What does 100x mean, for an SD card?

13

When I read the information about an SD card, I notice there is an information that is reported as 100x. What does that mean? To what is it referring?

kiamlaluno

Posted 2010-08-23T05:50:42.937

Reputation: 1 390

Answers

12

The x rating on an SD card is a measurement of read/write speed. 1x means a speed of 1.2 Mb/s, so 100x would mean a maximum speed of 120 Mb/s (or 15 MB/s). Whether or not this refers to maximum write speed or maximum read speed is vendor-specific.

goldPseudo

Posted 2010-08-23T05:50:42.937

Reputation: 2 100

I guess they will report the read access speed, to make think the SD card is more performant than it is. :-) Thank you for your reply. – kiamlaluno – 2010-08-23T23:52:08.190

It should also be noted that the speed is pretty much always given as a maximum (as in up to) as opposed to average speed. – Synetech – 2012-01-23T02:57:16.037

3To be precise, the convention is that the speed is given in the same format as for CD drives, so 1x is as gP says 1.2 Mb/s or the perhaps more known number 150 kB/s. – nitro2k01 – 2012-08-14T00:55:57.710