How To Convert A Mini-SIM Into A Micro-SIM For iPhone 4

Convert mini-SIM to micro SIM

As you may have known by now, Apple is offering SIM-free and unlocked units of iPhone 3GS and iPhone 4 to customers in UK, France and Canada.

Since these iPhones are not locked to a carrier, users can sign up with any compatible carrier of their choice. 

However, unlike iPhone 3GS, the new iPhone 4 does not support the conventional mini-SIMs. Instead, users will now have to order a new micro-SIM from their carrier.

Micro-SIM for iPhone 4 can be a problem if your carrier does not offer micro-SIM cards yet or takes a long time to process the orders.

There is however an alternate solution. The following how-to guide will take you through a step-by-step process to transform your mini-SIM into a micro-SIM. For the process, you will require a mini-SIM, a marker pen, a ruler, cutter knife and a filing tool. 

Before you proceed, here are a few caveats to note. The chip on the SIM can be delicate and this procedure may permanently damage the circuitry on your mini-SIM. So do remember to proceed with caution. It is a nice idea to try the process out with a secondary SIM before carrying out the procedure on your regular SIM. 

Step 1: The most important part of a SIM is the central circuit that contains information about the subscriber's ICC-ID. The first step is to measure the area around this circuitry based on the size of the micro-SIM. 12mm x 15mm is the standard dimension of a micro-SIM. You may do this with the help of a ruler and a marker pen. 

Important: We would strongly recommend you to wait for your iPhone 4 so that you can confirm the size of the micro-SIM that fits iPhone 4's SIM tray before using this guide.

Convert mini-SIM to micro SIM

Step 2: The mini-SIM needs to be cut along these marked lines. But before you proceed, run a cutter knife a few times over these lines to prominently mark the sections. 

Convert mini-SIM to micro SIM

Step 3: If done correctly, you may now be able to break away the plastic portion of the SIM that is not required. Alternately, use a scissor to cut along these marked lines. 

Convert mini-SIM to micro SIM

Step 4: You are almost done. Use a filing tool to soften the cut edges.

The new micro-SIM for iPhone 4 is ready. You may now insert this SIM into your iPhone for use. If you are buying an unlocked iPhone 4 and are trying out this process then do not forget let us know how it works. 

Note: If you're in UK, you can checkout this link to find out more details about getting the new micro-SIM from your carrier.

[Source and images via JohnBensoniHackintosh]

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  • Benji

    "12cm x 15cm is the standard dimension of a micro-SIM" Think you mean mm 🙂

  • Yup 🙂 Thanks for pointing it out.

  • Spitfire

    God what a pain in the arse all that is, still there must be reasons for it..

  • theone


  • freddieboy217

    According to Steve Jobs at his keynote speech they needed the space for the exrta hardware

  • Spitfire

    Yeah fair enough, still a pain tho for me to buy a phone on pay n go, then have to cut my sim to size, or wait for bloody networks to get them, ah well will get there in the end.

  • Vishnu

    NO its 11mm x 15mm, 1CM= 10mm

  • Munir Algonn

    Check on e-bay, there is special tool to cut mini-sim to micro-sim. all you have to do is insert the mini-sim in the cutter, press it down and you now have a micro-sim.

  • Geosnot

    Shall take a look thanks

  • wolverinemarky

    i wont need this but will pass the information on to my friends who might need it

  • Nobber

    The eBay ones I saw are only available ore order anyway, til after the iPhones release, who wants to wait that long? Was hoping to get a cutter before the 24/6 not after lol

  • superfreak

    Checked out the tool on ebay. Looks very easy to use, and would save a lot of time.

  • superfreak


  • For those who don't have steady hands, here's an alternative:

  • Saikhanbayar

    This works with any GSM carrier's sim card right?

  • kashyap

    they demonstrated using bsnl sim…..means it came from india!!!

  • Jcm800

    forgive my iggnorance, I was led to believe that a micro sim was superior to a regular sim, and this is why Apple are using them now??
    Can any one shed any light on this? Is it just a change in sim size or is there a genuine improvement using a micro sim as opposed to a trimmed to fit regular sim?


    What if I just need a tray to fit the new micro sim in an mini slim slot? I need just the opposite as my ATT phone will come with the new SIM in place. But i would like to use my jailbroken 3GS for tethering still.

  • You need a Micro-SIM adaptor. You can probably buy one on eBay.


    IS IT 11MM OR 12MM

  • RuiiuR

    As I have noticed there seems to be a small difference between sim and microsim. The chip area (golden part) of the sim looks to be slightly bigger than the microsim, so would it be right to assume that the contact parts in the iPhone 4 would be also different? Will then the normal sims work in the new iPhone?

  • Jcm800

    Good point, i'm not convinced that trimming down my regular sim is going to be as good as using a dedicated micro-sim card, i think theres a reason for the gold part to be slightly diff..

  • hahaha such a niece post

  • Rusy Shackleford

    Ok. So I trimmed my simm to work in my IPAD and now I keep getting messages that read, "Matthew Verbin, It's 3:00." What the he!! does that mean?!!

  • Jcm800


  • RuiiuR

    Since people are receiving their IPhone 4's has anybody triend trimming their sim? If so, did it work

  • PLEASE, iPad and iPhone are difference.
    Please careful

  • bomijoa

    I have modified using this way…

  • sunny

    i tried and it didn't

  • marcomaui

    I removed the sim card and reinserted and it did not fix the antenna problem, however I noticed 2 indentation on the SIM card. Please look at pic. Does everybody have these 2 indentation on their SIM card and is there a function associated with it?

  • gazzeg

    Hi all, There are a couple of different sims. Carphone Warehouse use the old type that you can see at the top of this page. as you look at the sim thats been cut further down the page you will see there is a difference between the top normal sim and the one thats been cut.
    I have a Carphone Warehouse contract and have cut two of there sims. These do not work on the Iphone 4. If you have a o2 direct contract and have a sim that looks like the the one thats been cut you will have no problems as I have also tested this on a PAYG sim.

    Please please check your sim before you ut as this cost me £30 to get the two replacement sims I cut.

    Carphone warehouse are not supplying the new micro sims also as O2 are forcing them to put al new contracts directly through them. This means you are knackered if you are with them on contract.

    Hope this helps and saves you all the costly lesson I have done….


  • hsv2049

    Worked for me, on iPhone 4. It is easier if you have a micro-sim to place over your mini-sim to trace around as a template.

  • youdame

    I tried it, as gazzeg said, he/she is correct. The first sim portrayed above (blue) is the old sim with the large golden part. I have that kind of sim. I cropped it down to perfect size with a lot of sandpapering and it fits perfectly into the slot. BUt it still doesn't work.

    I suggest that you take a MICROSIM and compare it to the old sim you have, if the golden contacts are the same size then you are good to go but if the old sim has larger golden contacts then don't do this as it won't work.

  • Karan

    Iphone 4 only supports 3g n 4g sims

    so 2g sims will not work

  • Bart

    I pulled my iPhone4 sim to see if it would work and I touched those gold peices on it. Now I get a message on my phone that says, “Matthew Verbin, It’s 3:00.” Is this some error message ATT uses? What does it mean? Who is Matthew Verbin? I am afraid to call ATT becuz they might void my waranty. HELP!

  • Joe

    You can still get a free sim or micro SIM with £5 free credit from http:/

    Powered by the O2 network in the UK with unlimited internet.

  • Rob

    I sat my normal sim on a microsim and started cutting around it. Caused no problem whatsoever. Needed a few minor adjustments after cutting but works great.

  • I cut down both a Three and an Orange SIM to fit my iPhone4. The Three works fine in the device, the Orange works fine with Gevey SIM.
    I did use a sharp knife (remember to let your dad do it for you if you’re the kind of person that cuts towards yourself) to whittle it down to a perfect shape.

  • Fz

    Its shit, this wont worked out…..
    the size of a micro sim “”circuit”” is smaller than that of mini sim… thus it will never ever work….

  • Nick

    Worked for me, thanks 🙂

  • Phone GEEZER

    I did this for my NOKIA Lumia 710, and had a few issues. HOWEVER, I got them totally cleared up, and my old Micro Sim is now functioning quite well as a MINI Sim. But, since this is for a NOKIA, I have no idea if it would work on an Iphone 4. I did do some easily understood documentation with PICTURES, and they can be seen at:

    • Frank Kahney

      The middle picture has the metal circuitry that looks much larger than the new micro sim. How can this work when they are different sizes?

  • Frank Kahney

    I’ve read elsewhere that some people need to unlock their PIN on their sim. How do you find out if your sim has a PIN lock?
    Also I’ve read some people not being able to access their network. Does the cut down sim work on O2?

  • Thanks for the share
    I’ll try it, I hope I didnt break something