The Differences Between SD and SDXC Cards

In this day and age, we are able to do just about anything through the advancements of technology. In any device that you use, storage is going to be a crucial aspect. While most devices have internal storage, having external storage becomes a must.

You have no doubt heard of SD cards before. These little storage cards make it easier to gain additional storage and transfer files from device to device. But there are different types that can make understanding them confusing, like SDXC cards.

What is an SD/SDXC Card?

Before we start worrying about the differences between SD and SDXC cards, it helps to know what they are in the first place. When you check out reviews of either type of card, you will find that they are simply storage devices. They run the gamut from 2GB of additional storage all the way up to 1TB.

Storage sizes can vary depending on the kind of card you choose. The SDXC cards are the most robust, topping out at 1TB of extra space. They also tend to be the larger of the two, so just be aware of that before you run out get an SDXC card for your device.


Now that we know the basics, it is time to look at what separates these two storage devices. The storage capacity is usually designated by the type of card. SD (Secure Digital) is the oldest of the bunch. It is also the most limited, maxing out at 2GB of storage.

SDXC are extended capacity cards. They are bigger even than SDHC (High Capacity), which can store up to 32GB. With SDXC, you can store up to 2TB in some instances on a single card. That said, some older devices might not support SDXC, so check before just running out and buying one.

Speed Class

One of the specifications you find will be speed class. You will find a “C” somewhere on the memory card to represent what the minimum write speed is. This is important when you are using video or large images in succession.

These are divided into four classes – 2, 4, 6, and 10. The number represents the minimum speed per second that is sustained. Obviously, the higher the number, the higher the minimum speed.

Rate Speed

Things can get a touch confusing when it comes to rate speed. There are a variety of things that could be referring to the speed of the card. You will find either MB/s (megabytes per second) or a big number with an “X” behind it. Sometimes, it’s both.

The “X” is basically a marketing term. A 1x represents 150KB/s, so 600x is basically 90MB/s. It’s a way to make it seem far faster than it actually is. The read speed is typically represented, and it is usually higher than the write speed.

Video Speed Class

For those trying to shoot video, particularly in higher resolutions like 4K or 8K, then you need to find a class of SD card that will meet the occasion. You will find a “V” and a range from 6-90 on each card. The higher the number, the more sustained write speed you have. For video, going with something higher is a must.

Overkill or Future Proofing?

For older equipment that is going to be upgraded soon, a faster card could make sense. If you don’t need the performance, it’s just a waste of money. Take the time to go over your equipment and the benefits that each SD card offers. You can then find something that best meets your needs and budget.