# SIM form factors

https://www.datasim.com/technical/sim-form-factors/

Quick answer. A SIM's form factor is its physical package. Removable cards come in four ETSI sizes, from full credit-card size down to the 12.3 × 8.8 mm nano SIM. MFF2 is a 6 × 5 mm chip soldered to the board, and iSIM runs inside the module's own chip. Form factor is separate from eUICC capability and from environmental ratings.

## Simple

A SIM's form factor is its physical shape and size. The SIM's job is the same in every shape. It holds the identity and keys a device uses to join a mobile network. What changes is how it fits into the device.

### The removable cards

Removable SIMs come in four standard sizes, set by ETSI.

- **1FF** is the full credit-card size. It is rarely used in devices now.
- **2FF**, the mini SIM, is 25 × 15 mm.
- **3FF**, the micro SIM, is 15 × 12 mm.
- **4FF**, the nano SIM, is 12.3 × 8.8 mm and a little thinner than the others.

Many SIMs are supplied as a "triple cut" card. The 2FF, 3FF and 4FF outlines are pre-cut into one carrier, so you press out the size your device takes.

### Soldered and built-in SIMs

A device does not have to take a card at all.

- **MFF2** is a small chip package, about 6 × 5 mm, soldered onto the device's circuit board like any other component. It has no tray or holder.
- **iSIM**, or integrated SIM, goes further. The SIM runs in a secure area inside the cellular module's own chip, so there is no separate SIM part.

### Choosing one

A removable card is easy to swap. You can change supplier by sending a new card, and a device can be fitted with whichever SIM suits the country it ships to. The holder takes space, though, and its contacts can be affected by vibration, damp and tampering.

A soldered SIM is smaller, cannot work loose and cannot be removed and misused. It is fitted when the device is made. To change supplier later without opening the device, the SIM needs to be an eUICC that can take new profiles over the air.

That choice is separate from the shape. An eUICC can come as a removable card, and a soldered MFF2 can be an ordinary single-operator SIM. Our page on [eSIM, eUICC and MFF2](/technical/esim-euicc-mff2/) explains the difference.

### Harsh conditions

Words like "industrial grade" are not a form factor. Ask which temperature, humidity, vibration and data-retention ratings the SIM actually meets. ETSI defines classes for these, and a SIM in any shape may or may not meet them.

## Advanced

### Removable form factors in ETSI TS 102 221

ETSI TS 102 221 clause 4.0 says a UICC is either a removable module or a non-removable module embedded in the terminal, for example soldered. A removable UICC must be one of four form factors. The specification calls them ID-1 UICC, plug-in UICC, mini-UICC and 4FF. The trade names 1FF to 4FF, mini, micro and nano map onto them as follows.

| Form factor | ETSI name | Common name | Size | Thickness | Standard |
|---|---|---|---|---|---|
| 1FF | ID-1 UICC | Full size | 85.60 × 53.98 mm | 0.76 mm | ETSI TS 102 221, ISO/IEC 7810 and 7816-1 |
| 2FF | Plug-in UICC | Mini SIM | 25 × 15 mm | As ID-1 | ETSI TS 102 221 clause 4.0.2 |
| 3FF | Mini-UICC | Micro SIM | 15 × 12 mm | As ID-1 | ETSI TS 102 221 clause 4.0.3 |
| 4FF | 4FF | Nano SIM | 12.3 ± 0.1 × 8.8 ± 0.1 mm | 0.67 mm (+0.03 / −0.07) | ETSI TS 102 221 clause 4.0.4 |
| MFF2 | MFF2 | Soldered SIM | 6.00 ± 0.15 × 5.00 ± 0.15 mm | Set by the package, not fixed in the standard | ETSI TS 102 671 clause 6.2.2 |
| iSIM | Integrated SSP | Integrated SIM | Part of the module's chip | None | ETSI TS 103 666-1 and 103 666-2 |

All the removable sizes use the same contacts and electrical interface, so a SIM behaves the same whichever size it is cut to. Only the outline and, for 4FF, the thickness differ.

### Triple-cut and multi-cut carriers

Removable SIMs are often supplied in a full-size carrier with the smaller outlines pre-punched, 2FF, 3FF and 4FF nested inside one another. The chip and contacts sit in the 4FF area, and the user presses out the size the device needs. TS 102 221 also allows a 4FF to be supplied in a carrier of ID-1 width and length but 4FF thickness, positioned 18.22 mm from the top edge and 9.25 mm from the left edge.

### MFF2 and other soldered packages

ETSI TS 102 671 defines form factors for UICCs that are soldered or not intended to be easily removed. MFF2 is an 8-contact package with a 6.00 by 5.00 mm body, contacts at 1.27 mm pitch and an exposed heat pad in the middle. Each package pin maps to one of the card contacts C1 to C8, and contacts that are not used must be left unbonded. The specification also defines MFF1 and two smaller packages, MFF3 and MFF4.

From Release 18 the specification no longer ties the MFF form factors to machine-to-machine use with extended environmental conditions. An MFF2 is simply a non-removable package. Its environmental ratings are a separate matter.

### iSIM

An integrated SIM runs on what ETSI calls an integrated Smart Secure Platform (iSSP), defined in TS 103 666-2 on top of the general characteristics in TS 103 666-1. The iSSP is a secure subsystem inside a system on chip, such as a cellular module's baseband chip. Since the chip is usually soldered into the device, the SIM becomes an integral part of the device. There is no separate SIM component or socket, which saves board area and parts.

### Environmental classes

TS 102 221 clause 4.4 sets a standard operating and storage range of −25 °C to +85 °C. TS 102 671 clause 5 then defines optional classes a UICC can declare. Most apply to any form factor, but the vibration and shock classes apply only to cavity packages, and corrosion only to removable SIMs.

- **Temperature** TA −40 °C to +85 °C, TB −40 °C to +105 °C, TC −40 °C to +125 °C, each tested over 500 temperature cycles.
- **Humidity** HA, the high-humidity test from TS 102 221.
- **Vibration** VA and **shock** SA, automotive levels tested to JEDEC methods.
- **Data retention** RA 10 years, RB 12 years, RC 15 years from manufacture.
- **Minimum file updates** UA 100,000, UB 500,000, UC 1,000,000 updates of high-activity files.
- **Moisture and reflow** MA, for soldering during module manufacture (J-STD-020D, moisture sensitivity level 3, 260 °C peak), and **corrosion** CA to CD.

A UICC states its classes as a string such as TB-HA-RA, and may store it in the file EF ENV-CLASSES ('2F07'). Terms such as "industrial grade" or "automotive grade" are vendor labels with no single definition. Ask the supplier which of these classes a part meets, and check the datasheet for the rest.

### Form factor and eUICC are independent

Form factor describes the package. Whether the SIM can hold several operator profiles and load new ones remotely is a property of the chip and its software. GSMA SGP.22 defines the eUICC as a removable or non-removable UICC, and requires a removable eUICC to use a TS 102 221 form factor. So a 4FF card can be an eUICC, and an MFF2 can carry one fixed profile. See [eSIM, eUICC and MFF2](/technical/esim-euicc-mff2/) and [eSIM standards](/technical/esim-standards/).

### Choosing removable or soldered

- **Removable** suits products where the SIM may be replaced in the field, where different SIMs are fitted per market at the end of the line, or where volumes are small. The cost is a socket, board area and contacts that are open to vibration and moisture.
- **Soldered MFF2** suits sealed, mobile or high-vibration devices and products where the SIM should not be removed and used elsewhere. The SIM goes on at board assembly, so plan how a profile is loaded and changed. In practice that means an eUICC with remote provisioning, or a supplier commitment for the life of the product.
- **iSIM** needs a module that supports it, and the SIM is chosen with the module.

Whichever you choose, record the SIM's identifiers at manufacture. The [SIM identifiers](/technical/sim-identifiers/) page explains which belong to the card and which to the profile.

## Myths

- **Myth.** MFF2 means eSIM.
  **Fact.** MFF2 is a soldered package defined in ETSI TS 102 671. It can hold an ordinary single-profile SIM or an eUICC. GSMA SGP.22 allows an eUICC to be removable or non-removable, so a nano SIM card can be an eUICC too.
- **Myth.** Industrial-grade SIMs meet a standard industrial grade.
  **Fact.** "Industrial grade" has no single definition. ETSI TS 102 671 defines optional classes for temperature (up to −40 °C to +125 °C), humidity, vibration, shock, data retention and update endurance. Ask which classes a SIM meets.
- **Myth.** A soldered SIM is automatically rated for harsh environments.
  **Fact.** Package and ratings are separate. Since Release 18, ETSI TS 102 671 treats the MFF packages simply as non-removable form factors. A soldered SIM may support only the standard −25 °C to +85 °C range unless it declares an extended class.
- **Myth.** Smaller SIM cards do less than larger ones.
  **Fact.** The removable sizes share the same contacts and electrical interface. Only the outline differs, and the 4FF is slightly thinner at 0.67 mm against 0.76 mm. What a SIM can do depends on its chip and software.

## Sources

1. [Smart Cards; UICC-Terminal interface; Physical and logical characteristics (form factors, environmental conditions, EF ICCID)](https://www.etsi.org/deliver/etsi_ts/102200_102299/102221/18.04.00_60/ts_102221v180400p.pdf), ETSI, TS 102 221 V18.4.0
2. [Secure Elements; Additional UICC form factors and environmental conditions (MFF2, environmental classes)](https://www.etsi.org/deliver/etsi_ts/102600_102699/102671/19.00.00_60/ts_102671v190000p.pdf), ETSI, TS 102 671 V19.0.0
3. [Smart Secure Platform (SSP); Part 1 General characteristics](https://www.etsi.org/deliver/etsi_ts/103600_103699/10366601/17.03.00_60/ts_10366601v170300p.pdf), ETSI, TS 103 666-1 V17.3.0
4. [Smart Secure Platform (SSP); Part 2 Integrated SSP (iSSP) characteristics](https://www.etsi.org/deliver/etsi_ts/103600_103699/10366602/17.01.00_60/ts_10366602v170100p.pdf), ETSI, TS 103 666-2 V17.1.0
5. [RSP Technical Specification (eUICC definition, removable and non-removable eUICCs)](https://www.gsma.com/esim/wp-content/uploads/2023/12/SGP.22-v3.1.pdf), GSMA, SGP.22 v3.1

Checked 30 October 2026.