A memory card looks like a simple thing, yet its packaging has a pile of markings and classes. Choose the wrong one and the camera will not record 4K or the phone stutters. Let us explain what those markings mean and which card to choose.

SD versus microSD

They differ mainly in size. microSD is tiny and goes into phones, drones, action and security cameras. SD is larger and used in cameras and laptops. A microSD can be inserted into an SD slot via the included adapter.

Capacities: SDHC, SDXC and SDUC

The marking tells you the maximum capacity:

  • SDHC up to 32 GB.
  • SDXC up to 2 TB, the most common today.
  • SDUC even more, for special use.

Older devices may not handle large cards, so check support.

Speed classes: watch out for this

This is where it is decided whether the card can handle smooth video. There are several markings at once:

  • UHS Speed Class: U1 (10 MB/s) and U3 (30 MB/s).
  • Video Speed Class: V10, V30, V60, V90 by the minimum write speed for video.
  • Application Class: A1 and A2 for fast app launching, important in phones.

Simply put: for 4K video you need at least U3 or V30, for apps in a phone A2.

Read versus write

Manufacturers like to state a high read speed, but when recording video the write speed decides, and it tends to be lower. That is exactly what the V and U classes guarantee.

What to watch out for

  • Counterfeits. Cheap cards from dubious sources lie about both capacity and speed. Buy trusted brands.
  • A card is not a backup. Memory cards wear out and can fail, so regularly back up important data from them.

Which card for what

DeviceRecommended card
PhonemicroSD U1, ideally A2
4K camera or dronemicroSD U3 or V30
Security cameramicroSD U1 to U3 (withstands constant writing)
Professional photo and videoSD V60 or V90

Not sure which card suits your device? Get in touch, we will advise and also help with transferring and backing up data.