Speed Ratings of Classes of Flash Cards for Digital Cameras

12/27/2016 - Optimized for Firefox 50.1.0

COPYRIGHT 2010 thru 2017 - David R. Woodsmall

Use this information at your own risk - it may be outdated or wrong


INDEX to Flash Card Information - CLICK HERE


There are three main types in the SD memory card family - SD, SD High Capacity (SDHC), and SD Extended Capacity (SDXC). CHECK YOUR OWNER'S MANUAL TO SEE WHAT FLASH CARDS ARE SUPPORTED. As for myself, I am using mostly SanDisk Flash cards. You MUST use a flash card rated at least as fast as your camera specification calls for, or else you may experience dropouts when recording video, and longer pauses between single picture shots (non-video). Note that Manufacturers rate their own cards - not one checks the actual rate of the flash card. Secure Digital - Wikipedia: " SD Class 2 = 16 Mbit/s (2 MB/s) SD Class 3 SD Class 4 32 Mbit/s (4 MB/s) SD Class 5 SD Class 6 48 Mbit/s (6 MB/s) SD Class 7 SD Class 8 64 Mbit/s (8 MB/s) SD Class 9 SD Class 10 80 Mbit/s (10 MB/s)" - Wikipedia NOTE - I now have Class 10 cards rated at 20 MBs/second (2010) WARNING the Canon T2i will NOT shoot VIDEO on a higher than CLASS 6 card. I do not know about the T5i, T4i nor the T3i - Firmware bug? HOWEVER, You CAN use Class 10 in the T2i for pictures (not video) Here is what Rob had to say about CLASS 10 SDHC Flash Cards (scroll down) - IN 2010 - Amazon.com: "This review is from: SanDisk 16GB Extreme - SDHC Class 10 High Performance memory card (SDSDX3-016G-P31, Retail Packaging) - NEW 30MB/s version Regarding complaints about performance with HD camcorders: SDHC cards are rated in MegaBytes per second (MB/sec). HD camcorders are rated in Megabits per second (Mb/sec). There are 8 bits per Byte. Therefore, an HD camcorder with 24Mb/sec video capture requires (24Mb/sec) / (8Mb/MB) = 3MB/sec SDHC card. A Class 4 SDHC card with at least 4MB/sec data transfer is more than enough to capture full HD. Those camcorders are not designed to work with Class 6 and Class 10 cards. Remember that Full HD, 1920 x 1080 pixels = 2,073,600 pixels, or 2 Megapixels. Digital SLRs shoot at 12 Megapixels with minimal lag time between shots requiring much higher data transfer rates than HD camcorders. Consequently, people who use Extreme Class 10 SDHC cards with high speed digital SLRs seem happy, but people using them with HD camcorders are not. It can be confusing, but you must use the appropriate card for your application. Faster is not always better."

SD Flash Cards

SD capacities range from 128MB to 2GB Default Format: FAT16 SD cards will work in all host devices that support SD, SDHC, or SDXC. - SandDisk

SDHC Flash Cards

SD High Capacity (SDHC) card is an SD memory card based on the SDA 2.0 specification. SDHC capacities range from 4GB to 32GB Default Format: FAT32 Because SDHC works differently than standard SD cards, this new format is NOT backwards compatible with host devices that only take SD (128MB - 2GB) cards. Most readers and host devices built after 2008 should be SDHC compatible. To ensure compatibility, look for the SDHC logo on cards and host devices (cameras, camcorders, etc.) - SandDisk

SDXC Flash Cards

SD Extended Capacity (SDXC) card is an SD memory card based on the SDA 3.0 specification. SDXC capacities range from 64GB to 2TB Default Format: exFAT Because SDXC uses a different file system called exFAT and it works differently than standard SD cards, this new format is NOT backwards compatible with host devices that only take SD (128MB to 2GB) or host devices that only take SDHC (4GB to 32GB). Most host devices built after 2010 should be SDXC compatible. To ensure compatibility, look for the SDXC logo on cards and host devices (cameras, camcorders, etc.). NOTE: Internal card readers on laptops from 2008 and prior may NOT support SDXC cards. SDXC cards will work in SDHC compatible readers (not SD readers) if the computer OS supports exFAT. For more information on exFat see: Operating Systems that support the exFAT File System

UHSI-I - A New Classification for Even Faster Flash Cards

Ultra High Speed, Phase I (UHS-I) bus design for SDHC and SDXC cards was added in SD spec 3.0. This is a design enhancement to increase the performance of SDHC/SDXC cards. UHS Class 1 = 80 Mbit/s (10 MB/s) - SanDisk UHS Class 3 = 80 Mbit/s (30 MB/s) - for 4K video files (UHS bus) "UHS-I and UHS-II cards can use UHS Speed Class rating with two possible grades: class 1 for minimum read/write performance of at least 10 MB/s ('U1' symbol featuring number 1 inside 'U') and class 3 for minimum write performance of 30 MB/s ('U3' symbol featuring 3 inside 'U'), targeted at recording 4K video. Before November 2013, the rating was branded UHS Speed Grade and contained grades 0 (no symbol) and 1 ('U1' symbol). Manufacturers can also display standard speed class symbol (a digit encircled with 'C') alongside UHS speed class." - Secure Digital - Wikipedia UHS-I specification defines two bus architecture options for up to 50MB/s (UHS-50) and 104MB/s (UHS-104) data transfer rates. These are theoretical maximum limits and actual maximum performance for a specific card is defined on it label or in advertising. UHS is an enhancement to the original SD interface specifications. Host devices will obtain the UHS maximum speed when both the card and host device support UHS. Otherwise, the host device and card will use the slower SD maximum speed obtainable. There is no compatibility problem using a UHS card with a non-UHS device. GATHERED IN 2010: I have a UHSI-I card rated READ: 90MB/S WRITE: 45MB/S. "UHS-I cards, specified in SD Version 3.01,[40] support a clock frequency of 100 MHz (a quadrupling of the original "Default Speed"), which in four-bit transfer mode could transfer 50 MB/s. UHS-I cards declared as UHS104 also support a clock frequency of 208 MHz, which could transfer 104 MB/s. UHS-I is the only class for which products are currently available." - Wikipedia Secure Digital - Wikipedia SD/SDHC/SDXC Specifications and Compatibility SD, SDHC and SDXC Memory Cards Explained - fStopLounge SDHC vs SDXC the best memory card - 2008 - OLD article - sdhcvssdxc.org Micro SDHC vs Micro SDXC GSIII Compatability - Android Forums

INDEX - Flash Card SPEED Jump Table

BACKGROUND - of Flash cards | SD | SD Classs 2 | SD Classs 4 | SD Classs 6 | SD Classs 8 | SD Classs 10 | SDHC | SDXC | UHS | UHS Classs 1 | UHS Classs 3 |
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