How Do I Choose the Best SD Card for My Camera?

Dear Lifehacker,
Confused About SD

Title image by Brett Yoncak.

How Do I Choose the Best SD Card for My Camera?


Dear Confused About SD,
Congratulations on the new camera! Your problem is actually quite common-many people buy a new camera, try to use the SD card from the camera they've had for several years, and find out that photos work but video won't, for example, or they have some other strange quirk. The reason for that ties into the answer to your second question: how you can make sure to buy the best SD card when you choose to upgrade. Let's tackle them one at a time. Photo by Ryosuke Sekido.

Older SD Cards and New Cameras

The issue you may be having with your old SD card is that it may be too slow for your new camera to write effectively to it. Normally this is a problem that people encounter in the inverse-trying to use a newer SD card in an old camera-but the issue can go both ways. Usually this happens when you're trying to record video to your SD card on a new camera, especially in HD. The older card simply can't write data fast enough to keep up with what's coming in from your camera, and the video becomes choppy or the recording just won't work. In the case of newer SD cards and older cameras, the card should work, it just won't perform up to its maximum speed.

To understand why this happens, you have to understand SD card classes and their respective speeds. It's a fairly arcane topic, but it's one that's important to digital camera and camcorder owners that's often poorly explained by SD card manufacturers and camera makers.

SD Card Classes, Speeds, and Storage

The first and most basic suggestion when buying a new camera or camcorder is to check the documentation (preferably online before you make the purchase) to see what the recommended SD card type and speed for the device is. Then you'll have a concrete recommendation as to what you should buy. If you can find it in the owners manual, follow that. Unfortunately, many camera and camcorder manufacturers either bury this information or phrase it in terms of the suggested card "class" and "x rating," two terms that are never well explained in the manual. Here's what they mean:

How Do I Choose the Best SD Card for My Camera?

Class: SD cards come in four classes: Class 2, class 4, class 6, and class 10. Each class rating corresponds with its minimum write speed. That means that a Class 2 SD card can write data at least at 2MB/s, a Class 4 at 4MB/s, and so on. Keep in mind that these are minimum write speeds, and even though most card manufacturers put this number up front on the packaging of the card, the minimum write speed usually isn't the value that's problematic when you're mixing new devices and old cards. Photo by Cristiano Betta.

It is, however, an issue when you mix new cards and old devices: if the old device simply can't write as fast as the minimum sustained write speed as indicated by the SD card's class, you're going to have problems saving data to the card.

X Rating: While an SD card's Class corresponds with its minimum write speed, its x rating corresponds with its maximum rated write speed. This is where a number of people who are using older cards and newer devices: if your old SD card is, for example, a 13x card (which can write data at a maximum write speed of 16 Mbit/s) in a device that requires at least a 40x card (maximum write speed of 48Mbit/s,) the card won't be able to keep up with the device. There's an excellent table highlighting the different x ratings and how they correspond to card classes here at Wikipedia.

If this is still confusing, don't worry. Most SD card buyers won't need to worry about x rating: it's often used as a marketing number on an SD card's package to show how fast the card can operate. At the same time, camera manufacturers usually include it because they want users to know the minimum x rating a card should have before it can be used with that device. In reality, if you go shopping with that number, you'll buy a card that will match up with your device well, and if you're using an SLR or plan to shoot a lot of video, you may want to spend some more money and buy a card with a higher x rating and SD class rating than your camera's minimum requirements.

How Do I Choose the Best SD Card for My Camera?

Storage: The size of the SD card is likely the deciding factor for most people. If you're using your SD card in a point-and-shoot, you only take occasional photos, and you're taking those photos at JPEG images, a small SD 4-8GB SD card will allow you to store thousands of images. If you're shooting in RAW with a point and shoot and you're the same type of photographer, you may want to upgrade to a 16GB card, but you'll still be able to keep at least a few thousand on an 8GB card. There's no reason to break the bank on a 32GB card if you carry a point-and-shoot and don't take video. Photo by Jasleen Kaur.

At the same time, if you do take video, or you use a DSLR capable of taking higher-resolution photos than a smaller point-and-shoot, now you have to consider how long your videos are and how much space on the card they'll take. If you shoot video at all and take pictures in RAW, you'll probably want at least a 16GB card, likely 32GB to make sure you never run out of room on your camera. This table from the SD Association is helpful in determining how much you'll be able to store on your camera based on the type of media you plan to put on it.

The Final Word

We touched on some SD and flash card suggestions back when Adam Dachis took us to night school to learn the basics of photography. Not much has changed since then: you'll likely best be served by a Class 6 card in your new-ish device, and buy the amount of storage that's best for your use case and within your budget.

There's no harm in overbuying, but buying a 32GB Class 10 card when you carry a point-and-shoot, take pictures as JPEG, and never take video is probably a waste of space and money. If you have an old, class 2 SD card and you want to try it in your brand new DSLR, make sure you back up whatever's on it first and keep in mind that you'll likely have issues writing photos to it as quickly as your camera can take them, or saving video as quickly as your camera can record it.

While you should definitely review your owner's manual for the best type of SD card to use with your device, if your manual isn't clear on the matter or doesn't tell you, you'll likely be best served by buying a Class 6 card with the storage you need for your use case.

We hope that helps, and happy shooting!


Do you have any additional advice for Confused? Any tips to help him understand the intricicies of SD cards and buying the right one for his camera? Share your tips and suggestions in the comments below.