What is Secure Digital Extended Capacity card (SDXC)?

Types of SD cards

SD cards are available in different sizes and capacities. Early cards were limited to capacities of up to 2 GB. Secure digital high capacity (SDHC) cards can store 2 GB to 32 GB of data. The SDXC standard is a step up from SDHC's capacities, with cards capable of storing between 32 GB and 2 TB of data.

Recent memory card technology has evolved even further with the development of the Secure Digital Ultra Capacity format. Introduced in 2019, the SDUC standard supports cards with capacities ranging from 2 TB to 128 TB.

In addition to capacity, SD cards also differ in terms of file system compatibility. The smallest SD cards use the FAT16 system, while SDHC cards use FAT32. In contrast, SDXC cards use Microsoft's exFAT (extensible file allocation table) storage system, which allows for greater capacity and larger file sizes compared to SD or SDHC cards. This system also improves the performance and reliability of SDXC cards.

SDXC format

For SD cards, the Extended Capacity (XC) format increases the maximum SD storage capacity more than 60-fold. A 2 TB SDXC memory card can store up to 100 full-length movies, 480 hours of music or 136,000 high-quality color photographs. (These numbers are approximations as file sizes will affect the number of items that can be stored on a card.)

The XC technology was originally conceived for the camcorder market, but it allows for greatly increased storage in other applications as well. SDXC cards are highly suitable to expand the internal storage capacity of devices like smartphones, allowing users to store more photos, videos, apps and other content on the device. SDXC cards are also an ideal storage medium for SLR cameras and action cameras, and for storing ultra-high-resolution video and other types of multimedia.

The evolution of SDXC cards

SD, SDHC and SDXC standards and protocols are all provided by the SD Association (SDA). The first ever SD cards were released by SanDisk, Toshiba and Panasonic in late 1999. These companies formed the SDA in 2000 to continue development on the SD card standard. Derived from the multimedia card format, the SD format was first available in 32 MB and 64 MB capacities. Over the years, SD cards of higher capacities (256 MB, 512 MB, etc.) also became available, along with newer iterations of the SD physical format, such as miniSD and microSD.

In January 2009 the SDA announced the SDXC format at the Consumer Electronics Show. This new format significantly increased the storage capacity of SD cards. One of the first SDXC cards was released in March 2009, with a storage capacity of 32 GB and a read/write speed of 400 MBps. Then, from 2010 onward, other companies released higher capacity SDXC cards, including Toshiba, Panasonic, SanDisk, Lexar and Samsung.

Along with new SDXC cards, many companies also released new compatible devices and card readers post-2009. Together, these developments helped to expand the range of available high-capacity consumer electronics. Additionally, by providing greater storage capacities and supporting higher data transfer rates, SDXC cards also provided users with the freedom to store more information and files on their devices.

SDXC vs. SDHC cards

Both SDHC and SDXC offer higher memory capacity than standard SD cards (4 GB to 32 GB for SDHC and 32 GB to 2 TB for SDXC), but both also offer higher read/write speeds than SD. According to the SDA, high-speed SDXC and SDHC offer bus speeds of up to 25 MBps, while SDXC and SDHC with the UHS-III bus interface offer bus speeds of up to 624 MBps full duplex.

SDXC cards are backward compatible with electronic devices that support SDHC and SD formats. Even so, with older devices, it's important to check if they support SDXC by confirming that they recognize the exFAT file system used by SDXC. Similarly, SDHC may not be compatible with older devices that support SD cards so it's important to check device specifications (including operating system version) to avoid compatibility issues.

MicroSDXC cards

The first microSDXC card, released in August 2017 by SanDisk, had a capacity of 400 GB. Over the next few years, other companies released higher capacity microSDXC cards, including Integral Memory, Kingston and PNY (512 GB), as well as Micron and SanDisk (1 TB). Today, microSDXC cards are available that are capable of holding anywhere from 32 GB to 2 TB of data.

MicroSDXC-compatible devices will also work with microSDHC and microSD cards. In general, any device that supports the microSDXC standard will be backward compatible with older standard microSD cards. However, such devices may not support the newer micro Secure Digital Ultra Capacity format that was introduced in 2019, with cards of capacities between 2 TB and 128 TB.

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