SD cards come in a variety of storage capacities to meet different needs. The most common sizes of SD cards available today are:
SD and SDHC Cards
Original SD cards offer capacities up to 2GB. SDHC (Secure Digital High Capacity) cards are available in capacities between 4GB and 32GB. Both types of cards are the same physical size and will work in SDHC compatible devices. The different classifications refer to the formatting type the cards use.
Common SD and SDHC card sizes include:
SDXC (Secure Digital eXtended Capacity) cards offer capacities between 32GB and 2TB. They use a different file system than SDHC cards, so you need an SDXC compatible device to use them. SDXC cards exceed the storage limits of FAT32 and use the exFAT file system instead.
Common SDXC card sizes include:
SD and SDHC Card Speed Classes
In addition to storage capacity, SD cards are also assigned speed classes to indicate their minimum guaranteed transfer speeds. Speed classes 2, 4, 6, and 10 are commonly seen:
- Class 2 – Minimum write speed of 2MB/s
- Class 4 – Minimum write speed of 4MB/s
- Class 6 – Minimum write speed of 6MB/s
- Class 10 – Minimum write speed of 10MB/s
Higher speed classes allow you to store and retrieve data more quickly, which is important when recording and transferring large files like high resolution photos and video.
SDHC vs. SDXC
The main differences between SDHC and SDXC cards are:
- Storage capacity – SDHC offers up to 32GB, SDXC offers 32GB and above
- File system – SDHC uses FAT32, SDXC uses exFAT
- Compatibility – You need an SDXC compatible device to use the higher capacities
Both types of cards are similarly sized physically and both accept the speed class ratings. Choose SDHC or SDXC based on your device’s compatibility and your storage space needs.
microSD cards are a smaller physical size than standard SD cards. They are often used in smartphones, action cameras, and other small electronics when space is at a premium. The capacities and speed classes available parallel those of full-sized SD cards:
- microSD – Up to 2GB
- microSDHC – 4GB to 32GB
- microSDXC – 32GB and above
You can use a microSD to SD adapter to use a microSD card in an SD compatible device. But standard SD cards will not fit into a microSD card slot.
Full-Size vs. Mini vs. Micro
There are now three physical sizes of SD card available:
- Full-size – 32mm x 24mm x 2.1mm
- Mini – 21.5mm × 20mm × 1.4mm
- Micro – 15mm × 11mm × 1.0mm
Mini cards are less common today, having been largely replaced by microSD. Full-size SD remains the most compatible with different types of devices.
Choosing an SD Card Capacity
Factors to consider when choosing an SD card capacity include:
- Your device’s maximum supported capacity
- The sizes of files you will be storing (photos, videos, music, documents, etc.)
- How much total storage space you need
- Your budget
Higher capacity cards are priced higher than lower capacity cards. Get the smallest size that has enough room to hold the files you need to store. You can use multiple cards if necessary to add more storage space.
Typical usage capacities:
|Basic photo camera, MP3 player storage
|Point & shoot camera, smartphone, game console
|Advanced digital camera, HD video recorder
|512GB and up
|Professional HD video camera
SD Card Speeds
Faster SD card speeds allow you to transfer files to and from the card more quickly. This is especially noticeable when transferring large files like photos, videos, and games. Some common transfer speed classifications are:
- Class 2 – Minimum write speed 2MB/s
- Class 4 – Minimum write speed 4MB/s
- Class 10 – Minimum write speed 10MB/s
- UHS Class 1 – Minimum write speed 10MB/s
- UHS Class 3 – Minimum write speed 30MB/s
High speed cards allow you to take advantage of your device’s capabilities. This allows 4K video recording and burst mode photography. Check your device specs for its SD card speed capabilities.
SD Bus Speeds
In addition to the speed class ratings, SD cards can also be rated by their supported bus interface speeds. This measures the maximum data transfer rate between the card and device:
- SD – Default speed up to 25MB/s
- UHS-I – Up to 104MB/s
- UHS-II – Up to 312MB/s
- UHS-III – Up to 624MB/s
Using a card that matches your device’s bus speed allows you to take full advantage of transfer performance. However, cards with higher bus speeds are backward compatible in most cases.
SD Card Capacities and Prices
As with most storage technologies, SD card prices decline over time as capacities increase. Some typical price ranges as of 2023 are:
|$5 – $20
|$10 – $25
|$15 – $40
|$25 – $70
|$60 – $250
|$100 – $400
You can find excellent deals on some capacity sizes, especially if you shop sales. Prices vary between brands as well, with premium brands commanding slight premiums.
SD Card Considerations
Key factors to consider when selecting an SD card include:
- Storage needs based on your usage
- Device compatibility with SDHC, SDXC, or microSD
- Speed class rating that meets your performance needs
- Bus speed capabilities to maximize transfer speeds
- Reputation and reliability of the memory brand
- Value and affordability based on current pricing
Matching your SD card’s specifications and capacities to your usage needs and device capabilities allows you to select the optimal card for performance, value, and reliability.
SD cards are available in a range of storage capacities, speed ratings, and physical sizes. Choose based on the capabilities of your device and your file storage and transfer needs. SDHC offers capacities up to 32GB, while SDXC starts at 32GB but can offer up to 2TB of storage. Speed classes indicate the minimum guaranteed read and write speeds, while bus ratings measure maximum interface transfer rates.
Higher capacities allow you to store more photos, video, music, game files, and apps. Faster speeds enable smooth 4K recording and playback as well as quick file transfers. Select the right combination of size, speed, and value to get the most out of your SD card and compatible devices.