SDHC vs SDXC:

Which Memory Card Standard Do You Need? 

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SDHC vs SDXC Comparison: Capacity, Speed, & Compatibility

Comparing Capacity, Speed & Compatibility

SDHC vs SDXC

SDHC™ (Secure Digital High Capacity) and SDXC™ (Secure Digital Extended Capacity) are capacity standards, or classes, for memory cards. These determine maximum storage limits, file organization systems, and device compatibility for your SD card. This guide will cover SD card capacity classes, their respective file systems, device compatibility, optimal use-cases, and how card capacity impacts performance.

Looking for more general information about SD cards and the technology that powers them? Click here.

SDHC vs SDXC at a Glance

Feature / Standard SDHC (High Capacity) SDXC (eXtended Capacity)
Capacity boundary  Above 2GB up to 32GB Above 32GB up to 2TB
Default file system FAT32 exFAT
Max individual file size ~4GB (4 GiB) per file 16 exabytes - no practical cap
Host device compatibility Works in SDHC, SDXC and SDUC hosts Requires an SDXC- or SDUC-compatible host
Typical use 1080p video, everyday photos, legacy and budget devices 4K/8K video, RAW burst photography, long-form recording
Form factors  SD and microSDHC SD and microSDXC

Under the SD standard, SDHC covers capacities above 2GB through 32GB and uses FAT32, while SDXC covers capacities above 32GB through 2TB and uses exFAT1. Additionally, the capacity class has no impact on a card’s form factor, speed class, or bus interface.

What Are SDHC and SDXC Cards?

SDHC and SDXC cards are two capacity standards for memory cards. SDHC cards range from 2GB to 32GB and use the FAT32 file system, while SDXC cards range from 32GB and 2TB and use the exFAT file system1. These standards apply to SD and microSD™ cards.

Example of an SDHC sd card

SDHC Cards

  • 2GB - 32GB
  • 4GB individual size limit2
  • Compatible with SDHC, SDXC, and SDUC™ devices
  • Ideal for 1080p, everyday photography, and legacy devices.
Example of an SDXC sd card

SDXC Cards

  • 32GB - 1TB
  • Effectively no file size limit2
  • Compatible with SDXC and SDUC devices
  • Ideal for 4K/8K video, RAW-burst photography, and long-form recording.

What Is SDHC?

SDHC, or Secure Digital High Capacity, is the second generation of capacity standards set forth by the SD Association, replacing SDSC (Secure Digital Standard Capacity). SDHC cards have capacities between 2GB and 32GB and use the FAT32 file system1. SDHC cards are ideal for point-and-shoot and entry level photography, 1080p full HD video, and vintage digital cameras.

Importantly, because of the FAT32 file system, SDHC cards cap individual files at 4GB.

What Is SDXC?

SDXC, or Secure Digital Extended Capacity, is the third generation of capacity standards established by the SD Association. SDXC cards have capacities between 32GB and 2TB and use the exFAT file system. SDXC cards are ideal for 4K and 8K video, continuous RAW burst photography, drones, and action cameras3.

Unlike SDHC, there’s effectively no limit on individual file sizes, making SDXC cards ideal for dense, high-bitrate data capture.

SD vs SDHC vs SDXC vs SDUC: The Full Capacity Ladder

There are four capacity standards for SD and microSD™ cards: SD, SDHC, SDXC, and SDUC. See the chart below to get a sense of their capabilities and use-cases1.

Generation Capacities File System Device Compatibility Use-case
SD (or SDSC) Up to 2GB FAT12 or FAT16 All host devices Legacy devices
SDHC 2GB – 32GB FAT32 SDHC, SDXC, and SDUC host devices Casual photography, entry level video recording
SDXC 32GB – 2TB exFAT SDXC and SDUC host devices 4K/8K recordings, RAW burst photography
SDUC 2T – 128TB exFAT SDUC host devices only. Future-proof data storage for professionals

For most users, SDHC and SDXC are the sweet spot. SDSCTM cards are a legacy standard, perfect for retro devices but not ideal for modern demands, while SDUC cards are the future of SD card technologies.

In terms of backwards compatibility, host devices are compatible with the capacity standard it’s rated for, as well as the previous generations. In practice, this means an SDXC memory card reader can read SDSC, SDHC, and SDXC cards, but not SDUC cards.

Types of SD and microSD Cards: Form Factors and Adapters

SD and microSD™ cards are form factors, different physical dimensions for the same underlying technology. Full-sized SD cards are 32mm by 24mm while microSD cards are 15mm by 11mm4.

Form factor has no influence on the technical parameters of a memory card; a microSDXC card will have the same capacity boundaries and file systems as its full-size SDXC counterpart. Because the only difference in the cards is their physical shape and size, users can use passive adapters to allow microSD cards to work in full-sized SD card slots.

A passive adapter is electrically transparent and does not, by itself, change a card's rated speed class; a microSD card in an adapter performs to the limits of the card, the adapter, and the host together. The one real specification limit worth stating: a UHS-II microSD card used in a standard SD adapter falls back to UHS-I speeds, because the adapter does not carry the second row of pins.

Many traditional cameras leverage full-size SD cards, while several smaller devices like handheld gaming consoles, action cameras, drones, smartphones, tablets, and dash cams rely on the smaller form factor of the microSD card.

Compatibility: Will an SDXC Card Work in an SDHC Device?

No, an SDXC card will not work with an SDHC device. An SDXC card requires an SDXC- or SDUC- compatible host device; an SDHC card works in SDHC, SDXC and SDUC hosts. Compatibility runs forward, not backward.

Compatibility isn’t about form factor, but the firmware and controllers that power both the card and the host device. This is why an SDXC card can slide into an older camera, but may be misread or not be recognized altogether. Some sources online may suggest reformatting an SDXC card to use FAT32 to force compatibility with an older device, but this can cause performance issues, including data loss5. Only attempt this solution if the manufacturer explicitly supports it.

To help ensure a card is compatible with your device, review your owner’s manual for supported card types and maximum capacities. If your device maxes out at 32GB, the answer is a high-quality SDHC™ card, not a reformatted SDXC™ card.

If your device is a camera, you can also refer to our memory card compatibility chart.

Speed Classes and Bus Interfaces: UHS-I, UHS-II, SD Express and V-Ratings

SD card capacity classes and speed classes have no impact on each other. An SDHC card can be faster than an SDXC card; buying a bigger card does not buy you a faster card, strictly. For example, the SANDISK Extreme SD UHS-I Card 512GB is an SDXC with a V30 speed class rating, which is slower and smaller than the SANDISK Extreme PRO SD UHS-II V90 Card - 128GB, an SDHC with a V90 speed class rating6.

SD cards typically list two speeds on their labels: the bus interface speed (its theoretical max write seed), and the speed class (its minimum sustained write speed). UHS-I, UHS-II, and SD Express denote a card’s bus interface speed, offering theoretical max write speeds of up to 104MB/s, 312MB/s, and 985MB/s respectively7 V30, V60, and V90, meanwhile, indicate a card’s speed class, guaranteeing minimum write speeds of 30MB/s, 60MB/s, and 90MB/s8.

When purchasing memory cards, it’s important to match the camera’s recording bitrate to the appropriate bus interface and speed classes. If you’re recording 4K, 10-bit footage, for example, you’ll be looking for a V60 SDXC card with a UHS-II bus interface.

Check out our guide to SD card speed classes for more details.

SDHC vs SDXC by Use Case: What to Buy for Your Gear

The vast array of capacities, speed classes, and bus interfaces can make selecting the right SD card for your use case tricky. Use the matrix below as a guide, and be sure to cross-reference with your device’s manual helps ensure compatibility and optimum performance9.

Use case Suggested Capacity class Suggested Speed class Suggested bus interface Reasoning
1080p video and everyday photography SDHC C10, U1 UHS-I Slower, lower capacity cards meet the demands and save you money.
DSLR and mirrorless cameras SDXC U3, V30, V60, V90 UHS-I, UHS-II High resolution and bitrate recording requires faster, higher capacity cards.
4K video SDXC U3, V30, or higher UHS-I, UHS-II Higher speed class or bus-interface as the device’s bitrate demands.
8K video & professional cinematographers SDXC V90 UHS-II Performant storage for demanding work.
Continuous RAW burst photography SDXC U3, V30, V60 UHS-I A faster card prevents your camera from buffering out and losing shots.
Drones and action cameras microSDXC V30 or higher UHS-I, UHS-II Consult the device manual for
Handheld gaming consoles microSDHC, microSDXC, microSD Express V30 or higher UHS-II, SD Express Newer consoles may require microSD express. Check the manufacturer’s suggested storage expansion for the most up-to-date information.
Smartphones microSDXC V60 or higher UHS-II Look for cards with an A1 or A2 application performance class.
Dash and security cameras microSDHC or microSDXC U3, V30 UHS-I For surveillance, endurance is the most important feature.

How to Choose the Right SANDISK™ Card for Your Workflow

To help ensure you buy the right SD card for your workflow, follow these four steps:

  1. Confirm host device compatibility — SDHC-only or SDXC-capable — from the manual or by using our camera compatibility chart.
  2. Pick the right capacity, not the highest number. 32GB is plenty for a point-and-shoot digital camera.
  3. Pick the right speed class for your use case. You can refer to this guide for more guidance.
  4. Confirm authenticity of the card by shopping at approved retailers or directly from Sandisk. Counterfeit cards can cause serious problems for your workflow, including data loss.

Sandisk offers its SANDISK Ultra line of SD cards for everyday users and one of its SANDISK Extreme and SANDISK Extreme PRO cards for content creators and creative professionals.

Frequently Asked Questions

SDHC and SDXC cards are two capacity standards for memory cards. SDHC cards range from 2GB to 32GB and use the FAT32 file system, while SDXC cards range from 32GB and 2TB and use the exFAT file system1. These standards apply to SD and microSD cards.

Disclosures

  1. Source: The SD Association
  2. Source: Darwin’s Data
  3. Source: The Camera Guide
  4. Source: Darwin’s Data
  5. Source: SANDISK
  6. Video Speed Class 30 (V30), sustained video capture rate of 30MB/s, and Video Speed Class 90 (V90), sustained video capture rate of 90MB/s, designate a performance option designed to support real-time video recording with UHS enabled host devices. See www.sdcard.org/consumers/speed.
  7. Source: SD Association
  8. Source: SD Association
  9. Source: Memory Blog
  10. Source: Lexar
  11. Source: The SD Association
  12. Source: The SD Association
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