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MicroSIMcutter trims oversized SIM cards down to size


October 31, 2012

Mini-, micro-, and nano-SIM cards

Mini-, micro-, and nano-SIM cards

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The SIM cards that fit into those tiny slots in your cell phone and tell your cellular network to whom your calls are to be charged come in four different sizes. With the only real difference between them the amount of excess plastic on which the circuitry is housed, MicroSIMcutter's new SIM card cutter can cut either mini- or micro-SIM cards into the nano-SIM form factor, allowing a user switching phones to recycle their existing card.

All SIM cards have basically the same circuitry – a microcontroller and small amounts of permanent, rewritable, and random access memory. They come in four sizes, ranging from the credit card sized original SIM card to the nano-SIM card, which measures 12.3 mm x 8.8 mm (0.48 in x 0.35 in). Despite the different sizes, they have the same size and pattern of electrodes, and the electronics are buried under the electrodes. The only difference is how much excess plastic is attached to the active part of the card.

The SIM cards are designed to be backwards compatible, so if you have a micro-SIM card but your cellphone takes a mini-SIM card, you can place the micro-SIM card in a mini-SIM adapter, which just adds on the extra plastic.

However, with most cellphone users more likely to upgrade their phones more often than they switch carriers, the most common problem is removing a mini-SIM card from an old phone, and securing a micro- or nano-SIM card for the new replacement phone.

There have been instructions on the Internet for some years describing how the larger SIM cards can be cut down manually, but this requires steady hands, good scissors, and the willingness to risk demolishing your SIM card. Mobile service providers will also offer to copy data from an old SIM to a new, smaller one, but that involves finding time to physically visit a store.

Now there is another option. MicroSIMcutter is importing a Chinese SIM card cutter that can cut either mini- or micro-SIM cards into the nano-SIM form factor. The owner of a new phone can then reuse their old card rather than ordering a new SIM card with a smaller form factor. Their stainless-steel hand cutter, called the Nano SIM Cutter, punches out the shape of a nano-SIM card. A mini-SIM card fits directly into the punch, while a micro-SIM card is placed in a mini-SIM adapter before inserting into the punch to insure proper alignment.

A quick push on a lever, and your need for a nano-SIM card with the correct authentication data is satisfied. Perhaps not an earth-shaking advance, but innovation and good ideas come in all sizes.

Source: MicroSIMcutter

About the Author
Brian Dodson From an early age Brian wanted to become a scientist. He did, earning a Ph.D. in physics and embarking on an R&D career which has recently broken the 40th anniversary. What he didn't expect was that along the way he would become a patent agent, a rocket scientist, a gourmet cook, a biotech entrepreneur, an opera tenor and a science writer. All articles by Brian Dodson

Working on phones on a daily basis, I can tell you first hand that smaller cards are NOT the answer, Micro-SD and the ilk are a pain to get in and out of the phone now!

I don't want to perform micro-surgery!


Looks like the device my wife bought preparing for me buying her an unlocked iPhone 4 [after Apple's recent price cut].

Worked fine. Took the card from her old Samsung feature phone, trimmed it > up and running fine ever since with the iPhone on T-Mobile.

Caution - check prices. These have sold as high as $50+ various online sources. She got her for less than $10.

Ed Campbell

Ed, my Son gave me his iphone 4s, would not work inside the house on T-mobile make a call and watch the bars disappear until the no signal came up, took me 1.5 hours to make a call holding the phone above my head two weeks ago, ended up going outside, consistent non performance, ported my number to my Sons family plan with AT&T I get to make calls inside from home, yes inside three bars all the time, not outside standing in the rain, and T-mobile has the gall to want to charge me $200 for leaving because they can't provide service inside my home

Bill Bennett

Telstra shops have their own simple cutter as would any mobile providers selling iPhone 5s.


I tried one of these Chinese cutters and it did not work properly - cutting the sim incorrectly. Luckily, it was an old sim I couldn't use. Best bet is to get the local ATT or major carrier store to do it.

Joseph Milteer

Old article but I love this little tool! I got one for like 5 dollars, aside from letting me cut my SIM card down to nano size for my iPhone 5c it's made pretty well, it's got heft. Regardless we really need to call it quits at the nano SIM card size (4form factor) but I'm reading about integrated SIM cards now and it's scary :O I just hope microSD cards don't get any smaller or worse, just poof into Apples ready made solution: no expandable memory card slots everything just soldered on in!

Nate Opgenorth
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