Mobile phone SIM card sizes

Most modern smartphones use microSIM cards – but what are they?!

Old style “normal” phones (like your trusty old Nokia phone that lasted a week between charges) use a mini SIM card.  They are the SIM cards with the most plastic around the gold contacts.  Many Blackberry handsets use these, too.

Many current smartphones – like the Samsung Galaxy S3 and the iPhone 4 – use the micro SIM : that’s the size with a little bit of plastic around the gold contacts.

Rare at the moment, but the smallest size is the nano SIM – the iPhone 5 uses that: it’s the one with pretty much no plastic around the gold contacts.

Comparison of different SIM sizes


The gold contacts in each case are all exactly the same.  If you feel brave. you can cut a mini SIM to size so that you can use it as a micro SIM – but most people prefer to ask their mobile network to send them a new one.

Cutting to size to make smaller

To cut a mini SIM to micro size, you can use a cutter like this – about £3 from Amazon: it looks like a stapler and just punches the gold contacts out of the oversized plastic.

Making bigger

If you have a SIM that’s smaller than you need, you can just get a plastic holder that will make your SIM bigger again.  They’re about £2 from Amazon, something like this.