Editing SD card (section)

=== "×" rating ===
{{main|CD and DVD writing speed}}

{| class="wikitable" style="background:white; float:right; margin-left:1em;"
|-
! valign="top" | Rating
! valign="top" | Approx.<br />(MB/s)
! valign="top" | Comparable<br />speed class
|- style="text-align:center;"
| 16×
| 2.34
| [[File:SDHC Speed Class 2.svg|28px]] (13×)
|- style="text-align:center;"
| 32×
| 4.69
| [[File:SDHC Speed Class 4.svg|28px]] (27×)
|- style="text-align:center;"
| 48×
| 7.03
| [[File:SDHC Speed Class 6.svg|28px]] (40×)
|- style="text-align:center;"
| 100×
| 14.6
| [[File:SD Class 10.svg|28px]] (67×)
|}

Initially, some manufacturers used a "×" rating system based on the speed of a standard [[Optical disc drive|CD-ROM drive]] (150&nbsp;kB/s or 1.23&nbsp;[[Mbit/s]]),{{efn|reference=1 KB = 1024 B}} but this approach was inconsistent and often unclear. It was later replaced by standardized Speed Class systems that specify guaranteed minimum write speeds.<ref name="SDHCspec" /><ref name="sda_speed_class_consumer" /><ref name="sda_logos_2017">{{Cite web |title=SD Standards Brochure 2017 |url=https://www.sdcard.org/consumers/pdf/2017SDA_brochure_eng.pdf |url-status=dead |archive-url=https://web.archive.org/web/20170330174639/https://www.sdcard.org/consumers/pdf/2017SDA_brochure_eng.pdf |archive-date=2017-03-30 |access-date=2017-03-29}}</ref><ref>{{cite web |title=Flash Memory Cards and X-Speed Ratings |url=http://www.kingston.com/us/flash/x-speed |url-status=dead |archive-url=https://web.archive.org/web/20170702204220/http://www.kingston.com/us/flash/x-speed |archive-date=2017-07-02 |access-date=2017-08-05 |publisher=Kingston}}</ref>