Understanding the Differences Between SD, SDHC, and SDXC Cards and Their Class Ratings
When it comes to Secure Digital (SD) cards, microSD cards, SDHC cards, and SDXC cards, consumers often find themselves overwhelmed with choices. This article aims to demystify the differences between these card types and their class ratings, explaining how they impact performance and storage capacity.
SD Secure Digital Cards
SD Secure Digital (SD) cards are the oldest and most basic type of SD memory cards. They are limited to a storage capacity of up to 2GB and use the FAT12 and FAT16 file systems. These cards are suitable for users with modest storage needs but are becoming increasingly rare in the market due to advancements in storage technologies.
SDHC Secure Digital High Capacity Cards
SDHC Secure Digital (SDHC) cards provide a significant increase in storage capacity, ranging from 2GB to 32GB. They use the FAT32 file system, surpassing the limitations of the SD format. SDHC cards are ideal for users who require more storage space but don’t need extreme high-performance capabilities.
SDXC Secure Digital Extended Capacity Cards
SDXC Secure Digital (SDXC) cards offer even higher storage capacities, ranging from 32GB to 2TB. They use the exFAT file system, which is better suited for large-capacity storage needs. SDXC cards are recommended for users who demand high storage capacity and may include content creators, photographers, and videographers who require fast and reliable storage solutions.
Class Ratings Explained
The class ratings (Class 2, 4, 6, 10) indicate the minimum write speed of the card, which is crucial for tasks such as recording video or taking high-resolution photos. Here’s a detailed breakdown:
Class 2: Minimum write speed of 2 MB/s Class 4: Minimum write speed of 4 MB/s Class 6: Minimum write speed of 6 MB/s Class 10: Minimum write speed of 10 MB/sThese speed ratings are essential, especially for users who want to ensure smooth performance when recording high-definition video or handling large files. For example, Class 10 cards are highly recommended for 4K video recording, while Class 6 or 10 cards are suitable for SD video recording.
Combining Storage Capacity and Speed
It’s important to note that the type of SD card (SD, SDHC, SDXC) and its class rating are not always mutually exclusive. A higher capacity card like SDXC can also have a high-speed class rating such as Class 10, making it suitable for demanding applications. This combination offers both the necessary storage capacity and speed performance for professional users and content creators.
Additional Types of SD Cards
In addition to the commonly known SD, SDHC, and SDXC cards, there are other types:
SDUC (Secure Digital Ultimate Capacity): Cards that can store more than 2TB of data. They use the exFAT file system and offer extremely high storage capacities, up to 128TB, making them suitable for users who need the maximum amount of storage available. UHS (Ultra High Speed): This is a speed class for SD cards and SDHC/SDXC cards, not a storage capacity class. For example, UHS-I cards can achieve a maximum write speed of 104 MB/s, while UHS-II cards can achieve up to 312 MB/s. UHS cards are designed for extremely high-speed data transfer and are often used in professional videography and photography.Conclusion
In summary, the types of SD cards (SD, SDHC, SDXC) mainly relate to their storage capacities and formats, while the class ratings indicate their speed performance. By understanding these differences, consumers can make informed decisions based on their specific needs, whether it be for general use, consumer electronics, or professional applications.