SIM cards come in three sizes; Standard, Micro and Nano. The simplest way to tell them apart is the amount of plastic surrounding the metal contacts; lots = standard, a little = micro, almost none = nano.
Nowadays most phones accept the smallest size, which is nano. Other connected devices like Mifi dongles or tablets might use the larger sizes.
Triple / Combi-SIMs
Almost all operators now issue ‘combi-SIMs’ which include micro-SIM standard and nano-SIM cards in one piece. Simply pop out the size you need.
Can I cut my SIM card down to size?
We strongly advise against doing this, but yes, it is possible. The SIM contacts in your phone are very, very fragile and using a trimmed SIM will risk damaging them beyond repair.
Can I get a SIM Card adapter?
If you have reduced your SIM down to nano and you need to make it larger for another device then yes, SIM card adapters are readily available. However, you may not need one. In our experience the plastic adaptors that you can get in shops aren’t as secure or convenient as the frame from another multi-SIM. Simply buy a cheap SIM from a pound shop, pop the sim out and use the left over frame with your main SIM.