Why a Tablespoon Isn't the Same Size Everywhere

Same word, three different volumes

A US tablespoon is exactly 14.787 mL. A UK or Australian "metric tablespoon," used in most recipes written in those countries today, is a flat 15 mL. It's a tiny difference — well under 2% — and in a single tablespoon of an ingredient it almost never matters for how a dish turns out.

Where it starts to add up

The gap gets more noticeable with cups: a US cup is 236.588 mL, while an Australian cup is a rounder 250 mL — over 5% larger. Scale a recipe that calls for several cups of flour or liquid, and that 5% difference compounds into a real, noticeable change in a baked good's texture, since baking especially is sensitive to precise ratios between dry and wet ingredients.

Why this exists at all

The US never fully adopted the metric system for everyday cooking, so American recipes still use cups, tablespoons and teaspoons defined by older customary measures. Most other English-speaking countries converted their kitchen measures to round, metric-friendly numbers decades ago, which is why "tablespoon" quietly means something slightly different depending on where the recipe was written.

How to tell which one a recipe is using

There's no universal label, so context is the best clue: a recipe from a US website or cookbook almost always means US customary measures, while one from an Australian, UK or New Zealand source almost always means the rounder metric versions. When a recipe gives both cups and grams for the same ingredient, trust the gram measurement — weight doesn't have this regional ambiguity at all.

Try it yourself

Our Cooking Measurement Converter converts between US customary volumes and milliliters/liters using exact definitions, so you can see precisely how a US measurement compares.