In Australia, a tablespoon is defined as 20mL whereas it is 15mL in nearly all other countries.
I'm interested to know where this comes from, and also what other Australian people do about this because the shops here seem to favour the 15mL variety which isn't a whole lot of use for local recipes.
Best Answer
The following snippet from Wikipedia doesn't fully answer your question, but it's at least suggestive of what might have happened: the UK standardized the tablespoon as a volume measure using its “eating spoon” meaning while Australia used its “serving spoon” meaning.
Here's a list of the definition of the tablespoon measure from older recipe books published in different English-speaking countries. It's a short list, but it does somewhat show that the Australian definition evolved to be generally higher (20ml-25ml) than the UK one (around 18ml), with the South African one on the lower end (12.5ml).
The proliferation of spoons mentioned in the Wikipedia snippet above is still evident in recipe books today. British recipes occasionally still use a “dessertspoon” to mean a 10ml measure. In Dutch recipes (link to a page in Dutch), a 5ml measure is referred to as a “coffeespoon,” while a “teaspoon” refers to a 3ml measure.