla extract
• 2 cups chocolate chips
• Bake at 375 °F for 9–11 minutes

Converted with the King Arthur 120 g/cup convention for flour and the table above for the rest:

• 2.25 cups flour × 120 g = 270 g
• 1 tsp baking soda = 5 mL ≈ 4 g
• 1 tsp fine sea salt = 5 mL ≈ 6 g
• 1 cup butter = 227 g (two US sticks; in Europe one 250 g block plus two slices off, or 227 g exact)
• 0.75 cup granulated sugar × 200 g = 150 g
• 0.75 cup packed brown sugar × 213 g = 160 g
• 2 large US eggs ≈ 100 g shelled (about 50 g each)
• 1 tsp vanilla = 5 mL
• 2 cups chocolate chips ≈ 340 g (chips: ~170 g/cup)
• Oven: 375 °F → 190 °C (or 170 °C fan)

Two regional traps in this recipe alone. First, an Australian cook reading the converted version and using a 20 mL tablespoon would not be tripped (no tablespoons here), but if the recipe had called for “1 tbsp vanilla”, the Australian version would be a third stronger than the American original. Second, a UK cook with self-raising flour will have to either substitute plain flour and add the soda, or omit the chemical leavener entirely. Substituting self-raising flour without adjustment is a classic transcription failure.

Common mistakes that ruin transcribed recipes

• Assuming “cup” means the same thing everywhere.Always check the recipe’s country of origin. US 236.6 mL, Australian 250 mL, and historic UK 284 mL are not interchangeable.
• Confusing the FDA labeling cup (240 mL) with the recipe cup (236.6 mL). The 240 mL number on the back of a milk carton is for nutrition labelling, not for recipe writing. The 1.4% difference is meaningless in cooking but regularly trips up calculator authors and meal-prep apps.
• Treating an Australian tablespoon as 15 mL. It is 20 mL. Multiplying spoons of leavener through the conversion blindly will over-leaven a cake by 33%.
• Measuring flour by dipping the cup into the bag. Dipping packs the flour and adds 15–20 g per cup over the spoon-and-sweep method. Recipes assume the lighter measurement unless they say otherwise.
• Forgetting to specify packed brown sugar.Packed and loose brown sugar differ by nearly 50% by weight in the same volume. American recipes default to packed unless they say “loosely packed”.
• Using volume measures for honey, molasses, or peanut butter. These cling to measuring cups and a stated volume can be off by 10% on transfer alone. Weigh sticky ingredients into the bowl by tare.
• Translating a baking recipe between systems but not the eggs. A US large egg is about 50 g shelled; a UK large egg is about 63 g shelled; an Australian extra-large is about 60 g. For a cake that uses 4 eggs, that is a 50 g difference in egg mass — meaningful enough to change crumb structure.
• Rounding oven temperature to the nearest 25 °C. 375 °F is 190 °C, not 200 °C. The 10 °C error matters at short bake times. Use the formula or the table.

The shortcut: weigh everything

A digital kitchen scale that reads to 1 g costs about US$15 and removes every unit-conversion problem in this article. Set a bowl on the scale, tare to zero, add an ingredient until the scale reads the gram value the recipe gives, repeat. There are no cups, no tablespoons, no scoops to wash, and no ambiguity about whose convention you used.

The volume-to-weight tables exist because most home recipes still read in cups and spoons. The right move is not to memorise every density — it is to convert the recipe once, in writing, into grams, and then bake from the gram version forever after. Modern recipe sites that publish both volume and weight have done that step for you. Trust the gram column.