Most U.S. prepaid kits today ship a nano-SIM — the smallest common format — often nested inside a punch-out card that also contains micro and standard outlines for older devices.
Size history in brief
Standard SIM (25 × 15 mm) dominated early smartphones. Micro-SIM (15 × 12 mm) appeared as handsets shrank. Nano-SIM (12.3 × 8.8 mm) is the default for phones sold in the U.S. since the mid-2010s.
Reading a retail SIM card
The gold contact pad carries the chip; the plastic frame is disposable. Never trim a SIM yourself unless a manufacturer documents safe sizing — improper cuts destroy the chip contacts.
- Locate your phone’s SIM tray type before opening a kit.
- Use the smallest punch-out that fits — do not leave excess plastic in the tray.
- Power off before ejecting or inserting to avoid profile corruption on some models.
Dual-SIM phones
Many modern handsets accept nano-SIM plus eSIM simultaneously. Descriptions should specify whether both slots can be active for data or if one is limited to voice/SMS.