Your new phone needs a smaller SIM, but your old card doesn't fit? You can cut a SIM card down to micro or nano size yourself, because the chip is about the same size on every SIM. Only the plastic around it changes. But it's risky: one wrong cut and the SIM stops working, and a badly cut card can get stuck in the tray. This guide gives you the exact SIM sizes, shows you how to cut a SIM card step by step, and explains the safer options: a replacement SIM from your carrier, or switching to eSIM.
SIM card sizes: mini, micro and nano
SIM sizes are set by ETSI, the European standards body behind the SIM card specification (ETSI TS 102 221):
- Mini SIM (2FF), often called "standard SIM": 25 × 15 mm.
- Micro SIM (3FF): 15 × 12 mm.
- Nano SIM (4FF): 12.3 × 8.8 mm, and only 0.67 mm thick (ETSI).
The first SIM cards were the size of a credit card (full-size, or 1FF). Recent phones use a nano SIM, an eSIM, or both. One detail matters if you cut: the mini and micro SIM are as thick as a bank card, while the nano SIM is thinner. So a micro SIM cut down to nano size is still slightly thicker than a real nano SIM.
Not sure which SIM your phone takes? Check the phone's spec page or the SIM tray. Some phones don't take a physical SIM at all: iPhone 14 and later models bought in the United States have no SIM tray (Apple), and the iPhone Air doesn't support a physical SIM anywhere (Apple: iPhone Air specs). For those phones, cutting won't help. You need an eSIM.
Can you cut a SIM card to fit?
Yes, a SIM card can be cut to a smaller size, as long as you don't touch the gold contacts. It only works in one direction: standard to micro, standard to nano, or micro to nano. You can't make a nano SIM bigger by cutting.
Before you start, know the risks:
- You can destroy the SIM. If you cut into the gold chip, the card is dead and you'll need a replacement from your carrier anyway.
- You can damage your phone. Rough edges or a card that's too thick can get stuck or bend the contacts in the SIM slot. Sony, for example, tells Xperia owners: "Do not cut your SIM card, as this may damage your device" (Sony Xperia Help Guide).
- The chip has to fit inside the new outline. If the nano outline crosses the gold area on your card, stop: you can't cut that card to nano.
If you can wait a day or two, the safer options below are usually better. If you still want to cut, here's how.
How to cut a SIM card to nano or micro size
What you need
- sharp scissors, or a SIM cutter (a small punch tool with micro and nano holes),
- a fine pen and a ruler with millimetres, or a printed SIM cutting template at 100% scale,
- a nail file or fine sandpaper,
- your phone's SIM tray, to test the fit.
1. Turn off your phone and take out the SIM
Write down anything you need from the SIM first. If the cut goes wrong, you'll still have your number on your account, but you'll need a new card from your carrier.
2. Mark the new outline around the chip
Draw the new size centred on the gold contacts: 12.3 × 8.8 mm for nano, or 15 × 12 mm for micro. Copy the cut corner (the notch) on the same corner as the original card, because the tray only fits the card one way (Apple).
3. Cut slowly along the line
Cut just outside your line, a little at a time. Never cut into the gold area. With a SIM cutter, line the chip up carefully in the nano or micro hole and press once. Keep the leftover plastic frame if you might need the old size again.
4. Smooth the edges
File off any sharp corners or burrs and wipe off the dust. Rough edges are what get stuck in a tray. If you're cutting a micro SIM to nano, don't try to sand the card thinner: you could damage the chip.
5. Check the fit and test the SIM
Put the SIM in the tray the same way the old one sat, with the notch in the matching corner. It should lie flat without pushing. Never force the tray back in. Turn on your phone and check you have signal. If the SIM isn't detected or the tray feels tight, stop and ask your carrier for a new SIM. If the SIM acts up afterwards, you can clean the SIM card and the slot safely.
Safer options: get a new SIM or switch to eSIM
Ask your carrier for a replacement SIM
Your phone number belongs to your account, not to the piece of plastic, so a replacement SIM keeps your number. Many carriers now send multi-size SIMs (sometimes called triple SIM or 3-in-1 SIM), where you simply pop out the size you need (T-Mobile: Triple SIM). Fees and steps vary by carrier, so ask in a store, in the carrier's app or on their help pages.
Switch to eSIM
If your new phone supports eSIM, you can often skip the SIM card completely. Your carrier installs your plan on your phone as a digital SIM, with the same number. Check first if your phone is eSIM compatible, then see how to convert your physical SIM to an eSIM. New to it? Here's what an eSIM is. Also make sure your phone isn't locked to another carrier: a carrier-locked phone won't take a SIM or eSIM from a different carrier.
Only moving your SIM to a new phone, without changing the size? Read how to put a SIM card in a different phone.
Travelling? Keep your SIM and add a travel eSIM
Many people cut a SIM because they're about to travel with a new phone. Many eSIM phones can use your home SIM and an eSIM at the same time (dual SIM). So you can leave your home SIM in the tray for calls and texts, and use a data eSIM for the internet abroad. No cutting, no new card in the post.
These travel eSIMs are data-only, install from a QR code in your email, and work on unlocked, eSIM-compatible phones.
Europe, USA and Asia plans shown · data-only eSIMs, no phone number · Find the eSIM for your destination
FAQs
Can you cut a SIM card to fit a new phone?
Yes, if you're going smaller (standard to micro or nano, or micro to nano) and you don't cut into the gold contacts. It's risky, so a replacement SIM from your carrier or an eSIM is the safer choice.
Can I cut a micro SIM to nano?
Often yes. Mark 12.3 × 8.8 mm centred on the chip, copy the notch, and cut just outside the line. If the outline crosses the gold area, don't cut. A cut micro SIM is also slightly thicker than a real nano SIM, so check it slides into the tray without force.
How do I convert a micro SIM to a nano SIM without cutting?
Ask your carrier for a replacement SIM. Many send a multi-size card where you pop out the nano SIM, and you keep your number. If your phone supports eSIM, you can also switch your line to an eSIM.
What is a SIM cutter, and which one is best?
A SIM cutter is a small punch tool with micro and nano shaped holes. It gives a cleaner cut than scissors, but the risks are the same: the chip has to sit exactly in the hole. We don't test or sell SIM cutters, so we don't recommend a brand. If you only need one nano SIM, ask your carrier for a replacement first.
Can you cut the gold part of a SIM card?
No. The gold contacts are the chip. If you cut into them, the SIM stops working.
Will I lose my number if I cut my SIM card?
No, your number is linked to your account. If the cut SIM still works, nothing changes. If it doesn't, your carrier can give you a new SIM or eSIM with the same number.
Can I make a nano SIM fit a micro or standard slot?
You can't add plastic back by cutting. Use the frame left over from your multi-size SIM, or ask your carrier for a SIM in the right size.
How many SIM card sizes are there?
Four physical sizes: full-size (credit card), mini or "standard" (25 × 15 mm), micro (15 × 12 mm) and nano (12.3 × 8.8 mm). There's also the eSIM, which is built into the phone. Learn more in our SIM card guide.
