SIM cards come in three different sizes, the size you require depends on your phone.
The three sizes are Standard, Micro, and Nano.
Most current and later generation major smartphones (eg. iPhone 5, Galaxy S6, Xperia Z3, LG G5 and later) will use a NanoSIM card. These are the smallest of the three sizes.
Many slightly older generations of devices, and many of the mid-range smartphones (eg. Galaxy S4/S5/J1/J3, Note 4, iPhone 4, LG G4) will use a MicroSIM card. This is the middle sized.
Finally there is the Standard SIM card, this is more common amongst earlier smartphones and also basic phones (eg. Telstra Flip/T96/Easy Call/Cruise, iPhone 3G/3GS, Galaxy S2). These are the largest of the three SIM card sizes.
What do the three SIM sizes look like:
These are the three SIM sizes, and will give you an idea of the difference in size between the three. You may also now find that if you get a new SIM that it has multiple sizes in one. Most new SIM cards are Multi-fit SIM cards and can be used for all three sizes, by popping out the size for your device. It is sometimes a good idea to keep the other pieces you pop out as you may use them in the future if you need to use your sim card in an alternative device.
What happens if I need a new SIM card:
There are a whole range of reasons why you might need a new SIM card, it could be because you got a new phone which needs a new size, or even as a part of troubleshooting if an issue arises, but don't worry the process pretty simple.The quickest way is to visit your local Telstra Store or dealer and request a SIM Replacement. It is free, and your local store assistant should be able to get the order sorted for you in a matter of minutes. Just make sure you take some ID with you so they can confirm you're the owner of the service.
If you are unable to get to a Telstra Store or you live in an area without one, no problems, you can also get a SIM Replacement sent out via the mail by calling 132200 and say “SIM Replacement” and our team will send you a replacement sim card by mail. We’ll also give you the option to suspend your service until the new SIM is received – just in case someone tries to use it.
Is there anything else I need to know?
You should not cut a SIM card down in size, if you do so and it causes damage to your device it may cause your device warranty to be voided. It may also cause the sim card itself to fail.