What size SIM card do I need for my phone?

What size SIM card do I need?
(Image credit: Daniel Kaesler / EyeEm)

You've got your new SIM in the post, torn off the wrapping and excitedly poked the old one out of your phone after bending up a paperclip for the task, only to find – horror of horrors – the new SIM doesn't fit. We've all been there. But if you're reading this before ordering yours, you don't have to go through that. You likely found your new SIM on our best SIM only deals, guide right?

This is how to make sure you get the right sized SIM for your phone, first time, so you can enjoy the new connection speed and data right away.

What size SIM cards are there?

SIM cards these days fall into three sizes and these are: Standard, Micro and Nano, descending in size. More on eSIMs below. If you're ordering your SIM only you'll likely find it arrives in a credit card sized piece of plastic out of which can you pop your microchip SIM.

A standard SIM measures 25 x 15mm and was used in phones before 2010 and a few after then.

The Micro SIM stands at 15 x 12 mm and was used in phones from 2010 and you'll still find some phones work with these now.

The Nano SIM, introduced in 2012, measures in at 12.3x 8.8mm and is the most commonly used SIM in phones.

The Combi SIM might be what you get sent by a SIM only provider as it contains all three sizes, and you push out the one that fits your phone. This is ideal as you don't need to know your size prior to this as you can hold it up to the SIM tray and see.

Finally, there is the eSIM, which doesn't use a chip at all instead coming built into the phone already. If you have one of these phones them this article doesn't really apply, but we thought it worth mentioning in case you're unsure. That said all new phones that support eSIM still have a SIM port in case you need it. These include: Apple iPhone 11 Pro, iPhone 11 Pro Max, iPhone 11, iPhone SE (2020), iPhone XS, iPhone XS Max, iPhone XR, Google Pixel 4, Pixel 4 XL, Pixel 3, Pixel 3a and Pixel 3a XL.

Do I need to know my SIM card size?

There are instances where you might not need to worry about your SIM size. This is usually the case when you're buying the phone directly from the network provider. 

So in the case of a contract deal you'll get sent the phone and SIM by the provider. As such they'll send you the right size to suit your handset.

But if you're buying a second-hand phone or changing your contract to SIM only then you'll want to be sure the device and chip pair up correctly.

How do I know my SIM size?

Most phones will come with clear instructions telling you which SIM card size suits the device. Failing that you can always search online for your exact phone model and the information should be there.

Can I use my SIM in a newer phone?

Since the chip of a SIM has remained the same between the Standard and Micro SIM, it's possible to cut the plastic part down to fit. Although we wouldn't recommend this as if you get it wrong you're a bit stuck.

Definitely don't try this when going from Micro SIM to Nano SIM as the chips themselves are different sizes so even cutting the plastic won't help.

You can buy SIM adapters which allow you to upsize a smaller SIM to larger and these are found cheaply online.

But, since most networks send out SIMs for free, we'd always advise ordering the SIM that you need to fit your phone.

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Luke Edwards

Luke is a freelance writer and editor with over two decades of experience covering tech, science and health. Among many others he writes across Future titles covering health tech, software and apps, VPNs, TV, audio, smart home, antivirus, broadband, smartphones, cars and plenty more. He also likes to climb mountains, swim outside and contort his body into silly positions while breathing as calmly as possible.