SIM Card Sizes, from Mini to eSIM

There have been four physical SIM sizes, and the useful thing to know is that the part that does the work never changed. The gold contact area is the same on all of them. Every "new size" was the industry trimming plastic away from an identical chip.

That is why the sizes nest inside one another, and why eSIM is the logical end of the sequence rather than a fifth entry in it — the last of the plastic finally gone.

Formally these are 1FF through 4FF — form factors one to four — and the phrase really does come from a specification document: ETSI TS 102 221 defines the physical characteristics of the card for every phone that takes one, which is why a SIM from any operator fits any tray.

• Full-size (1FF), 85.6 × 53.98 mm — a credit card. Gone since the mid-1990s.
• Mini (2FF), 25 × 15 mm — the one most people still picture when they hear "SIM card".
• Micro (3FF), 15 × 12 mm — the transitional size, roughly 2010 to 2014.
• Nano (4FF), 12.3 × 8.8 mm — the current standard, and barely larger than the contacts themselves.

Nano is where the trimming stopped, because there was nothing left to trim. The next step had to remove the card rather than shrink it.

Because the sizes nest, cutting a larger card to a smaller size sometimes works, and this was common practice around 2012. It is a bad idea now, and Apple says so in as many words: cutting or modifying a SIM card may stop it connecting, and the resulting damage is not covered by the warranty.

An eSIM is the same secure chip soldered permanently to the phone’s board, with the credentials delivered over the internet instead of pre-loaded at a factory. There is no card, so there is no size — asking what size an eSIM is has no answer.

The practical difference is that one chip holds several profiles at once where a card held exactly one. How that works is the mechanism behind every travel plan on this site.

Two checks settle it, and neither needs the manual. The second is the same one that answers whether the phone supports eSIM:

1. 1Any phone sold in the last decade takes nano, if it takes a card at all.
2. 2Dial *#06#. An EID alongside the IMEI means eSIM support too — and on a growing number of models there is no tray at all.

That last group keeps widening. Apple’s list of which SIM each iPhone uses has US models from the iPhone 14 onward as eSIM-only, and the iPhone 17 line and iPhone Air as eSIM-only across a dozen countries and regions; Google’s dual-SIM guidance for Pixel says the same of US Pixel 10 models other than the Pro Fold.

Increasingly, none of it. A travel eSIM installs alongside whatever your main line already is, card or not, and leaves it untouched. Plans by destination, ranked on price per GB.