The main difference between eSIM and nano-SIM lies in their form factors, with eSIM being an embedded SIM/ SIM chip (MFF2: 5mm x 6mm x 1mm) soldered into the device, while a nano-SIM is a removable SIM card (12.3mm x 8.8mm x 0.67mm) inserted into a compatible SIM card slot. However, in terms of eSIM, the meaning is a bit more complicated.

What Is a Nano SIM?

A nano SIM is one of the formats or forma factors of a SIM and IoT SIM. It’s also known as 4FF and is the fourth generation of SIM cards, being only 12.3mm x 8.8mm x 0.67mm.  It requires a smaller SIM card slot, providing greater design flexibility for modern smartphones and IoT devices. Nano SIMs are only available in commercial grade, which may not be suitable for industrial applications with extreme conditions.

eSIM and eUICC Confusion

eSIM is a broader and more confusing notion nowadays. It can be referred to as a SIM chip or MFF2 form factor, which is embedded within IoT devices by soldering it onto the circuit board. At the same time, it’s often used interchangeably with eUICC. An eUICC-enabled SIM card, regardless of its form factor, incorporates technology and software for remote provisioning of carrier profiles, eliminating the need for physical card replacement. eUICC allows for over-the-air (OTA) management, enabling, disabling, and downloading of Mobile Network Operator (MNO) profiles. In contrast, traditional SIM cards lacking this technology would require physical replacement with another operator's SIM card. If compared to Soft SIM, it’s more logical to view it as a format in this particular case.  Unlike traditional SIM cards, eSIMs (MFF2) are resilient to vibrations, movement, moisture, and corrosion. As a result, MFF2 IoT SIM chips have become an ideal solution for verticals like the utility sector and consumer electronics.

What Are the Differences between Nano SIMs and eSIMs (MFF2)?