When I moved to the US from England in 2005, I learned that a US gallon is smaller than a UK (or Imperial) gallon: the UK gallon is 160 fluid ounces, whereas the US gallon is only 128 fluid ounces.

And that’s because there are only 16 fluid ounces in a US pint, compared to the 20 that are in an Imperial pint.

But what I hadn’t realised, until today, when I was working on one of our new websites, is that a US fluid ounce is actually equivalent to 1.0408423 Imperial fluid ounces.

I’d always assumed that a fluid ounce is a fluid ounce, but apparently this isn’t the case.

So now you know!