Tablespoon to teaspoon

Three teaspoons make a tablespoon almost everywhere — in the US, the UK and under the metric convention. Australia is the exception: its tablespoon is 20 ml, so it takes four teaspoons.

The ratio holds even though the absolute sizes do not. A US tablespoon is about 14.8 ml, a metric one exactly 15, and a UK one is conventionally treated as 15 too — small enough differences that no recipe notices. The Australian 20 ml tablespoon is the one that bites, because a recipe written there and followed elsewhere leaves you a third short on anything measured in tablespoons. The other habit worth having: a level spoon means levelled off with a knife, and a heaped one holds roughly twice as much, which matters for baking powder and yeast where the margin is small.