You’ve invested thousands in a powerful mirrorless camera capable of incredible 8K video and lightning-fast burst shooting. But that potential is useless if it’s choked by the wrong memory card—an accessory that has become one of the most critical and confusing purchasing decisions for any serious creative in 2025.
The high-speed memory market is a complex battleground: the compact CFexpress Type A, the powerhouse CFexpress Type B, and the perpetually-on-the-horizon SD Express. Choosing incorrectly doesn’t just mean slower offload times; it means missed shots, failed video recordings, and a camera that can’t perform at its peak.
This definitive guide cuts through the marketing noise. Using real-world performance benchmarks, a detailed price-per-gigabyte analysis, and our interactive Value Matrix, we will show you exactly which card offers the best performance and value for your specific camera and workflow—whether you’re a Sony, Canon, Nikon, or Fujifilm shooter.
The Professional's Guide to High-Speed Memory
A data-driven analysis of CFexpress Type A, Type B, and SD Express for today's mirrorless cameras. Stop guessing, start investing smarter.
1. Deconstructing the Standards
The performance leap in modern memory cards comes from adopting PC-grade technology: the **PCIe bus** for data transfer and the **NVMe protocol** for low-latency communication. But key differences in size, data lanes, and design create a complex landscape for professionals.
CFexpress Type A
20x28mm
PCIe Lanes: x1
Max Speed (2.0): 1,000 MB/s
Max Speed (4.0): 2,000 MB/s
CFexpress Type B
38.5x29.8mm
PCIe Lanes: x2
Max Speed (2.0): 2,000 MB/s
Max Speed (4.0): 4,000 MB/s
SD Express
32x24mm
PCIe Lanes: x1 (x2 rare)
Max Speed (SD 7.0): ~1,000 MB/s
Max Speed (SD 8.0): ~4,000 MB/s
Key Differentiators Beyond Raw Speed
Heat Dissipation
Performance generates heat. The larger, metal-housed CFexpress Type B card has a significant advantage, acting as a heat sink to prevent thermal throttling during intense tasks like 8K RAW video recording. Smaller, plastic-housed cards have less thermal mass.
Performance Ratings (VPG)
Don't be fooled by "Max Speed." Look for the **Video Performance Guarantee (VPG)** rating on CFexpress cards. A VPG400 rating guarantees the card's write speed will never drop below 400 MB/s, a vital assurance for high-bitrate video.
The SD Express Backward Compatibility Crisis
A critical design flaw has stalled SD Express adoption in cameras. To enable PCIe, it reassigns pins used by the fast UHS-II bus. When an SD Express card is put in a UHS-II slot (the pro standard), it falls back to the ancient, slow UHS-I bus (~104 MB/s), making it slower than the card it's meant to replace. This has effectively blocked its adoption by camera makers.
2. The Ecosystem: Who Supports What?
Camera manufacturers have placed their bets, creating distinct, incompatible ecosystems. Your camera choice dictates your high-speed memory investment. Filter the table below to see where your gear fits.
| Manufacturer | Model | Slot 1 | Slot 2 |
|---|
Sony's Hybrid Slot Advantage
Sony's masterstroke is the hybrid slot. Since CFe-A cards are smaller than SD cards, their slots can accept either format. This gives users incredible flexibility, allowing them to use existing SD cards and only invest in expensive CFe-A cards when absolutely necessary.
Nikon's XQD Upgrade Path
CFe-B cards are physically identical to older XQD cards. This allowed Nikon to provide a seamless upgrade path for users of cameras like the Z6/Z7. A simple firmware update enables support for the newer, faster, and more widely available CFe-B format.
3. Real-World Performance Benchmarks
Theoretical speeds are for marketing. Sustained write speed—the speed after the card's internal cache is full—is what truly matters for clearing buffers and recording high-bitrate video. We've compiled independent test data to show you the real performers.
CFexpress Type A: Sustained Write Speeds
CFexpress Type B: Sustained Write Speeds
4. The Workflow Impact: From Capture to Offload
A card's performance directly impacts every stage of your workflow. Here's what you need to know about video bitrates, buffer clearing, and getting your files onto your computer.
Video Bitrates vs. Card Speed
For video, your card's sustained write speed MUST exceed the camera's video bitrate to avoid dropped frames. This table shows the minimum required speeds for common professional formats.
| Video Format | Bitrate (Mbps) | Required Write Speed (MB/s) | Min. Card Rating |
|---|---|---|---|
| 4K UHD (10-bit, 60p) | ~400 Mbps | 50 MB/s | V60 |
| Canon 4K 120p ALL-I | ~1880 Mbps | 235 MB/s | V90 / VPG200 |
| Canon 8K RAW Light (30p) | ~2600 Mbps | 325 MB/s | VPG400 CFe |
| Nikon N-RAW 8.3K 60p | ~6800 Mbps | 850 MB/s | High-Perf CFe-B |
The Dual-Slot Bottleneck
Warning for mixed-slot camera users (CFe-B + SD): When writing backups to both cards, your speed is limited by the slowest card. Your 1500 MB/s CFexpress card is forced to wait for the 250 MB/s SD card. You must choose: max speed or backup security.
The Offload Bottleneck
To get the full offload speed from a CFexpress 4.0 card, your reader and computer port must support USB4 or Thunderbolt (40Gbps). Using a standard USB 3.2 reader (10Gbps) will cap your transfer speeds at around 1,250 MB/s, no matter how fast your card is.
5. The Price/Performance Value Matrix
This is where it all comes together. We've calculated the cost per gigabyte ($/GB) and, more importantly, the **cost per unit of sustained performance ($/MB/s)**. This "Value" score is the ultimate metric for finding the most cost-effective speed. Filter by card type and sort the columns to find the absolute best value for your needs.
| Card | Type | Sustained Write (MB/s)▼ | Price ($) | $/GB | $/MB/s (Value) |
|---|
6. Final Recommendations
The optimal choice depends on your camera, workflow, and budget. Here's our synthesis.
Verdict for the Sony User (CFe Type A)
Max Performance (a1, a9 III, 8K Video):
CFe Type A is non-negotiable for unlocking top video codecs and clearing the buffer instantly. Based on our value matrix, the Wise 1TB CFexpress 4.0 Mk-II offers the best value for top-tier performance.
General Pro Use (a7R V, Standard 4K):
A high-quality V90 UHS-II SD card is more cost-effective and sufficient for most stills and standard 4K work. Start with a fast SD card like the Delkin Power V90 and upgrade to CFe-A only when a project's demands exceed its capabilities.
Verdict for Canon, Nikon & Co. (CFe Type B)
Max Performance (Z9, R5, 8K RAW):
A top-tier CFe-B card is essential. The ProGrade Gold 1TB 2.0 and Lexar Gold 1TB/2TB 2.0 are standout values. To avoid bottlenecks in mixed-slot cameras, record to the CFe card alone for critical high-speed work.
Budget-Conscious / Backup:
The SanDisk Extreme 128GB is an excellent, low-cost entry point for enabling dual-slot functionality or for less demanding workflows. It provides a significant speed boost over any SD card without a huge investment.
Strategic Purchasing Checklist
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1
Identify Your Camera Slot(s): Know your hardware. This defines your options.
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2
Define Your Performance Need: What's your most demanding task? 8K RAW? 30fps bursts? This sets your minimum required sustained write speed.
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3
Consult the Value Matrix: Filter our interactive table for cards that meet your needs.
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4
Select the Best Value: Choose the card with the lowest $/MB/s (Value) score that fits your budget.
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5
Don't Forget the Reader: To unlock max offload speeds, pair a CF 4.0 card with a USB4/Thunderbolt reader.
