We all know that knitting needles come in different sizes – the size you use depends on your project and the yarn you’ve got – but did you know that needle sizing varies around the world?

In the USA, needles are given a number to denote their size – the smaller the size, the lower the number. Elsewhere, needles have metric measurements – for example, 3.5mm, 6mm or 10mm. These indicate the diameter of the needle. To confuse things slightly, the UK and Canada once used a different sizing system (sometimes known as ‘imperial’ sizing). This system also used numbers to denote needle size but with the higher numbers indicating the smaller needles – for example a size 11 needle is equivalent to a 3mm one.

So why do you need to know about different needle sizes? Well, you might have found the ideal pattern online but it uses an unfamiliar needle sizing and you need to work out what the equivalent to that size is in the system you are used to. You might also be working from a historic knitting pattern and want to update it with modern needle sizing. Or you might have bought some gorgeous vintage needles and need to find out their equivalent modern-day sizing. 

To help you get to grips with different needles sizes, we’ve made you a handy conversion chart. So if you ever come across a needle size that’s not what you’re used to, simply look it up here. If the size you’re looking for doesn’t have an equivalent needle size in the system you are accustomed to, then you will have to decide whether to go up or down in size – as always, do a tension swatch to be sure you’re using the right needles.