In situations where your SIM card is too large for the phone, you’ll need a cutting guide. In this post, you can download a free printable guide.
If you have a contract and upgrade your phone, you could end up with a model that uses a smaller SIM and that’s why you might want to cut the plastic down in size.
Or you might buy an unlocked phone and realise the SIM you want to insert into it is too big.
The point is that you probably want to keep using the same business mobile phone number in different phones. A PAC code request or SIM swap may well be the answer, but if it isn’t, the PDF download furthur down this page may help.
First, a word on the different sizes.
The 3 Sizes
The SIMs come in three different sizes: Standard, Micro and Nano.
The standard size is sometimes referred to as a Mini SIM, which seems odd given it is the largest of its type.
Mini SIM (2FF)
- Length: 25.00 mm
- Width: 15.00 mm
- Height: 0.76 mm
Micro SIM (3FF)
- Length: 15.00 mm
- Width: 12.00 mm
- Height: 0.76 mm
Nano SIM (4FF)
- Length: 12.30 mm
- Width: 8.80 mm
- Height: 0.67 mm
Hack Your SIM Size in 5 Steps
The following guide is meant for anyone wanting to reduce the size of their standard SIM card to a Micro or Nano Size.
It didn’t take me long to cut down a SIM I’d been using as my business contact number.
The iPhone 4S I bought online required a Micro (3FF) size.
I used this guide to put my old SIM in the iPhone 4S. I was laughing and rubbing my hands together.
1) Download and Print PDF
Make sure you print it as 100%.
It is created by GiffGaff but the principle is applicable to any SIM.
2) Fix SIM Securely to Page
To hold the SIM in its place I found it best to use double sided sellotape or some other double side self adhesive.
If you want to try a tiny amount of blu-tack, make sure you press the plastic card firmly down onto the paper.
Don’t try and pull a MacGyver – bubble gum doesn’t work in real life!
3) Use Pencil & Ruler to Draw Guidelines
It’s important to fasten the SIM in place on the paper guide because you’ll need to draw pencil lines on the plastic using a ruler.
4) Use Knife or Scissors to Cut Plastic
Once you have drawn the pencil lines, use a ruler and sharp knife to score lines as a pilot guide.
Alternatively, use a strong pair of scissors (kitchen scissors are good) to cut along the pencil lines.
Be VERY careful not to take off too much, otherwise you SIM will not be a snug fit inside the phone.
5) Use Sandpaper to Finish Edges
When I cut the plastic, I erred on the side of caution by not taking too much off. I finished the edges with sandpaper to file down the plastic.
SIM Cutting Video Guide
There’s a pretty good video guide here if you’d like to watch someone else go through the process first.
It’s bit daunting tampering with the plastic first time because it’s worrying to think of what could go wrong.
Upsizing the SIM
The flaw in this blog post is that it assumes you want to make your SIM smaller.
This is a problem if you decide to abandon Apple and go over to Google Android which means possibly moving up a notch from a Nano SIM to a Micro SIM.
In this case you might have no choice but to request your carrier’s PAC (Porting Authorisation Code) and do a transfer. (You don’t need the PAC code if you’re staying on the same network – you usually just do a SIM swap.)
Pre Cut SIMs
My provider, GiffGaff supply the three different sized SIM cards, so if you upgrade your phone to a model requiring a smaller size, as long as you’re not moving to a different network there’s no need to request the PAC code.
The other thing they do is supply the Micro Sim (3FF) precut and affixed inside the Standard SIM (2FF) in a fashion not dissimilar to Airfix models.
It’s easy to pop the Micro size out of the Standard size outer plastic.
If you want to put it back together, it is easily snaps back together. If it is loose, use super glue.
GiffGaff Help
Keep your number
Ask your current network provider for a PAC code. Learn more here.
Unlock your phone
If your phone is locked to another network, you will need to get it unlocked.
Get support online
We have an army of members and agents, ready to provide you with our super-speedy (24/7/365) online support. It starts here.
Buy a Micro SIM Cutter
If you don’t fancy cutting your precious SIM with a knife and ruler, consider purchasing a dedicated micro SIM cutter. (Affiliate link)
Now, I need to be honest and say I haven’t used one of these myself (at least not yet) so I cannot speak for the results they give.
I’m merely pointing it out as an option for those of us who dare not risk bodging their SIM using the DIY method.
Find out which SIM card your iPhone or iPad uses
Are you an Apple user? I am, and the following link is useful in identifying what sized SIM your device uses.
https://support.apple.com/en-us/HT5554
I hope they continue updating the page with their latest models with information about the SIM size.
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The Mini Sim is actually not the largest of its type, its just the largest currently available.
Previous to the mini sim, sim cards were full sized – the same size as a credit or debit card.
Also some shops will cut sims for you. Carphone Warehouse does it in the UK I believe.
I bought my iPhone on eBay and used the SIM from a previous handset… I had to do it myself for those reasons. I know Giff Gaff (my current provider) now offer various sized SIMs which is great and very helpful.