Did you notice that size of the SIM card you inserted in your phone went down in time? The main reason is obvious, advancements of technology. But, there’s also the shiny golden thing on the SIM card, known as MOS integrated circuit chip. You see, that’s the only thing the phone actually needs. The plastic around it serves as an insulator, preventing the chip from touching other electronics and causing a short circuit. As such, it can be safely cut down, as long as it’s present. That explains why the SIM card sizes got smaller, but the functionality pretty much remained the same.
This is the oldest and the biggest form factor of SIM cards. For that reason, it is known as 1FF or 1st Form Factor. The card became widespread around 1991. These cards are obsolete nowadays and only serve as a relic of the past. It’s not hard to guess why. It measures 85.6 mm × 53.98 mm × 0.76 mm or 3.37 in x 2.125 in x 0.030 in, about the size of a credit card. It was able to store around 5 to 10 messages and about 20 contacts at the time, which is too little.
Only about 5 years after full-size SIM cards, mini-SIM cards, also known as 2FF or “standard SIM cards”, were introduced. They measure 25 mm x 15 mm x 0.76 mm or 0.98 in x 0.59 in x 0.030 in. As you can see, the thickness remained the same, as well as the size of the chip. It was only the plastic trim that was reduced in height and width. They were small enough to fit into the earliest mobile phones, such as Apple iPhone 1 to 3. The cards could also save about 500 contacts, and some phones had slots for two of them.
Micro-SIM cards or 3FF (3rd Form Factor) are what resembles the shape of the cards we use nowadays the most. Obviously, they’re a little bigger, measuring 15 mm x 12 mm x 0.76 mm or 0.59 in x 0.47 in x 0.030 in in size. They were introduced in 2003 but became popular with the release of the Apple iPhone 4 in June 2010. Soon after, other phone manufacturers started using them, which also the time that smartphones started becoming globally widespread.
Nano-SIM cards or 4FF are the smallest we got in terms of SIM card sizes without removing the plastic rim around the chip. They measure 0.484 in × 0.346 in × 0.026 in or 12.3 mm × 8.8 mm × 0.67 mm. If you compare it to the micro-SIM card, you will notice that the thickness was slightly reduced for the first time. They’re the most used SIM cards in 2020 and will possibly remain that way in 2021. This is due to the hybrid SIM slot, we’re pretty sure. Hybrid SIM allows you to put 2 nano-SIM cards or 1 nano-SIM and one SD card by default. You can also purchase a hybrid SIM adapter that allows you to put 2 nano-SIM cards and 1 SD card.
If you read our answer to what is a SIM card used for, and this article, you know that the plastic around is only an insulator. An embedded SIM card or e-SIM is the bare MOS chip soldered directly to the phone’s motherboard. Since the card cannot be inserted, there’s no risk of a short circuit. It measures 6 mm x 5 mm x <1 mm or 0.24 in x 0.20 in x <0.039 in. In addition to being small, it can be mass-produced, allows for an easier device waterproofing, adds security and convenience, and will make future devices slimmer. The chip can be reprogrammed to use multiple profiles and thus multiple phone numbers.