Browse our FAQs about Memory Card

General Knowledge

What are the differences between FAT16, FAT32 and exFAT file systems?

The default formatting for cards up to 2GB is FAT16.

In recent years, memory cards have gained more storage capacity; 4GB and above. The file format FAT32 is now commonly used in memory cards between 4GB and 32GB.

If a digital device supports only the FAT16 file system you cannot use a memory card bigger than 2GB (i.e. SDHC/microSDHC or SDXC/microSDXC memory cards).

Integral memory cards of 4GB or more such as those in the CompactFlash i-Pro, UltimaPro and SDHC ranges are only supported by FAT32 devices and must be formatted to FAT32.

It is best practice to format the card in your device before use, CAUTION formatting a card will delete all data, please see your device manual.



FAT 16 (FAT) FAT 32 exFAT (FAT 64)
Maximum file size 2GB* 4GB 2TB (limited by card)
SD Card type SD SDHC, microSDHC SDXC, microSDXC
PC Compatible OS Windows 10/11 Windows 10/11 Windows 10/11
Notes Windows OS may require updates,
Mac Compatible OS Mac OS 8/9/X Mac OS 8/9/X Mac OS X 10.6.5 and above


*Recommended limit by Microsoft for compatibility but can be up to 4GB

What is UHS-1 ?

“UHS-1” or more accurately “UHS-I” stands for “Ultra High Speed” – 1 and is a speed class for SDHC and SXDC memory cards. UHS-I has a bus interface speed of up to 104 MB/s. An SDHC UHS-I card will work in any SDHC compatible device at lower speeds, but to take advantage of the UHS-I speed, a UHS-I compatible device is essential. An SDXC UHS-I card will work in any SDXC compatible device at lower speeds, but to take advantage of the UHS-I speed, a UHS-I compatible device is essential. UHS-I compatible cards and devices are normally marked with the symbol below ,”UHS-I” or “I” A speed class is also defined. = Class 1 .”UHS Class 1″

What is the difference between SDUC, SDXC, SDHC and SD cards?
  • SD cards are in the following capacities 4,8,16,32,64,128,256 512MB and 1GB, 2GB only.
  • SDHC cards are available in the following capacities: 4, 8, 16, 32GB
  • SDXC cards are available in the following capacities; 64, 128, 256, 512GB, 1TB, 2TB
  • SDUC cards are available in the following capacities 4, 8, 16, 32, 64, 128TB
  • SDUC memory cards must only be used with SDUC devices.
  • SDXC memory cards can be used with SDXC devices and SDUC Devices.
  • SDHC memory cards can be used with SDHC devices, SDXC devices and SDUC Devices
  • SD memory cards can be used with SD devices, SDHC devices, SDXC devices and SDUC Devices. SDUC (Secure Digital Ultra Capacity), SDXC (Secure Digital eXtended Capacity) and SDHC (Secure Digital High Capacity) were established to meet the growing demand for data heavy apps, 8K, 4K, and HD video and high-resolution image photography. SDUC / SDXC / SDHC are all the same physical size and shape as standard SD.
I need to reformat my memory card, which method should I use?

If you have a digital camera, dashcam, or a phone it is better to format your card in the camera. If you are using the card in a device other than these, we recommend the formatting of the card using a card reader, as described below: If you are using the card in two different devices with different formats (e.g. a Digital Camera and a Phone) we would advise you to use two separate cards. If formatting in the Card Reader (WARNING: FORMATTING CAN & WILL DELETE ALL DATA) please see your device or camera manual before proceeding with a format. Be aware, by default Windows will format a memory card of 2GB or higher capacity to FAT32.

Formatting in a PC:

Windows 10/11 • Open My Computer o Locate the drive letter of your memory card o Right-click on this drive o Select Format… (This will launch the Format Utility Window) o Under the option File System select FAT32 o Click on the Start button • Press Start / Run o Type ‘cmd’ press the OK button o This will launch the MS-DOS window and prompt o Type format *: /fs:FAT32 or NTFS (* represents the drive letter that windows recognises the card as) o Press return and follow the onscreen prompts o Once the routine is complete type EXIT

If memory cards are reusable, why would I ever need more than one card?

If a memory card is used properly it will give many years of service. You could just have a single card but if you invest in 2 or 3 your flexibility is increased greatly:

  • Use an extra card when it is impractical to download your pictures, e.g. on holiday, or on the move.
  • It is sensible to set your camera to at the highest resolution (and therefore highest quality) setting. However, higher resolution images require more space, so with only one memory card you risk running out of storage space quickly. With an extra memory card this problem is eliminated.
  • Many modern digital cameras also record high quality video. These video clips use produce a lot of data, so a single memory card can become full very quickly.
  • Take more shots of your subject and select the best one without having to delete unwanted images straight away.
  • What if your only memory card gets lost or damaged? Precious holiday, birthday, wedding photos could be lost forever! Spread the risk by using 2 or 3 memory cards with your camera.
How long will data stay valid for on a memory card or USB Flash Drive ?

Memory cards and USB drives are NOT designed for long term storage. You should always backup your data on to another device. The data will normally stay valid for a period of up to 10 years if stored under normal conditions. The data cells inside carry a charge which can dissipate over time. The data can be refreshed; copy all data off card and then format the card or USB drive and then restore all data to extend the data for another 10 years.

Why does my Memory Card show less capacity than stated?

There may be a few reasons why your drive’s capacity may be lower than stated.

The first is that when your operating system formats your drive, it leaves some overhead storage for the file system, boot data, wear levelling, and “shadow storage”.

Second, computers and laptops often come with several partitions, including a hidden recovery partition. There is a chance that some of the space is taken up by this recovery partition.

The third, and the main reason, is due to the difference between how memory manufacturers, PC / Laptop manufacturers, and Windows / Android systems measure storage. Memory manufacturers use a decimal system and PC / Laptop manufacturers & Windows / Android systems use a binary system.

In simple terms:

Memory manufacturers see:

  • 1KB = 1000 bytes
  • 1MB = 1,000KB (1,000,000 bytes)
  • 1GB = 1,000MB (1,000,000,000 bytes)
  • 1TB = 1,000GB (1,000,000,000,000 bytes).

PC / Laptop manufacturers and Windows / Android systems see:

  • 1KB = 1024 bytes
  • 1MB = 1024KB (1,048,576 bytes)
  • 1GB = 1024MB (1,073,741,824 bytes)
  • 1TB = 1024GB (1,099,511,627,776 bytes)

This difference in measurement leads to a difference in how much space is shown on some PCs, Laptops, and Phones. This difference increases as the capacity of the drive increases between MBs, GBs, TBs.

Stated Capacity on Drive Windows PC/Laptop/Android Capacity Shown
1GB 0.93 GB
2 GB 1.9 GB
4 GB 3.7 GB
8 GB 7.5 GB
16 GB 14.9 GB
32 GB 29.8 GB
64 GB 59.6 GB
128 GB 119.2 GB
256 GB 238.4 GB
512 GB 476.8 GB
1 TB 0.9 TB
2 TB 1.8 TB
4 TB 3.6 TB
8 TB 7.3 TB
16 TB 14.6 TB


My device does not recognise my Integral memory card. What is wrong?
  • Make sure the memory card is not inserted upside down, this is a very common issue with memory cards in mobile phone handsets.
  • Try rebooting/switching on your device with the memory card already inserted.
  • Is your device SDHC / microSDHC compatible? – many cameras, PDA’s, mobile phone handsets and built-in card readers (on a PC) produced before Summer 2007 will not work with SDHC memory cards.
  • Check the switch on the side of the memory card is not set to the “lock” position. If the memory card is locked; move the switch to the unlock position and then try again
  • If you have a SDXC card you must use a compatible SDXC device. To use on a PC you will require a compatible device and a compatible operating system. Please click here to see our guide
  • Try another memory card
I have saved my photos back to the memory card. Why can’t I view them in the camera?

Most cameras will only view images stored within a set folder structure. If you have saved the images to new folders we suggest moving the images back to within the camera’s folder structure and you should be able to view them if in the correct format, but this may not be the case always as some cameras will only display images with the correct EXIF information. (This is extra data stored with the image).

If you have modified the original image or changed the file format using Adobe Photoshop or similar the image may now not be compatible with your camera’s operating system and so will not display on the camera’s viewing screen (the images will be perfectly safe and fine to print).

To avoid problems it is best not to save changed images back to the memory card if possible.

How can I transfer the data from my memory card to my computer?

To transfer data from a memory card to a PC – The PC has to recognise the memory card as a removable drive. It is good practice to back up data kept on a card. This can be done in a number of ways including.

  • Leaving the memory card in your device and connecting your device (usually via a USB cable) to your PC. (Please see your device manual for instructions)
  • Using a suitable memory card slot on your PC if available. Insert the memory card correctly into the appropriate slot on your PC. The memory should show as a “removable drive” in your operating system. (Please note some newer cards may not work in older slots e.g. A SDHC card will not work in a SD only slot)
  • Using an external memory card reader – Connect the memory card reader to your PC and then insert the memory card. The memory should show as a “removable drive” in your operating system. (Please note some newer cards may not work in older reader e.g. A SDHC card will not work in a SD only reader)

Make sure that your internal or external card reader and operating system are compatible with your card and format eg a SDHC card will need a SDHC reader, a SDXC card will need a SDXC reader and a operating system compatible with the exFAT format.

Once the memory card is recognised your can cut-and-paste or drag-and-drop data to and from the memory can as you would with any other drive.

Caution: Do not remove the memory card or turn off the power whilst reading or writing data this could corrupt data.

Why do digital memory cards sometimes become “unreadable” ?

This problem is not related to any particular brand of memory card or device. It can occur when the device had been interrupted when accessing the memory card.

To avoid this problem:

  • DO NOT turn OFF the device or remove the memory card while the device is reading, writing, erasing or formatting.
  • DO NOT use the device while the batteries are low. This could result in corruption. In some cases power can run out as the memory card is being written to.
  • AVOID inserting and removing the memory card with the device switched ON.
  • To fix this problem you will need to reformat the memory card (this will destroy all data held on the card).
  • You may be able to recover images from a corrupted memory card before formatting (see FAQ on reformatting the memory card).
  • Some cameras will not access memory cards that have been formatted in a Card Reader, so please read your camera manual before proceeding with a format.
  • When using card readers make sure the readers light is not flashing and wait a few seconds before pulling the card out of the card reader slot.
My SD Card is write protected – how do I unprotect it?

SD cards have a write lock. This is a switch on the side of the card. The DOWN position is write protect ON and the UP position is write protect OFF.

To use the device in a camera the position of the switch must be UP. It is a good idea to write protect a card with important data.

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