SD and microSD Memory Cards

Card format and capacity class: what your device accepts

Start with the physical size and the capacity family. Full-size SD fits cameras, while microSD fits phones, drones, action cameras and handheld consoles, and an adapter lets a microSD card sit in a full-size slot but never the other way round. SDHC covers up to 32 GB, and SDXC covers everything larger, up to 2 TB. A device that supports only SDHC cannot read an SDXC card, because SDXC cards use the exFAT file system, so check the maximum capacity in your device manual before choosing 256 GB or 1 TB.

Speed marks for 4K video, burst shooting and apps

Read the markings, not just the biggest number on the label. Maximum read speed describes copying files to a computer, while a camera cares about the minimum sustained write speed. Class 10 and U1 both guarantee 10 MB/s, and U3 and V30 guarantee 30 MB/s, the usual floor for 4K video. A1 and A2 describe random access for running apps or games from the card, so they matter in phones, handheld consoles and single-board computers more than in cameras.

Match the card to the workload. A dash camera or security camera rewrites its card constantly, so a high-endurance card built for continuous recording lasts longer than a standard one. Burst photography and high-bitrate video benefit from the faster write figures, while a card for keeping photos or music is fine at Class 10. Cards sold as a single pack or with an adapter differ only in what is included, so check the title for the variant.

Questions about SD and microSD Memory Cards

Will an SDXC card work in an older camera?

Only if the camera supports SDXC. Older cameras and some card readers handle SD and SDHC only and cannot read exFAT. Check the manual for the maximum card capacity, and pick an SDHC card of 32 GB or less if no larger size is listed.

What do U3, V30 and A2 mean on a card?

U3 and V30 both guarantee 30 MB/s minimum sustained writing, which suits 4K video. A1 and A2 rate random read and write performance for apps and games, with A2 the faster tier. None of these marks changes how much the card can hold.

Do I need a high-endurance card for a dash cam?

A dash cam overwrites its card in a loop for hours each day, which wears ordinary cards faster. A card marketed as high endurance is built for that continuous recording, so it is the safer match for dash cams and home security cameras.