128TB SD Cards Still Not on Store Shelves for Most People

SDUC cards promise up to 128TB of storage, but finding them in stores is very hard. Even 2TB cards are rare for shoppers.
By Newsroom | Technology, Storage |

The promise of Secure Digital Ultra Capacity (SDUC) memory cards reaching up to 128 terabytes (TB) has been on the horizon for years, with the standard first outlined in 2018. While the SD Association states these multi-terabyte cards are already in use in certain sectors, consumers seeking these massive storage solutions in everyday retail channels face significant scarcity. This creates a gap between the stated capabilities of the SDUC standard and its current tangible availability for the general public.

SDUC promised 128TB memory cards: The engineering wall keeping SD cards at 2TB - 1

Timeline of SDUC Development and Announcements

The journey toward high-capacity SD cards began with the definition of the SDUC standard, which expands the maximum storage limit significantly beyond previous specifications.

SDUC promised 128TB memory cards: The engineering wall keeping SD cards at 2TB - 2

  • June 2018: The SD Association (SDA) announces the SD 7.0 specification, introducing SD Express for faster speeds and SDUC for expanded capacity up to 128TB. The theoretical maximum transfer rate for SD Express is 985 megabytes per second (MB/s).

  • April 2020: The SDA's SD Express standard, initially offered on SDUC, SDXC, and SDHC cards, is discussed as a potential way to achieve 128TB capacity and 985MB/s transfer rates.

  • October 2023: The SDA officially outlines the capacity tiers: SD up to 2GB, SDHC up to 32GB, SDXC up to 2TB, and SDUC from over 2TB up to 128TB, all using the exFAT file system for capacities over 2TB.

  • April 2024: Western Digital showcases a 4TB SDUC SD card prototype.

  • September 2025: The SDA highlights the SDUC standard and its ability to overcome the 2TB limit of SDXC.

  • November 2024: A Linux kernel update (6.11) adds support for SDUC and UHS-II SD cards, noting that an 8TB SDUC card was announced following earlier 4TB SDUC card sightings.

The SDUC Standard: Technical Framework and Goals

The SDUC standard represents a significant expansion of the SD card's capabilities, primarily focused on increasing storage capacity and enhancing data transfer speeds.

SDUC promised 128TB memory cards: The engineering wall keeping SD cards at 2TB - 3

  • Capacity Expansion: SDUC moves the theoretical maximum storage capacity from 2TB (SDXC) to 128TB. This is achieved by extending the addressing capabilities within the standard.

  • File System: SDUC cards utilize the exFAT file system, which is also used by SDXC cards, allowing for larger file sizes and volumes.

  • SD Express Integration: The SDUC standard is closely linked with SD Express, which incorporates PCI Express (PCIe) and NVMe interfaces. This aims to bring SSD-like speeds to SD cards, with transfer rates potentially reaching 985 MB/s.

  • Backward Compatibility: Innovations in the SD 7.0 specification, including SDUC and SD Express, are designed to maintain backward compatibility with existing SD host devices. However, new drivers may be required for hosts to fully support SDUC, particularly for the extended address bits and command sequences.

Reported Availability vs. Consumer Access

While the SD Association states that multi-terabyte SDUC cards are "already shipping," pinpointing their widespread availability for the average consumer proves difficult.

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SDUC promised 128TB memory cards: The engineering wall keeping SD cards at 2TB - 4

  • Official Statements: The SD Association asserts that multi-terabyte SDUC cards are shipping across various sectors.

  • Showcased Prototypes: Companies like SanDisk (Western Digital) have demonstrated 4TB SDUC cards and, more recently, an 8TB SDUC card has been announced.

  • Market Reality: Despite these announcements, these high-capacity cards remain largely absent from common retail listings. Even 2TB SD cards are relatively rare, suggesting a substantial gap between the SDUC specification and mass-market products.

  • Targeted Use Cases: The need for such large capacities is often linked to demanding applications like storing 8K video files, massive photo libraries, or professional video production. This implies that initial shipments might be directed towards specialized professional markets rather than general consumer electronics.

Technological Hurdles and Cost Considerations

The transition from theoretical capacity to commercially viable products involves overcoming significant technical and economic challenges.

  • Manufacturing Complexity: Producing memory chips with such high densities is complex. The "engineering wall" may relate to the difficulties in creating reliable and affordable NAND flash memory at the 128TB scale within the physical constraints of an SD card.

  • Cost-Prohibitive Nature: The cost of manufacturing SD cards with massive storage capacities is acknowledged as a barrier. Reports suggest that a 128TB Express card would likely be extremely expensive, potentially costing more than a vehicle.

  • Compatibility and Drivers: For devices to utilize SDUC cards, their drivers must be updated to handle the new command sequences. Without proper driver support, SDUC cards may not initialize or function correctly.

Expert Insights and Observations

Analysis of the SDUC situation highlights the phased rollout of new technology and the economics of storage.

"The SD Association says multi-terabyte SDUC cards are already shipping, with the format starting at 2TB and scaling up to a theoretical 128TB. The SD Association insists that multi-terabyte SDUC cards are shipping already, although it doesn’t spell out where those products are actually appearing."

This quote from TechRadar points to a discrepancy between official pronouncements and observable market presence.

"Given how slow the progress has been toward 2TB cards, there’s no telling how long it’ll take before manufacturers hit the higher figures that SDUC allows…"

This observation from The Verge in 2018 underscores the gradual pace of technological adoption and manufacturing advancements in achieving high-density storage.

Conclusion and Forward Outlook

The SDUC standard outlines a compelling future for removable storage, with a theoretical capacity of up to 128TB and speeds comparable to SSDs via SD Express. While the SD Association confirms that multi-terabyte SDUC cards are in circulation within certain sectors, these appear to be specialized or early-release products. The delay in widespread consumer availability suggests that significant manufacturing, cost, and potentially compatibility hurdles persist.

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  • Key Findings:

  • The SDUC standard, supporting up to 128TB, was announced in 2018.

  • Prototypes and announcements of 4TB and 8TB SDUC cards have occurred.

  • The SD Association states these cards are "shipping," but specific market locations are unspecified.

  • Consumer availability of high-capacity (even 2TB) SD cards remains limited.

  • Manufacturing costs and complexity are likely reasons for delayed mass adoption.

  • SD Express aims to provide significantly faster data transfer rates alongside higher capacities.

  • Implications: Consumers and professional users requiring massive portable storage will likely continue to rely on external SSDs or specialized storage solutions until the economics and manufacturing processes for 128TB SD cards mature and become broadly accessible. Further advancements in NAND flash technology and cost reduction in manufacturing are critical for the widespread realization of the SDUC standard's full potential.

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Frequently Asked Questions

Q: When were 128TB SD cards first talked about?
The idea for SD cards that could hold up to 128TB, called SDUC, was first shared by the SD Association in June 2018. They also talked about faster speeds with SD Express.
Q: Are 128TB SD cards available to buy now?
The SD Association says that big SDUC cards are being used in some areas. However, it is very hard for regular people to find and buy these cards in stores today.
Q: What is the biggest SD card I can buy easily?
It is hard to find even 2TB SD cards in stores. Companies have shown bigger cards like 4TB and 8TB as examples, but they are not for sale to most people yet.
Q: Why are these super big SD cards not in stores?
Making memory chips that can hold so much data is very hard and costs a lot of money. It is also possible that devices need new software, called drivers, to work with these new cards.
Q: What is the SDUC standard for?
The SDUC standard is made to allow SD cards to hold much more data, up to 128TB, which is a lot. It also works with SD Express to make data transfer much faster, like a small fast drive.