Nikon Z6 II Memory Card Guide: Dual-Slot Limits & CFexpress Speeds

The Nikon Z6 II has two memory card slots. Unlike the original Z6, which relied on a single slot, the Mark II provides the redundancy and flexibility that professional workflows demand.

However, because the two slots use entirely different technologies (CFexpress Type B and SDXC UHS-II), choosing the right combination of cards is essential to avoid bottlenecking the camera’s performance. Here is a practical look at exactly how I manage this dual-slot system, navigate the shifting CFexpress market, and buy cards fast enough to handle the Z6 II’s 14 fps burst rate without overpaying.

Which Z6 Generation are you shooting?

This guide covers the dual-slot Nikon Z6 II. If you’re using a different model of Z6, the card slots and speed limits are completely different. For the original Z6 and the newer Z6 III, see my dedicated guides here:
– Nikon Z6 III Memory Card Recommendations (6K RAW & VPG400 Support)
– Nikon Z6 Memory Card Recommendations (Original Single-Slot Model)

Quick recommendations

• Slot 1 (Primary): CFexpress Type B (Preferred) or XQD
• Slot 2 (Secondary): SDXC V90 UHS-II
• Workflow Essential: Dual-Slot CFexpress B / SDXC Reader

Nikon Z6 II card types & slot compatibility

Slot 1 takes a CFexpress Type B or XQD card, and Slot 2 takes an SD card with UHS-II support. The Z6 II is a versatile hybrid camera, and to get the most out of the dual EXPEED 6 processors, the 14 fps RAW burst rate, and high-bitrate 4K video, you need to understand the physical limits of each slot.

For video shooters, Nikon explicitly states that for recording 4K/60p, you need a card with a sustained transfer rate of at least 250 MB/s. Slower cards will cause the recording to drop frames or stop abruptly.

Slot 1: CFexpress Type B & the 4.0 opportunity

Slot 1 is the high-performance engine of the camera. It accepts both CFexpress Type B and legacy XQD cards. While the physical form factor is identical, CFexpress is the modern standard, offering vastly superior speeds that will clear your 24.5-megapixel RAW bursts almost instantly.

One thing worth clearing up, because it trips people up: the Z6 II does not need a firmware update to use CFexpress Type B. That was the original Z6 and Z7, which shipped as XQD-only cameras and only gained CFexpress support later through firmware. The Z6 II handled both formats from launch, so a CFexpress Type B card works in Slot 1 straight out of the box.

Note on Types: CFexpress comes in three sizes (A, B, and C). The Z6 II only accepts Type B. Do not buy Type A (used by Sony) or the oversized Type C. Similarly, CFast cards are an entirely different format and will not fit.

Should you buy a CFexpress 4.0 card for the Z6 II?

The CFexpress market is currently transitioning from the older 2.0 spec to the newer, twice-as-fast 4.0 spec. Because the cards look identical, navigating this shift is actually a great opportunity to save some cash if you know what to look for.

The Nikon Z6 II is a CFexpress 2.0 camera. It physically lacks the PCIe Gen 4 hardware required to hit the newer 4.0 speeds. This is a hardware limitation that cannot be changed with a firmware update.

Because the CFexpress standard is backward compatible, you can put a bleeding-edge 4.0 card into the Z6 II, and it will work flawlessly. The camera simply throttles that card down to 2.0 speeds. While you won’t see an in-camera performance bump from a 4.0 card, this backward compatibility opens up some opportunities for smart buying.

In a perfectly logical market, you’d just buy the cheapest 2.0 card you could find. But it’s not that simple. Because manufacturers are aggressively shifting their production lines to the new standard, newer 4.0 cards are sometimes actually cheaper and more readily available than the legacy 2.0 cards they replaced. In a market distortion due to algorithmic pricing based on the limited availability of legacy stock, I’ve even seen older 2.0 cards show up at massively inflated prices that are more expensive than the newer, faster 4.0 replacements.

So, my rule of thumb is to look at the sustained write speeds and go with whatever is cheaper, regardless of whether the label says 2.0 or 4.0. If you spot a 4.0 card for the same price or cheaper than its 2.0 equivalent, grabbing the newer version is a fantastic win. You keep extra money in your pocket today, and as a bonus, you unlock drastically faster desktop offload speeds when you get back to your desk (provided you pair it with a USB 4.0 memory card reader).

Here are excellent, reliable options for the Z6 II that easily clear the camera’s 250 MB/s requirement without making you overpay for cinema-level speeds you don’t need:

Slot 2: SDXC & the dual-slot bottleneck trap

The second slot utilizes standard SDXC cards. Because the Z6 II produces large 24.5MP RAW files and high-bitrate 4K video, I highly recommend using UHS-II cards here to keep your workflow moving.

More importantly, you have to be careful how you configure the camera’s menus. If you set Slot 2 to Backup Mode (writing duplicate RAW files to both cards simultaneously for an instant backup), the camera cannot clear its internal buffer until the photo is written to both locations.

If you pair a lightning-fast CFexpress card in Slot 1 with a slow UHS-I SD card in Slot 2, the entire camera will instantly throttle to the speed of the SD card. Your 14 fps burst will hit a wall almost immediately. To maximize the Z6 II’s performance in dual-write scenarios, my independent memory card speed tests point to pairing your CFexpress card with a high-speed V90 UHS-II SDXC card.

That penalty only applies when the camera is writing to both cards at once. Set Slot 2 to Overflow instead and the camera fills the CFexpress card first, only switching to the SD card when the first one runs out of room, so a slower SD card doesn’t hold up the buffer during a burst. Backup is the mode where the SD card’s write speed becomes your ceiling.

Heads up! Don’t buy an SD Express card. The Z6 II lacks the internal hardware to utilize the emerging SD Express standard. While they will physically fit, they will default to sluggish UHS-I speeds, wasting your money. Stick to standard UHS-II SDXC cards.

The golden rule & formatting quirks

My golden rule for storage media is to always format the memory card directly inside the camera before a shoot, rather than relying on your computer to do it. You can format either slot by navigating to the yellow Setup Menu (Wrench Icon) and selecting Format memory card.

The Formatting Quirk: When formatting cards in the Z6 II’s menu system, the two slots are listed as CFexpress/XQD card slot and SD card slot. Slot 1 keeps the XQD name alongside CFexpress because the one slot takes both formats, and it makes no difference to how the card performs.

If you accidentally format the wrong card in the field, stop shooting immediately. Because the camera only performs a high-level format that wipes the directory index, you can usually recover your deleted photos later, as long as you haven’t written new files over the old data.

If your memory card begins to act sluggishly or throws read errors after months of heavy use, a standard in-camera format might not be enough. In that case, I recommend connecting the card to your computer and executing a full format instead of a quick format using a dedicated utility tool to deeply restore the flash memory.

Memory card readers

Your old XQD reader likely will not read CFexpress B cards, even though the slot looks identical, unless the reader’s hardware was explicitly designed to be cross-compatible.

In my workflow, I prefer to ingest both slots simultaneously without taking up multiple ports on my computer. I highly recommend a dual-slot reader that handles both CFexpress B and UHS-II SD cards in a single Thunderbolt 3 or USB-C connection.