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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 ME/2000/XP/7/8.1 Windows ME/2000/XP/7/8.1 Windows XP/Vista/7/8.1
Notes Windows OS may require updates, please see Table 2 below
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

Table 2


Windows XP Windows Vista Windows 7 and Windows 8.1
Update to SP2 or later, then apply Microsoft update (KB955704). Use with SDXC/microSDXC compatible card reader. Update to SP1 or later. Use with SDXC/microSDXC compatible card reader. Supported – no update required, use with SDXC/microSDXC compatible card reader.



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 2000/XP/Vista/7/10/11 • 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

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