Your phone’s user guide will tell you which size to use, and how to insert it. Our device guides can also give you more advice. Fortunately, we now use multi-SIMs, which allow you to pop out the size you need for your device.
Find out how to order a replacement SIM for your device.
If you’re using an Apple Watch, this has a built-in SIM called an eSIM, so you won’t need to insert a physical SIM card. However, if you’ve received a replacement device, you’ll still need to activate the new eSIM.