Smart Card Form Factors Explained
From full-size cards to SIMs, key fobs, and wearables.
Smart Card Form Factors
The term smart card covers a wider range of physical shapes than most practitioners expect. The choice of form factor is determined by the target device slot, the deployment environment, the acceptable cost, and whether the card needs to be user-removable.
Use the Smart Card Cost Estimator to model how form factor and interface choices affect unit cost and personalisation overhead.
ID-1 Full-Size Cards
The ID-1 format (85.60 × 53.98 × 0.76 mm) defined in ISO/IEC 7810 is the most recognisable form factor: standard credit-card size. The vast majority of banking, identity, transit, and access-control cards ship in ID-1.
| Attribute | ID-1 Spec |
|---|---|
| Width × Height | 85.60 × 53.98 mm |
| Thickness | 0.76 mm (± 0.08 mm) |
| Material | PVC, PET, PC, or composite |
| Module cavity | ISO 7816 position C1–C8 (contact) |
| Antenna space | Full perimeter loop (contactless/dual) |
| Personalisation | Embossing, laser engraving, UV print |
The secure element chip is mounted in a module — a pre-packaged die on a lead frame — that is inserted into a routed cavity in the card body and bonded with conductive epoxy.
SIM Form Factors (2FF, 3FF, 4FF)
Subscriber Identity Modules are derived from ID-1 but progressively miniaturised as handset designs shrank. All three removable variants use the same contact pad layout and ISO 7816 electrical interface; only the surrounding plastic carrier differs.
| Name | Dimensions | Common name |
|---|---|---|
| 2FF | 25 × 15 mm | Mini-SIM |
| 3FF | 15 × 12 mm | Micro-SIM |
| 4FF | 12.3 × 8.8 mm | Nano-SIM |
| MFF2 | 5 × 6 mm (solderable) | Industrial/M2M |
The SIM card carries the IMSI, authentication keys (Ki), and network operator credentials. On a JavaCard-capable SIM, additional APDU-addressed applets can be post-loaded over the air.
eSIM — Embedded SIM (SGP.22 / iSIM)
The eSIM replaces a removable SIM with a soldered chip on the device motherboard. A remote provisioning server can load, switch, and delete operator profiles without physical card swap. Consumer eSIM follows GSMA SGP.22; M2M eSIM follows SGP.02.
| Property | Removable SIM | eSIM |
|---|---|---|
| Physical swap | Yes | No |
| Profile change | Physical swap | Remote provisioning |
| Profile count | 1 | Up to 8 (device-dependent) |
| Size | 4FF (12.3 × 8.8 mm) | MFF2 or integrated |
| Survivability | User-removable | Vibration/shock resistant |
| iSIM variant | N/A | Die embedded in SoC |
microSD Secure Elements
Some secure element deployments use the microSD slot as a secure element host. A microSD SE card exposes a standard SD card interface to the host OS while containing a hardened SE die internally. This allows NFC or cryptographic capabilities to be added to devices that lack a native SE.
Wearables and Modules
Contactless inlays — antenna plus chip, without a card body — can be laminated into wristbands, key fobs, stickers, and garments. The chip and antenna operate identically to a contactless ID-1 card at the protocol level; only the form factor differs. Power budgets and antenna efficiency are more constrained, which can reduce the reliable read range versus a full-size card.
When selecting a wearable form factor, verify that the antenna geometry is tuned for the deployment environment: metal proximity (as in a wristband near skin and watch case) detunes most standard inlays significantly.
For interface and standard selection, see Contact vs Contactless vs Dual-Interface.
자주 묻는 질문
Our guides cover a range of experience levels. Getting Started guides introduce smart card fundamentals. Security guides address Common Criteria certification and key management. Programming guides target developers working with APDU commands, JavaCard applets, and GlobalPlatform card management.