SIM Card Sizes Explained: Nano, Micro and Standard
The Three SIM Card Sizes
Since the first mobile phones, SIM cards have been getting smaller. Today there are three physical SIM card sizes in use, though only one is common in modern smartphones. Here is a breakdown of each size, its dimensions and where you will find it.
| SIM Type | Dimensions | Used In |
|---|---|---|
| Standard SIM (Mini SIM) | 25 x 15 mm | Older phones (pre-2010), some IoT devices and legacy equipment |
| Micro SIM | 15 x 12 mm | Older smartphones (2010–2014), including iPhone 4, Samsung Galaxy S3/S4 |
| Nano SIM | 12.3 x 8.8 mm | All modern smartphones since approximately 2014, including all recent iPhones, Samsung Galaxy and Google Pixel models |
Which SIM Size Does My Phone Need?
If your phone was made after 2014, it almost certainly uses a nano SIM. This includes:
- Apple — iPhone 5 and all later models
- Samsung — Galaxy S6 and all later models, Galaxy A series, Galaxy Z Flip/Fold
- Google — Pixel 1 and all later models
- OnePlus, Xiaomi, Sony, Motorola — all recent models use nano SIM
If you are unsure, check the SIM tray on your phone. Nano SIMs are the smallest size — roughly the size of a fingernail. You can also look up your phone model on the manufacturer's website for the exact specification.
What Is a Multi-SIM or Trio SIM?
Most UK networks now supply a 3-in-1 SIM card (also called a trio SIM or multi-SIM). This is a single card with pre-cut outlines for all three sizes — standard, micro and nano. You simply snap out the size you need.
This means you no longer need to specify which SIM size you want when ordering. The card adapts to any phone.
Networks That Supply 3-in-1 SIMs
- EE — yes
- Vodafone — yes
- O2 — yes
- Three — yes
- giffgaff — yes
- SMARTY — yes
What If I Have the Wrong SIM Size?
If your current SIM card does not fit your new phone, you have two options:
- Request a free SIM swap — contact your network and ask for a replacement SIM in the correct size. All major UK networks do this for free. See our SIM swap guide for step-by-step instructions.
- Use a SIM adapter — if your SIM is too small (e.g. nano SIM in a micro SIM slot), you can use a cheap plastic adapter. However, these can get stuck in the tray, so a SIM swap is the safer option.
Do not cut your SIM card. While it is technically possible to trim a larger SIM down to a smaller size, you risk damaging the chip and rendering the SIM useless. A free SIM swap is always the better choice.
The Future: eSIM
Physical SIM cards are gradually being replaced by eSIM (embedded SIM) technology. An eSIM is a digital SIM built into the phone — there is no card to insert at all. You activate it by scanning a QR code or using your carrier's app. Most flagship phones released since 2020 support eSIM alongside a nano SIM slot. To learn more, read our guide on what an eSIM is and how it works.
Managing SIM cards across a business fleet? Connection Technologies handles provisioning, eSIM setup and SIM swaps for your entire team. Get a free quote or call 0333 015 2615.
