Choosing memory cards
Cards for cameras write all day, so sustained write speed and endurance matter more than the read speed printed on the pack. Choose by capacity, speed class and the largest card the device supports.
- Maximum card size
- Check the largest microSD card the device supports. Wi-Fi cameras in this range take up to 256 GB, project cameras up to 512 GB, and dash cameras up to 512 GB or 1 TB.
- Speed class
- Continuous recording needs a guaranteed write speed. U3 and V30 marks guarantee at least 30 MB/s of sustained writing, and Class 10 guarantees 10 MB/s.
- Endurance
- Constant overwriting wears flash memory. Cards sold for continuous recording are tested for many more write cycles than standard cards, so use them in cameras that record around the clock and replace them on a schedule.
- Recording time
- A card holds about 10.8 GB per day for each 1 Mbps of video, so a 128 GB card lasts about six days at 2 Mbps and about three days at 4 Mbps. Cameras overwrite the oldest footage when the card is full.
- Genuine cards
- Counterfeit cards often report a larger capacity than they have and fail when the real capacity is used. Buy through an authorised channel, and test a new card before putting it into service.