Understanding SD Card Ratings - Revision history

ErnieHorning: ErnieHorning moved page SD Cards to Understanding SD Card Ratings: The article isn't really about speed anymore—it's about decoding all the symbols printed on an SD card. That's what readers are actually looking for today.

2026-07-20T14:25:36Z

ErnieHorning moved page SD Cards to Understanding SD Card Ratings: The article isn't really about speed anymore—it's about decoding all the symbols printed on an SD card. That's what readers are actually looking for today.

ErnieHorning at 14:24, 20 July 2026

2026-07-20T14:24:47Z

Ronp5683: /* UHS SD Cards */

2015-05-31T21:18:58Z

UHS SD Cards

Ronp5683 at 03:58, 27 May 2015

2015-05-27T03:58:22Z

Ronp5683 at 21:38, 25 May 2015

2015-05-25T21:38:08Z

Ronp5683 at 17:18, 25 May 2015

2015-05-25T17:18:10Z

Ronp5683 at 17:17, 25 May 2015

2015-05-25T17:17:27Z

Ronp5683 at 17:16, 25 May 2015

2015-05-25T17:16:11Z

Ronp5683 at 17:15, 25 May 2015

2015-05-25T17:15:44Z

Admin: Blanked the page

2015-05-25T00:24:17Z

Blanked the page

@@ Line 7: / Line 7: @@
 SDHC (High capacity) 4G to 32G
-SDXC (Extended capacity) 64G to 2Terabytes
+SDXC (Extended Capacity) 64GB to 2TB
 == Standard SD Cards ==
@@ Line 59: / Line 61: @@
 (9) UHS312: UHS-II RCLK Frequency Range 26MHz - 52MHz, up to 1.56Gbps two lanes half duplex
-Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance PI SD Cards]
+The UHS class 3 devices are available from a few vendors for about the same price. For most DIY holiday lighting applications, Class 10 or U1 cards are sufficient. Higher-performance cards may improve loading times but generally provide little benefit unless the host hardware supports the faster interfaces.
-''Last edited 5-25-2015''
+''Last edited 7-20-2026''

@@ Line 61: / Line 61: @@
 The UHS class 3 devices are available from a few vendors for about the same price, why would you buy anything else?
-Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance]
+Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance PI SD Cards]
 ''Last edited 5-25-2015''

← Older revision		Revision as of 03:58, 27 May 2015
Line 63:		Line 63:
	Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance]		Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance]

−	Last edited 5-25-2015	+	''Last edited 5-25-2015''

@@ Line 39: / Line 39: @@
 U3 - 30 Mbytes/sec write speed
-Interface speeds supported
+'''Interface speeds supported'''
 (1) Default Speed mode: 3.3V signaling, Frequency up to 25 MHz, up to 12.5 MB/sec
@@ Line 62: / Line 62: @@
 Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance]

@@ Line 12: / Line 12: @@
 The maximum standard SD interface speed is 25 MBytes/second.
-Write speed markings
+'''Write speed markings'''
 circle 2 - 2 Mbytes/sec
@@ Line 24: / Line 24: @@
 circle 10 - 10 Mbytes/sec
-Interface speeds
+'''Interface speeds'''
 (1) Default Speed mode: 3.3V signaling, Frequency up to 25 MHz, up to 12.5 MB/sec
@@ Line 33: / Line 33: @@
 The UHS-I and UHS_II specifications adds faster interface speeds. Note that the host controller must support these interface options for the faster interfaces. These higher speed cards are backwards compatible, so you can use them with older hardware. The UHS-I interface runs at up to 104 Mbytes/sec, and the UHS-II up to 312Mbyte/sec.
-Write speed markings
+'''Write speed markings'''
 U1 - 10 Mbytes/sec write speed

← Older revision	Revision as of 14:25, 20 July 2026
(No difference)

@@ Line 31: / Line 31: @@
 == UHS SD Cards ==
-The UHS-I and UHS_II specifications adds faster interface speeds. Note that the host controller must support these interface options. The UHS-I interface runs at up to 104 Mbytes/sec, and the UHS-II up to 312Mbyte/sec.
+The UHS-I and UHS_II specifications adds faster interface speeds. Note that the host controller must support these interface options for the faster interfaces. These higher speed cards are backwards compatible, so you can use them with older hardware. The UHS-I interface runs at up to 104 Mbytes/sec, and the UHS-II up to 312Mbyte/sec.
 Write speed markings

← Older revision	Revision as of 17:15, 25 May 2015
Line 1:	Line 1:
	+	The package for a SD card may say Ultra High Speed Pro, but the markings on the card tell the truth. These markings are defined by the SD Card association. The write speed is slower than the read speed, since the memory must be cleared before writing new data.

	+	== Capacity markings ==
	+
	+	SD up to 2 Gbytes
	+
	+	SDHC (High capacity) 4G to 32G
	+
	+	SDXC (Extended capacity) 64G to 2Terabytes
	+
	+
	+	== Standard SD Cards ==
	+	The maximum standard SD interface speed is 25 MBytes/second.
	+
	+	Write speed markings
	+
	+	circle 2 - 2 Mbytes/sec
	+
	+	circle 4 - 4 Mbytes/sec
	+
	+	circle 6 - 6 Mbytes/sec
	+
	+	circle 8 - 8 Mbytes/sec
	+
	+	circle 10 - 10 Mbytes/sec
	+
	+	Interface speeds
	+
	+	(1) Default Speed mode: 3.3V signaling, Frequency up to 25 MHz, up to 12.5 MB/sec
	+
	+	(2) High Speed mode: 3.3V signaling, Frequency up to 50 MHz, up to 25 MB/sec
	+
	+	== UHS SD Cards ==
	+	The UHS-I and UHS_II specifications adds faster interface speeds. Note that the host controller must support these interface options. The UHS-I interface runs at up to 104 Mbytes/sec, and the UHS-II up to 312Mbyte/sec.
	+
	+	Write speed markings
	+
	+	U1 - 10 Mbytes/sec write speed
	+
	+	U3 - 30 Mbytes/sec write speed
	+
	+	Interface speeds supported
	+
	+	(1) Default Speed mode: 3.3V signaling, Frequency up to 25 MHz, up to 12.5 MB/sec
	+
	+	(2) High Speed mode: 3.3V signaling, Frequency up to 50 MHz, up to 25 MB/sec
	+
	+	(3) SDR12: UHS-I 1.8V signaling, Frequency up to 25 MHz, up to 12.5MB/sec
	+
	+	(4) SDR25: UHS-I 1.8V signaling, Frequency up to 50 MHz, up to 25MB/sec
	+
	+	(5) SDR50: UHS-I 1.8V signaling, Frequency up to 100 MHz, up to 50MB/sec
	+
	+	(6) SDR104: UHS-I 1.8V signaling, Frequency up to 208 MHz, up to 104MB/sec
	+
	+	(7) DDR50: UHS-I 1.8V signaling, Frequency up to 50 MHz, sampled on both clock edges, up to 50MB/sec
	+
	+	(8) UHS156: UHS-II RCLK Frequency Range 26MHz - 52MHz, up to 1.56Gbps per lane.
	+
	+	(9) UHS312: UHS-II RCLK Frequency Range 26MHz - 52MHz, up to 1.56Gbps two lanes half duplex
	+
	+
	+	The UHS class 3 devices are available from a few vendors for about the same price, why would you buy anything else?
	+
	+	Link to the SD cards tested with a Raspberry PI. [http://elinux.org/RPi_SD_cards#SD_card_performance]

← Older revision		Revision as of 00:24, 25 May 2015
Line 1:		Line 1:

−	~~== SD Cards ==~~