Western Digital Previews 4 TB SD Card: World’s Highest-Capacity

Western Digital this week is previewing the industry’s first 4 TB SD card. The device is being showcased at the NAB trade show for broadcasters and content creators and will be released commercially in 2025.

Western Digital’s SanDisk Extreme Pro SDUC 4 TB SD card complies with the Secure Digital Ultra Capacity standard (SDUC, which enables up to 128TB). The card uses the Ultra High Speed-I (UHS-I) interface and is rated for speed Class 10, therefore supporting a minimum speed of 10 MB/s and a maximum data transfer rate of 104 MB/s when working in UHS104 (SDR104) mode (there is a catch about performance, but more on that later). WD’s SD card is also rated to meet Video Speed Class V30, supporting a minimal sequential write speed of 30 MB/s, which is believed to be good enough for 8K video recording, above and beyond the 4K video market that Western Digital is primarily aiming the forthcoming card at.

For now, Western Digital is not disclosing what NAND is in the SanDisk Extreme Pro SDUC 4 TB SD card. Given the high capacity and relatively distant 2025 release date, WD may be targetting this as one of their first products to use their forthcoming BiCS 9 NAND.

And while not listed in WD’s official press release, we would be surprised if the forthcoming card didn’t also support the off-spec DDR200/DDR208 mode, which allows for higher transfer rates than the UHS-I standard normally allows via double data rate signaling. Western Digital’s current-generation SanDisk Extreme Pro SDXC 1 TB SD card already supports that mode, allowing it to reach read speeds as high as 170 MB/s, so it would be surprising to see the company drop it from newer products. That said, the catch with DDR208 remains the same as always: it’s a proprietary mode that requires a compatible host to make use of.

Western Digital has not disclosed how much will its SanDisk Extreme Pro SDUC 4 TB SD card cost. A 1 TB SanDisk Extreme Pro card costs $140, so one can make guesses about the price of a 4 TB SD card that uses cutting-edge NAND.

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