There are three main types in the SD memory card family. SD, SD High Capacity (SDHC™), and SD Extended Capacity (SDXC™). This article details the different specifications of all three types of SD memory cards and the speed class ratings and compatibilities that are different with each type.
Click here to jump straight to Speed Class & UHS Speed Class Ratings
Click here to jump straight to the Compatibility Summary
Aug 27, 2017 Hi! I am not sure if you got help or not, but I found that formatting my sd card on my laptop worked with no problem. I too had issues with transferring to my sd card even though it was a 32 g. I backed up my days just in case. I took the sd and plugged it. If you are not using a SD card, please skip to the next step. Most, but not all SD (Secure Digital) cards have a lock lever that write-protects the data on the card. Find the small notch on the left or right edge of the SD card. Pull the switch up OR in the direction the label states to unlock the SD card. There is a knowledge point that write protected SD card will not be displayed on other devices, except the original one. So if you did lock your SD card before, the first thing is to remove write protection from SD card. Check the lock switch beside the card or use disk utility. It can also fix SD card not showing up on Windows 10.
Additional Reference: SD Assocation Consumer Information
SD capacities range from 128MB to 2GB
Default Format: FAT16
SD cards will work in all host devices that support SD, SDHC, or SDXC
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.)
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
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-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.
Ultra High Speed Phase II (UHS-II) bus design for SDHC and SDXC was added in SD spec 4.0. This is an additional design enhacement with connector interface modifications to increase performance.
UHS-II specification defines bus architecture for options of 156MB/s and 312MB/s. Manufacturers implemented the 312MB/s option in memory cards. These are theoretical maximum limits and actual maximum performance for a specific card is defined on the label or in advertising.
Host devices will obtain the maximum UHS-II speed when both the card and the host device support UHS-II. Otherwise, the host device and card will use the highest compatible UHS-I or SD bus speed.
There is no compatibility problem using a USH-II card in a UHS-I or non-UHS device.
Speed Class & UHS Speed Class Rating
Speed class ratings define a minimum guaranteed speed of SDHC/SDXC cards. Speed class rating is important for HD video mode or camcorders, where the device is actually saving a steady stream of data. The resolution and format of the video determines the amount of steady stream data. You should consult your camera user manual for minimum speed class requirements for HD video modes.
Speed Class (SD Bus)
Class | Minimum Speed |
2 | 2MB/s |
4 | 4MB/s |
6 | 6MB/s |
8 | 8MB/s |
10 | 10MB/s |
UHS Speed Class (UHS Bus)
UHS Class | Minimum Speed |
1 | 10MB/s |
3 | 30MB/s |
For a more detailed explanation of speed class see: Difference between Speed Class, UHS Speed Class, and Speed Ratings...
SD Association: Speed Choices
Compatibility Summary
The chart below shows the host device and the memory cards supported.
| Host device (ex. cameras, video recorders, phones, readers, etc.) | Memory cards supported |
SDXC cards and host devices
- SDXC memory cards can ONLY be used with SDXC host devices.
- SDXC memory cards will NOT work with SD / SDHC host devices.
Additional info on SDXC cards and host devices
- SDXC host devices can use and support SD, SDHC and SDXC memory cards.
- SDHC host devices can use and support both SD and SDHC memory cards.
- SDHC memory cards can be used with SDHC and SDXC host devices.
A common problem: computer / laptop doesn't read a flash memory and its content is unavailable. In this guide you will find the problem types and some suggested variants of how to fix it.
The contents:
Wrong sd card formatting (the file system is incompatible with Windows)
You have formatted the sd card on Linux or Mac OS X and then connected it to PC. Windows cannot read sd card files if the file system format of the sd card is not supported.
How to fix it
We suggest formatting the sd card in a universal FAT32 format. It can be easily done with the help of a standard Windows utility and also with the help of special programs: Such as SDFormatter, JetFlash Recovery Tool, USB Disk Storage Format Tool, etc.
Please read the step-by-step guide to avoid making mistakes:
The damage of the file structure of the flash memory with a virus
Some viruses hide the data and replace it with the exe-files having the same name without actually deleting the data. One of the relatively harmless viruses of such type is Trojan-Downloader.Win32.VB.hkq. As a result of its actions, the Windows operating system hides files of the sd card. You will not be able to see the files without removing the protection and deleting the virus from it.
What to do. Any antivirus program will help you to resolve the problem and correct the errors. One of them is Dr. CureIt. Besides deleting Worms, Spyware, Hacktools from the PC, the utility will help to heal usb drives and sd cards.
1. Download and install Dr Web Cureit on your computer.
2. Click 'Select objects for scanning' and select the desired media drives and folders.
3. Run a search scanner by pressing 'Start Scanning'.
Bad sectors and other read / copy errors
The computer won t recognize sd card with read errors and bad sectors. Characteristics:
- the sd card has stopped working
- the device is recognized by the system incorrectly
- not all the files can be opened / copied correctly.
What to do
Install Flash Memory Toolkit on your computer. The program will perform a series of quick tests and check the sd card for errors. The report will point out the errors while reading / writing information. Possibly, it won't solve the problem, but you will see a true picture of the sd card state.
The sd card is broken
Never eliminate the risk of a sd card mechanical failure: as a result of an improper operation of the device, by accident or simple inadvertence. The main causes of failure:
- the physical damage of internal components,
- the damage of a memory chip,
- the closure of an electronic circuit card,
- the deformation as the result of temperature rise.
A sd card damage can be detected by sight:
- the casing is deformed,
- there are signs of melting or other damage of a mechanical nature,
- the breakage of the plug connecting the electronic circuit board and the card-reader connector.
What to do
Most likely, it's impossible to repair the sd card or it will cost a lot of money. Not every expert in your city will dare to resolder the chip: donor components have to be ordered from suppliers. Therefore, if the sd card didn't have extremely important information, it is advisable to replace it with a new one.
The usb port is incorrect or damaged (not attached to the PC motherboard)
If an external card-reader is used to connect a sd card to PC, the connection is established via usb cable. Hence, the problem may be related to a non-working usb port of the computer or the cable.
How to fix it.
Sd Sdhc Sdxc
1) Remove the sd card from the usb socket and try to read it via another ports. If everything goes well, you will hear a distinctive “winning” Windows sound and / or an icon in the system tray: which means that the sd card has been connected to the PC.
2) A card reader may be broken. If possible, use another card-reader, for example, the one embedded in the laptop.
3) It makes sense to replace the usb cable connecting the cardreader to the PC.
The sd card drivers are missing or outdated
In most cases modern operating systems сan easily identify the sd card model and spot the connected card reader. But in rare situations, Windows can cause a conflict, due to which the sd card will not be recognized as a storage device.
What to do. Make sure that the sd card is compatible with the current operating system. The information on the supported OS can be found in the documentation on the device manufacturer website. If the manufacturer recommends to install the driver, do it.
USB connector is clogged
Sometimes the conditions the sd card is under aren't the most favorable. Problems may arise also due to proper maintenance. Because of the careless storage and constant use, the sd card contacts accumulate dust interfering with the connection of the sd card to the computer.
What to do.
1) Carefully clean the sd card contacts, making sure there are no husk, dust or any other foreign objects which got into the sd card slot from your pocket.
2) the PC usb port also can be clogged with dirt and dust. Take a stick or a match and clean the slot.
SD card not showing up: answers to the questions
I took my friend's sd card. After 'cleaning' it with an antivirus it can't be spotted by any PC or any program. When you uninstall drivers through the 'Device Manager', after reconnecting the driver, a window saying 'Drivers Download' appears but the driver is not installed because of the failure. After it in the 'Device Manager' the sd card appears with the problem 'Code 10', or 'The device cannot be started'. Why wont my computer recognize my memory card?
P. S: During the connection the sound indicating that the USB is connected can be heard and the signaling led on the card reader also works.
The answer. The file table may be damaged thus Windows can't see the sd card. Try to format it with the signature software (if it's available on the manufacturer website). Or use HDD Low Level Format Tool which is a low-level formatting program.
If there is no physical damage of the drive then there are no other variants. Plus formatting is the only method of effecting the storage device with the help of a program.
When you connect a flash memory the software installs. Windows shows that the device is ready for access but the PC still does not recognize it. Why wont my computer read my memory card?
The answer. Open 'Disk Management' and check whether the flash memory is recognized as a file volume or an unallocated space. Then you have to:
- assign a new letter to the usb drive via 'Disk Management Windows'
- create a new file volume
- format the flash memory to FAT32 or exFat
I have a Silicon Power flash drive with 32 GB capacity but the computer does not see it. It appears in 'Disk Manager' as an unallocated space but when I try to create a simple file volume an error appears. As the result, the computer not recognizing sd card and Windows Explorer says 'Please insert the drive'. What to do?
The answer. You can create a new partition through the 'Disk Management' via Control Panel. A file space can be marked as RAW, but it is necessary to create a new partition on it. Besides there are specialized programs for working with partitions and formatting.
Also read the manual on how to format a usb flash drive.
I bought a Xiaomi redmi note with 4 64GB capacity, the sd card SanDisk 64GB I took out from my old phone and after I formated it with standard Windows tools to ExtFAT having standard cluster size.
Windows Explorer does not see the sd card after it has been formatted. When you try to enable it to the phone it says 'unable to safely remove the device sd card sandisk' and when you try to format it via the phone nothing happens at all. How to cope with it?
The answer.
1) Possibly the sd card model is not supported by your mobile device which happens quite often.
2) If Windows doesn't recognize exFAT try Fat32.
3) Test the card on any other Android device: can it be read? If Windows Explorer does not see the card you should open 'Disk Management' via Control Panel and check if there is an unpartitioned space. If there is than the sd card has to be formatted and the drive has to be assigned with a letter (see the answer above).
I'm trying to recover deleted photos via Recuva program but my laptop wont read my sd card after it has been connected to it via usb and the phone appears as a portable device. USB debugging icon is enabled but at the same time so is the connection through MTP. What is better to do in this situation?
The answer. When you restore files from the internal memory, you have to create its image (see the instructions) and then connect the copy of the internal memory to the PC as a separate drive. After these complicated manipulations Recuva will be able to detect the phone memory.
Sd Sdhc Memory Card 32gb
When trying to format the sd card the computer shows the message: “the drive is write protected”. I failed to format it and now the card can't be seen by the PC either. The cardreader led is working, but the sd card not showing up on computer. What can be done in this case? It's a Transcend flash drive with 32GB capacity.
Sdhc Memory Card Not Reading
The answer. Check the drive performance through Disk Management (Run diskmgmt.msc). When you connect the sd card to PC a new device should appear in the list. In order for the flash memory to appear in 'Explorer', a new and formatted drive should be created on it. All these actions are accessible via Disk Management.
Sd Card Slot On Computer
[SD card not being recognised]
whilst shooting on my camera, the SD card failed and said card not formatted. It is not even recognised on any computer. It does not even show up as existing.