What are SIM form factors?

SIMs are manufactured in a range of five standardised sizes, known as form factors. Learn more about their suitability and differences between them here.

SIMs (subscriber identity modules) are manufactured in a range of standardised sizes, known as form factors. The five SIM form factors are 1FF (the largest), 2FF, 3FF, 4FF and MFF2 (the smallest).

Discover more about the differences between these form factors, and their suitability for various use cases.

In all the 1FF – 4FF formats, the SIM chip is incorporated into a dedicated card, which is inserted and removed from the device via a tray mechanism. With eSIM however, a vacuum-sealed SIM chip is soldered directly onto a board within the device. It is also much smaller than any of the removable formats.In many use cases, an eSIM incorporates a type of software standard known as eUICC (Embedded Universal Integrated Circuit Card). This allows a single chip to host multiple SIM profiles. It also makes it possible to add, remove and manage these profiles over the air via a method called remote SIM provisioning (RSP). Note: usage of eUICC is not confined to Embedded SIM. You can deploy it with other SIM form factors, too.Usage of the term eSIM can be variable in industry. Some use eSIM to simply mean Embedded SIM. Others, including Wireless Logic use eSIM to mean eUICC.

In many use cases, an eSIM incorporates a type of software standard known as eUICC (Embedded Universal Integrated Circuit Card). This allows a single chip to host multiple SIM profiles. It also makes it possible to add, remove and manage these profiles over the air via a method called remote SIM provisioning (RSP). Note: usage of eUICC is not confined to Embedded SIM. You can deploy it with other SIM form factors, too.

Usage of the term eSIM can be variable in industry. Some use eSIM to simply mean Embedded SIM. Others, including Wireless Logic use eSIM to mean eUICC.

1FF
(Full size)

Size:
85.6mm x 53.98mm x 0.76mm

With dimensions similar to a credit card, this form factor is no longer used in modern devices. You are only likely to encounter it in legacy equipment.

2FF
(Mini)

Size:
25mm x 15mm x 0.76mm

Up until the introduction of 3FF and 4FF SIMs in 2010 and 2012 respectively, the mini-SIM was the industry-standard form factor for nearly a decade. Although its usage has now declined, it is still found in various devices; particularly larger industrial and commercial equipment (e.g. vending machines), and fleet tracking devices.

3FF
(Micro)

Size:
15mm x 12mm x 0.76mm

The Micro SIM first saw widespread use when it was incorporated in the original Apple iPad. Common applications include handheld industrial equipment, tablets and health monitors.

4FF
(Nano)

Size:
12.3mm x 8.8mm x 0.67mm

The Nano SIM is not only smaller but also thinner than its predecessors. The design also incorporates a rim around the contact area to prevent short-circuiting. The compact sizing makes these SIMs a popular choice for wearables and small portable devices.

MFF2 (Machine-to-Machine Form Factor)

Size:
5mm x 6mm x 1mm

This chip form factor is also known as Embedded SIM (eSIM).

A SIM contains all the information a device needs to access a network, and for networks to authenticate users, all in one place. It means that devices can connect with each other securely and rapidly. Strong authentication prevents the cloning of devices. Thanks to the ability to embed SIM cards in the device during manufacturing, it makes it much more difficult to gain unauthorised physical access to the SIM.

If you deploy IoT devices in multiple regions, or if devices are designed to be used on the move, you have the option of utilising your network provider’s roaming agreements with other carriers. Furthermore, thanks to eUICC, there is also the option of holding multiple SIM profiles on the same device, and those devices can be configured to use profiles which best match the commercial, operational or regulatory requirements in different parts of the world. In this way, SIMs provide a wide choice of options for extending your reach, depending on your cost and coverage preferences.

Thanks to remote SIM provisioning technology, it is possible to switch networks and reconfigure your connectivity settings without the need for physically accessing your SIMs. This can significantly reduce the time and cost required for device configuration and deployment. With the right SIM provisioning and management platforms in place, it becomes possible to control your connected assets across multiple networks, all in one place.

In all sectors, connectivity cost preferences and device size are usually the main deciding factors for choice of SIM form factor. For example, consumer-focused applications, Nano SIMs are often a good choice for wearables and other very small pieces of equipment, whereas Micro SIMs can be a good fit for domestic energy meters and other ‘smart home’ applications.

If your plans involve a roll-out of IoT devices across a range or regions, an eSIM or eUICC SIM may be an attractive option. All devices can receive the same eSIM at the manufacturing stage, and devices can later be remotely provisioned with a relevant profile, depending on the market they are destined for. This approach can mean a quicker and less expensive project rollout.

For industrial applications, as well as connected component size and connectivity preferences, it’s also important to factor in environmental considerations when selecting the right SIM card.

As it’s soldered into the device, an eSIM design can help ensure the integrity of the chip. For the removable 2FF – 4FF form factors, you can also opt for industrial-grade SIMs. Typically, these can withstand temperatures of between -40C and +105C. They also have an extended lifecycle — up to 15 years in many cases.

For use cases such as engine telematics and GPS tracking, the appropriate form factor is once again determined by connectivity preferences, component size and environmental conditions. For a dashboard-based tracker, a standard Micro or Nano SIM might be a good option. However, for an engine performance sensor or refrigeration asset monitor, a specialist automotive SIM may be the best option. Like industrial variants, automotive SIMs are designed to operate effectively in harsh environments and at extreme temperatures.