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1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteSD, SDHC, SDXC and SDUC are capacity standards; SD, miniSD and microSD describe physical sizes. A card is usable only when both its capacity family and physical format are supported by the host device. Speed-class symbols and bus labels add performance requirements, but they do not override compatibility.
Before buying, read the camera, phone, console or computer manual and match its SD logo or stated card type. The SD Association’s practical rule is: “Match the Logo to your device”.
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What SD, SDHC, SDXC and SDUC mean
The letters after SD identify a capacity family and its required file system. They are not different plug shapes. The ranges below are standards-defined limits from the SD Association; they do not mean every capacity is sold or that every host can use the full range.
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| Family | Standards capacity range | Typical file system required by the standard | Compatibility implication |
|---|---|---|---|
| SD | Up to 2GB | FAT12 or FAT16 | Works in SD, SDHC, SDXC and SDUC hosts when the physical format fits |
| SDHC | Over 2GB through 32GB | FAT32 | Requires an SDHC-or-newer host |
| SDXC | Over 32GB through 2TB | exFAT | Requires an SDXC-or-newer host |
| SDUC | Over 2TB through 128TB | exFAT | Requires an SDUC host |
“SD” is therefore ambiguous in casual product descriptions. A device advertised as having an “SD slot” may support only original SD cards, or it may also list SDHC and SDXC. The family printed on the card and the family listed in the device documentation must agree.
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- Save time with card offload speeds of up to 200MB/s powered by SanDisk QuickFlow Technology (Up to 200MB/s read speeds, engineered with proprietary technology to reach speeds beyond UHS-I 104MB/s, require compatible devices capable of reaching such speeds. Based on internal testing; performance may be lower depending upon host device, interface, usage conditions and other factors. 1MB=1,000,000 bytes. X = 150KB/sec. SanDisk QuickFlow Technology is only available for 64GB, 128GB, 256GB, 512GB and 1TB capacities. 1GB=1,000,000,000 bytes. 1TB=1,000,000,000,000 bytes. Actual user storage less.)
- Pair with the SanDisk Professional PRO-READER SD and microSD to achieve maximum speeds (sold separately)
- Shot speeds up to 140MB/s (Write speed up to 140MB/s. Based on internal testing; performance may be lower depending upon host device, interface, usage conditions and other factors. 1MB=1,000,000 bytes. X = 150KB/sec.)
- Perfect for shooting 4K UHD video and sequential burst mode photography (Full HD (1920x1080) and 4K UHD (3840 x 2160) video support may vary based upon host device, file attributes and other factors. See HD page on SanDisk site.)
- UHS Speed Class 3 (U3) and Video Speed Class 30 (V30) (UHS Speed Class 3 designates a performance option designed to support 4K UHD video recording with enabled UHS host devices. UHS Video Speed Class 30 (V30), sustained video capture rate of 30MB/s, designates a performance option designed to support real-time video recording with UHS enabled host devices. See the SD Association’s official website.)
Host and card compatibility
The SD Association’s compatibility guidance is hierarchical: newer host standards accept older card families, but an older host does not automatically understand a newer family.
| Host marked for | Card families it accepts |
|---|---|
| SD | SD only |
| SDHC | SD and SDHC |
| SDXC | SD, SDHC and SDXC |
| SDUC | SD, SDHC, SDXC and SDUC |
Viewed from the card side, an SD card can be used in any of those hosts; an SDHC card needs an SDHC, SDXC or SDUC host; an SDXC card needs an SDXC or SDUC host; and an SDUC card needs an SDUC host. This is why an SDXC card can be electrically the right shape yet fail in an older camera that supports only SDHC.
How to verify a device before purchase
- Look for the SD, SDHC, SDXC or SDUC logo printed beside the slot or in the specifications.
- Read the manual’s memory-card section, including any maximum capacity or firmware qualification.
- Check the manufacturer’s support page for the exact model, because two devices with similar slots can support different families.
- Confirm the required speed class and bus interface as well as capacity.
- If the device has no published support for a family, treat that family as incompatible rather than relying on the connector alone.
Physical sizes: SD, miniSD and microSD
Physical form factor is independent of capacity family. An SDXC card can be full-size SD or microSDXC; the “XC” describes capacity, while the size describes whether it physically enters the slot.
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|---|---|---|
| Standard SD | 32 × 24 × 2.1mm | Largest common SD form factor; normally has a mechanical write-protect switch |
| microSD | 11 × 15 × 1.0mm | Much smaller; no standard-size write-protect switch on the card itself |
| miniSD | Not stated in the cited specifications | Different dimensions, pin arrangement and switch design from standard SD |
The SD Association notes that miniSD and microSD differ from standard SD in form factor, size, number of pins and the presence or absence of a write-protect switch. Do not infer a card’s capacity family from its size: SD, SDHC, SDXC and SDUC versions exist in more than one form factor.
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- CAPTURE LARGER THAN LIFE. Unlock 4K UHD(3) brilliance and pristine high res stills with video speed class ratings of U3 and V30(4).
- SPEED BARRIERS SHATTERED. Save precious moments with blazing read speeds up to 250MB/s(2) and write speeds up to 170MB/s(2) [256GB-1TB capacities(1)].
- MAXIMIZE WITH MASSIVE CAPACITY. Capture for longer and store more with up to 2TB(1) of storage that can hold up to 2,808 minutes of 4K UHD video recorded at 30 fps (641MB/minute)(9).
- DEFY THE ELEMENTS. Unrelentingly resilient, Sandisk SD memory cards are engineered to perform in extreme conditions, despite rough handling and constant use.(6)
- CONTENT MANAGEMENT, SIMPLIFIED. Back up, organize, and transfer everything easily with the Sandisk Memory Zone desktop app,(7) whether you use an SD card slot or a card reader.
Using a microSD card in a full-size SD slot
A passive microSD-to-SD adapter changes the card’s physical shape and exposes the required contacts. It does not convert an SDHC card into SDXC, add a faster bus, or make an unsupported capacity family readable. The host must support the microSD card’s standard, and the adapter must be correctly wired.
Insert the microSD card into the adapter in the orientation shown by the adapter, then insert the adapter into the host without force. If the device manual does not list microSD through an adapter, compatibility is not guaranteed. A damaged, low-quality or write-protected adapter can also cause intermittent detection even when the card family is supported. Sony’s support guidance likewise advises matching the camera’s supported card and bus specifications: camera card compatibility guidance.
Speed classes and bus interfaces are different
A speed-class symbol states a minimum sequential-access performance category under conditions defined by the relevant standard. A bus label identifies the electrical interface and its theoretical transfer capability. A card can have a high bus rating but a lower write-performance class, and a fast card cannot make a host use a bus it does not support.
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Speed-class systems
The SD Association defines Speed Class, UHS Speed Class, Video Speed Class and SD Express Speed Class. The number in each symbol represents a minimum performance category for the corresponding system, useful when a camera requires a sustained recording rate. The systems are not interchangeable merely because their symbols contain the same number. Use the exact class symbol requested in the host manual.
Rank #3
- Save time with card offload speeds of up to 200MB/s powered by SanDisk QuickFlow Technology (Up to 200MB/s read speeds, engineered with proprietary technology to reach speeds beyond UHS-I 104MB/s, require compatible devices capable of reaching such speeds. Based on internal testing; performance may be lower depending upon host device, interface, usage conditions and other factors. 1MB=1,000,000 bytes. X = 150KB/sec. SanDisk QuickFlow Technology is only available for 64GB, 128GB, 256GB, 512GB and 1TB capacities. 1GB=1,000,000,000 bytes. 1TB=1,000,000,000,000 bytes. Actual user storage less.)
- Pair with the SanDisk Professional PRO-READER SD and microSD to achieve maximum speeds (sold separately)
- Shot speeds up to 90MB/s (Write speed up to 90MB/s. Based on internal testing; performance may be lower depending upon host device. 1MB=1,000,000 bytes. X = 150KB/sec.)
- Perfect for shooting 4K UHD video and sequential burst mode photography (Full HD (1920x1080) and 4K UHD (3840 x 2160) video support may vary based upon host device, file attributes and other factors. See HD page on SanDisk site.)
- UHS Speed Class 3 (U3) and Video Speed Class 30 (V30) (UHS Speed Class 3 designates a performance option designed to support 4K UHD video recording with enabled UHS host devices. UHS Video Speed Class 30 (V30), sustained video capture rate of 30MB/s, designates a performance option designed to support real-time video recording with UHS enabled host devices. See the SD Association’s official website.)
The SD Association states: “All speed class types assures minimum sequential card access performance including multiple stream access (in SD Express Speed Classes) under defined conditions specified by the standard.” Read the full definitions at the SD Association Speed Class page.
Bus-interface labels
| Interface | Theoretical bus rate listed by the SD Association | What the figure does not promise |
|---|---|---|
| UHS-I | Up to 104MB/s | Actual card read or write speed |
| UHS-II | Up to 312MB/s half-duplex, or 156MB/s full-duplex | That every UHS-II card or host reaches the maximum |
| UHS-III | Up to 624MB/s | Sustained recording performance without a matching speed class |
| SD Express | Up to 3940MB/s | Performance on a host that lacks SD Express support |
These are interface maxima, not guaranteed transfer speeds. The card and host negotiate the fastest mode they both support, and firmware, file size, workload and the card’s own controller affect results. A UHS-II card in a UHS-I-only camera can operate at the lower interface level; it does not upgrade the camera.
Choosing a speed requirement
- For still photography, check the camera’s stated card class and bus support, especially if burst shooting must clear quickly.
- For video, follow the required Video Speed Class or other sustained-write specification rather than judging by a marketing read-speed figure.
- For data transfer to a computer, both the card reader and computer interface must support the desired bus; otherwise the slower component limits throughput.
Application Performance Class A1 and A2
A1 and A2 markings concern random as well as sequential performance for running applications from a card. They matter mainly for phones, tablets, cameras or other hosts that install applications or application data on removable storage.
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An A2 card needs an A2-capable host to deliver A2 performance. The logo alone does not make an older host perform at A2 levels. If the device is used only for photos, video or file transfer, the recording speed class and bus interface are usually more relevant than A1/A2.
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- Fast for better pictures and Full HD video. Full HD (1920x1080) video support may vary based upon host device, file attributes, and other factors
- Great choice for compact to mid-range point-and-shoot cameras
- From 32GB to 256GB(1) to store tons of pictures and even more Full HD video(2). (1)1GB=1,000,000,000 bytes Actual user storage less
- Exceptional video recording performance with UHS Speed Class 1 (U1)(5) and Class 10 rating for Full HD video (1080p)(2). (5)UHS Speed Class 1 (U1) designates a performance option to support real time video recording with UHS enabled host devices
- Quick transfer speeds up to 100MB/s. Up to 100MB/s[64GB-256GB; 90MB/s for 32GB] read speed; write speed lower Based on internal testing; performance may be lower depending on host device, usage conditions, and other factors 1MB=1,000,000 bytes
See the specification details at the SD Association’s Application Performance Class page.
SD formatting and why it cannot fix incompatibility
Formatting creates a file system and directory structure; it does not change the card’s capacity family, pin layout, controller or bus interface. Reformatting an SDXC card as FAT32, for example, does not turn an SDHC-only camera into an SDXC host, and it may remove the file system the card standard expects.
- Back up every file before formatting; formatting erases the card.
- Use the device’s own format command when its manual specifies one.
- For SD, SDHC and SDXC media, the SD Association recommends its formatter over generic operating-system formatters: formatting and compatibility guidance.
- After formatting, eject the card safely and test a real recording or file copy, not just whether the card appears in a menu.
If the host reports an unsupported card, formatting is not the first remedy. Verify the family and maximum capacity in the manual, test a card explicitly listed by the manufacturer, and check for a firmware update documented for that model.
CFexpress, CFast, XQD and CompactFlash are separate formats
CFexpress, CFast, XQD and CompactFlash are not larger or faster versions of SD. The CompactFlash Association treats each as its own removable-media standard, with separate physical and interface specifications. They do not fit an SD slot, and an SD adapter cannot make them interchangeable.
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- Great choice for compact to mid-range point-and-shoot cameras
- Quick transfer speeds up to 140MB/s (Up to 140MB/s read speed engineered with proprietary technology to reach speeds beyond UHS-I 104MB/s, requires compatible devices capable of reaching such speeds. Based on internal testing; performance may be lower depending on host device, interface, usage conditions and other factors. 1MB=1,000,000 bytes.)
- Up to 128GB to store tons of pictures (1GB=1,000,000,000 bytes. Actual user storage less.)
- Exceptional video recording performance with UHS Speed Class 1 (U1) Class 10 rating for Full HD video (1080p) (UHS Speed Class 1 (U1) designates a performance option designed to support real time video recording with UHS enabled host devices. See consumers speed page on SanDisk site. Full HD (1920x1080) video support may vary based upon host device, file attributes, and other factors. Visit the SanDisk Video Knowledge Base for more information.)
- Compatible with SanDisk SD UHS-I card reader (sold separately)
| Format | Relationship to SD | How to determine support |
|---|---|---|
| CFexpress | Independent professional removable-media format | Check the exact card type/version and camera or recorder model |
| CFast | Independent format with its own interface | Use only in a host that explicitly lists CFast |
| XQD | Independent format and connector | Confirm XQD support for the specific device |
| CompactFlash | Independent format with its own specifications and versions | Match the host’s CompactFlash specification |
Some cameras provide more than one slot type, but that is a feature of that particular host, not evidence that the formats share compatibility. The CompactFlash Association card-types overview lists these standards.
A practical card-selection checklist
- Identify the physical slot. Decide whether the host takes standard SD, microSD or another format. An adapter is an option only when the manual permits it.
- Identify the capacity family. Match SD, SDHC, SDXC or SDUC exactly. Treat a stated maximum capacity as a host limit, not a suggestion.
- Check the file-system expectation. SDHC normally uses FAT32; SDXC and SDUC use exFAT under their standards. Do not reformat solely to bypass a family mismatch.
- Match sustained performance. For recording, choose the speed-class system and minimum class named by the host.
- Match the bus. Compare UHS-I, UHS-II, UHS-III or SD Express support on both sides. A higher card rating is backward-compatible only at the host’s supported level.
- Confirm the workload. Application storage may justify A1 or A2; ordinary file storage may not.
- Buy from a source with returns and test immediately. Copy representative files, record at the intended resolution and duration, and verify playback before relying on the card.
Common compatibility problems and fixes
The card is physically too large or too small
Never force a card into a slot. Use the correct form factor or a passive adapter approved for that host. If the card is detected but disconnects when moved, replace the adapter and inspect the contacts.
The camera says “card not supported”
Compare the card’s SD, SDHC, SDXC or SDUC logo with the camera manual. An SDXC card in an SDHC-only camera is a standards mismatch, not a formatting problem. If the family is correct, check the required speed class, maximum capacity and documented firmware version.
Recording stops or drops frames
Check the minimum sustained speed class first, then confirm that the host and card share the same bus mode. A high advertised read speed does not substitute for the required write class. Test with a card that meets or exceeds the exact specification rather than relying on a generic “fast” label.
A computer reads the card slowly
The limiting component may be the reader, USB connection, host bus or card. A UHS-II or SD Express card cannot deliver its interface maximum through a UHS-I reader. Use a reader that explicitly supports the card’s bus and connect it through a port capable of that reader’s interface.
The card works in one device but not another
That result is normal when the devices implement different capacity families, speed classes, bus interfaces or file-system support. Compare both manuals; compatibility is host-specific, even when the slots look identical.
The decision in one sentence
Choose a card by matching, in order, the host’s physical slot, capacity family, required speed class, supported bus and workload. The exact device manual outranks a retailer’s generic “SD-compatible” wording, and a connector or adapter alone cannot establish compatibility.
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