The ULTIMATE Guide to Photography SD Card Speed & Storage
Trying to figure out how fast an SD card transfers information can be tricky because the face of an SD card is generally littered with symbols and numbers. Every single one of these symbols and numbers gives you information about the SD card but, to the average consumer, they mean nothing.
To find the speed rating of an SD card, you must first determine its speed class. The next step is to find the minimum sequential write speed associated with the SD card’s speed class. Finally, ensure the operating mode matches the speed class.
This article gives you easy reference resources to help you understand and select the best SD card for your camera.
What Is an SD Card Used for in Photography?

In photography, SD cards are used to store and transfer images from cameras to external devices such as computers. SD cards come in three form factors; full size, mini SD, and micro SD. Digital cameras used for photography utilize full-size SD cards.
Some cameras utilize other storage mediums like CFexpress but, in general, most photography cameras use SD cards. SD cards come in a variety of storage capacities and speed ratings. The storage capacity of an SD card (generally measured in gigabytes, GB) determines the amount of photos you can store on it.
The speed rating of an SD card determines how fast your SD card can take incoming data sent from your camera. Speed ratings are crucial for high-resolution and burst photos, as a higher speed rating reduces buffering time.
For more information about the files that SD cards store for photographers check out my article explaining what RAW photos are.
How Do SD Card Speed Ratings Work?

You may have taken one look at an SD card and assumed the number on the front, something like “300MB/sec” is the speed rating of an SD card. I don’t blame you for thinking that, though it’s not completely true. Before we can understand how to read speed ratings, first we need to understand where they come from.
SD standards are outlined by the SD Association. Speed ratings are measured in terms of video performance as this is the most intensive task for SD cards. After all, SD cards weren’t built to be used as random access memory for things like boot drives. SD cards are built for removable and portable storage and, in the photography world, are used as a temporary means to get information from a camera to a computer.
To avoid frame drops when recording video, SD cards need a fast enough minimum write speed. Write speed refers to how fast data is transferred from your camera to your SD card. Minimum write speed is not only a concern on the SD card but also the camera. For example, the minimum write speed needed for your camera to record 4k 10-bit video will be higher than 1080p 8-bit video.
In general, the numerical speed value on the face of an SD card refers to the read speed of the card, not the write speed. The read speed of an SD card is how fast you can access the data already stored on the SD card while the write speed refers to how fast you can transfer information to the card.
In some cases, you’ll have two-speed values listed on the face of your SD card followed by an “R” and a “W” for “Read” and “Write” so it would look something like this: “300MB/s R”.
In this section, I’m going to guide you through the steps to figure out exactly how fast an SD card can write.
SD Types
The first thing you need to do when determining your SD card’s speed rating is to look at what type of SD card it is. When looking at an SD card, you’ll notice it has one of four labels; SD, SDHC, SDXC, and SDUC. You may have an SD Express card, but that is a separate topic that I will discuss later.
Your SD card type is needed to help you determine speed classes that we will learn about later. Each SD type also is only able to have a certain range of storage capacity. Check out the chart below to find out what SD type you have based on its logo.
SD Type | SD Logo | Capacity |
---|---|---|
SD | ![]() | Up to 2GB |
SDHC | ![]() | More than 2GB up to 32GB |
SDXC | ![]() | More than 32GB up to 2TB |
SDUC | ![]() | More than 2TB up to 128TB |
Speed Classes
The SD Association defines four established speed classes for SD cards; Speed Class, UHS Speed Class, Video Speed Class, and SD Express Speed Class (source). These four speed classes have different ratings that indicate their minimum sequential write speed.
Minimum sequential write speed is the minimum speed an SD card can write (save) data in a continuous, sequential manner. Continuous means there are no interruptions to the data transfer from when it begins to when it is completely transferred. Sequential means it transfers data using a first-in-first-out system; the card transfers data in the order it receives it.
To understand this concept, let’s imagine a pay-to-use parking lot. Let’s pretend this lot has a parking attendant, Jim; no, not a machine or app, an actual human being managing parking. There’s a lineup of cars coming from the road to park in the lot, Jim the attendant needs to process each car’s payment and direct them to a specific parking stall.
This process takes time, we can think of the speed the attendant processes the cars as an SD card’s minimum sequential write speed. So, if a card’s minimum sequential write speed is 20MB/sec, it’s like saying the slowest speed that Jim the parking lot attendant can process and park cars is at a rate of 20 cars per second (Jim is really good at his job). Jim may be able to process more, like 100 cars per second or even 300 cars per second, but he won’t process any less than 20 cars per second.
In this analogy, the road and cars are coming from are comparable to your camera that is sending information to the SD card. Even if there are 1,000 cars piled up waiting to park, they all need to wait to be processed by Jim the attendant and are therefore limited to his speed. In that same way, your camera can only send information out as fast as your SD card can receive it.
The parking lot represents the SD card’s storage capacity. Remember, Jim isn’t just letting these cars into the lot, he’s directing them to a specific parking stall. When your camera sends information to your SD card, it’s not randomly shoved into the card’s storage. Instead, the information is organized based on when it was added to the card, sequentially.
Finally, Jim the parking lot attendant represents the card’s minimum sequential write speed. It doesn’t matter how many empty spots there are in the parking lot, the speed at which they are processed and parked is completely reliant on Jim. It doesn’t matter how fast your camera can send information out if your SD card can’t write it fast enough to keep up.
Minimum sequential write speed is a standard set by the SD Association. On the other hand, maximum write speed (usually listed in product descriptions) is based on internal testing by the manufacturer of each specific SD card. This is why we can see two cards of the same speed classes with different speed ratings. I recommend using the SD Association standards as reference when buying an SD card instead of the manufacturer’s internally determined maximum write speed.
When you go to buy an SD card, you’re going to see a bunch of icons printed on the front. These icons give you information as to the SD card’s capabilities. Below, I’ve included a table that you can use as a reference when buying an SD card; it tells you what speed class an icon belongs to and the corresponding minimum sequential write speed.
Minimum Sequential Write Speed | Speed Class | UHS Speed Class | Video Speed Class | SD Express Speed Class |
---|---|---|---|---|
600MB/sec | ![]() E600 | |||
450MB/sec | ![]() E450 | |||
300MB/sec | ![]() E300 | |||
150MB/sec | ![]() E150 | |||
90MB/sec | ![]() V90 | |||
60MB/sec | ![]() V60 | |||
30MB/sec | ![]() U3 | ![]() V30 | ||
10MB/sec | ![]() C10 | ![]() U1 | ![]() V10 | |
6MB/sec | ![]() C6 | ![]() V6 | ||
4MB/sec | ![]() C4 | |||
2MB/sec | ![]() C2 |
Matching Speed Classes to Operating Modes
You may have seen the terms “UHS-I” or “UHS-II” on SD cards or product pages. This refers to the operating mode of the SD card. Each operating mode can handle a specific group of speed classes meaning varying minimum sequential write speeds between two cards both utilizing the same operating mode.
It’s for this reason that SD cards post both speed classes and operating modes on their front faces. If you have a mismatch between operating mode and speed class on your SD card, it’s a serious red flag. For instance, if you have a card that is indicated to be UHS-I but also marked as V90, it’s highly likely to be an imitation or fake. Below is a reference table to help you match speed classes to operating modes.
Operating Mode | Speed Classes |
---|---|
NS Mode | C2, C4, C6 |
HS Mode | C2, C4, C6, C10, V6, V10 |
UHS-I Mode | C2, C4, C6, C10U1, U3V6, V10, V30 |
UHS-II & UHS-III Modes | C4, C6, C10U1, U3V6, V10, V30, V60, V90 |
SD Express Mode | E150, E300, E450, E600 |
A quick note about SD Express is that SD cards with this operating mode utilize PCIe and NVMe interfaces and a UHS-I interface. What this means practically is that SD Express cards are not compatible with UHS-II interfaces but are compatible with UHS-I interfaces (source). This becomes important when you go to find an SD card that works with your camera’s SD ports and when you go to connect your SD card to a computer.
As you can see, just because something is UHS-II doesn’t necessarily mean it will reach the speed of V90. This is why you can’t rely on operating mode as a signal of SD card speed. You can have a UHS-II card running at V10 and a UHS-I card running at V30. What’s important is to look for the speed class on your SD card. The reason operating modes are useful to you as a consumer is to help you ensure they match your marked speed class and they work with your SD ports whether that be a camera or computer.
Does SD Card Speed Matter for Photography?

SD card speed does matter for photography; A faster SD card speed allows photographers to shoot faster and longer bursts. It also allows photographers to shoot bursts with higher-resolution photos.
If your SD card is too slow, there will be a buffer (wait time) after taking photos before you can take more. This buffer is the time it takes your camera to transfer the photos from its internal temporary storage to your SD card.
There are two key factors you need to consider when it comes to SD card speeds in photography; file size and burst shooting. You never want to miss a crucial candid moment or action shot because your card is buffering. So, yes, SD card speed is quite important in photography. With this in mind, let’s discuss how fast an SD card should be.
How Fast Should an SD Card Be?

There are two common mistakes that photographers make when it comes to SD card speed; they either completely ignore it or they just buy the fastest cards they can find. Though it’s not technically a bad thing to buy the fastest SD card available, it does mean you could be wasting money.
The speed at which data is transferred from your camera to your SD card depends on two things; how fast your camera can send information out and how fast your SD card can take information in. If your camera’s SD card slot(s) are UHS-I compliant, we’ll say they can transfer information at an average of 104MB/sec (source). Now, the trick is to find an SD card that transfers at least that speed.
Here’s the thing, you can buy a card with SD Express technology that can write data at 500MB/sec but that means nothing in terms of camera performance because, in this case, your performance is being held back by your camera’s data transfer speeds. You don’t need 500MB/sec write speeds, and you’re going to pay more money for it in this scenario. The only benefit this card would have for you as a photographer is faster read speeds when connecting it to a computer.
The key to finding the right SD card in terms of speed is to first research what speed your camera’s SD card slot(s) can transfer information. To do this, search for your camera model’s product page on its manufacturer’s website. Let’s look at the Fujifilm X-T5 as an example.
On one of the official Fujifilm websites, we can see the specification sheet for the X-T5. Under “Memory Card Slot”, we see that the X-T5 has “Two SD memory card slots (UHS-II compliant)”. If we reference the chart above, we can see that UHS-II compliant means a speed class of up to V90. What this tells us is that the Fujifilm X-T5 cannot transfer data fast enough to match SD Express class cards.
When we are buying an SD card for the Fujifilm X-T5, the fastest card we should buy is one marked V90. Do we need a video speed class of V90? Not necessarily. You as a photographer need to decide if this SD card will be used for long burst shooting, bursting shooting with high resolution, or for video. If not, then consider saving some money and buying an SD card with a video speed class rating of around V30 or V60.
Want to learn more about the technical side of photography? Check out my article detailing what noise is in photography.
How Much Storage Should an SD Card Have for Photography?

The amount of storage that you need as a photographer is reliant on your shooting environment and shooting style. Moreover, the resolution of your sensor affects the amount of information it captures, also affecting the amount of storage you need. For example, an 18MP camera’s images will be a smaller file size than a 45MP camera’s images.
In general, professional photographers use a minimum of 64GB SD cards. It is common for professionals to use 128GB or 256GB SD cards in cameras with dual card slots. Photographers also bring backup SD cards to their shoots as a precautionary measure.
As a photographer, you need to consider what exactly you are photographing. Are you shooting a long event? You’ll need more storage. A quick shoot? You probably won’t need as much storage. Lots of action? Burst shooting requires more storage.
Also, consider the potential use of dual card slots. Cameras with two SD card slots can hold two SD cards worth of storage. You can also use dual SD card slots to store the same photos on both SD cards so you have a backup in case one card fails.
It’s always a good idea to have more storage than you need. It’s a photographer’s worst nightmare to run out of storage mid-shoot. The last thing you want is to have to go through your gallery and delete photos to clear space mid-shoot.
If you are shooting photos and videos, you’ll need significantly more storage. For photography, I recommend at least 64GB of storage. You can get by with 32GB in a pinch, but 64GB gives you some breathing room if your shoot runs long or you forget to back up old shots from your SD card.
Cheap Versus Expensive SD Cards

When it comes to SD cards, the whole “cheap versus expensive” debate is really a comparison between reputable and no-name (or imitation) brands. With reputable brands, lower-cost SD cards will give you lower performance or lower storage capacity. Reputable brands will always cost more than no-name brands.
Though the $0.50 1TB SD card off AliExpress may look tempting, I can guarantee you’ll regret buying it. Reputable brands often have solid warranties for their SD cards. Some of the most reputable companies also include file-recovery software with their SD cards. One example of this is SanDisk’s RescuePRO Deluxe software which is included with some of their SD cards.
Reputable SD card brands are also registered with the SD Association to ensure quality standards are met. Along with this, reputable companies have better customer support channels, which is likely non-existent with no-name or imitation brands.
What SD Card Is Best for Photography?

Now that we’ve covered how to interpret SD card speed ratings, how to match SD card speed to your camera’s output, and the difference between reputable and no-name brand SD cards, let’s look at some of the most reputable brands when it comes to SD cards. I have attached an Amazon to the photos of each of these SD cards and made sure they are as comparable to each other as possible. Always remember to find the best speed rating within each SD lineup to work with your camera as outlined earlier in this article.
SanDisk Extreme PRO
SanDisk is one of the top brands when it comes to SD Cards and for good reason. They have a wide range of reliable SD cards with different speed ratings and storage capacities. The specific SD card linked above is SDXC UHS-II with a video speed class of V60 and a UHS speed class of U3. This means its minimum sequential write speed is 30MB/sec and 60MB/sec for video. The maximum write speed SanDisk has rated this SD card at is 100MB/sec. One special feature of SanDisk Extreme PRO cards is that they usually come with SanDisk RescuePRO Deluxe file recovery software.
Lexar Professional Silver PRO
Lexar is another well-known company in the SD card market. Lexar is reportedly somewhat reliable but not quite on par with SanDisk cards according to users on Reddit’s wedding photographer forum (source). One benefit to Lexar cards is that you will generally get faster maximum write speeds and slightly more storage for a lower cost when compared to SanDisk cards. The card linked above is also an SDXC UHS-II card with a video class of V60 and a UHS speed class of U3. Like its rival SanDisk card, this means its minimum sequential write speed is 30MB/sec and 60MB/sec for video while the maximum write speed reported by Lexar is 120MB/sec.
Kingston SDXC Canvas React Plus
Kingston is a reputable brand that makes both consumer and pro-grade storage solutions including SD cards. In the photography world, Kingston has mostly solid reviews (source, source). The specific card linked above is SDXC UHS-II with a video class of V90 (they don’t have a card that is V60) and a UHS speed class of U3. This means that this Kingston card has a minimum sequential write speed of 30MB/sec and 90MB/sec for video while the maximum write speed reported by Kingston is 260MB/sec. This specific card also comes with the MobileLite Plus UHS-II SD Reader which can transfer data at a speed of up to 300MB/sec.
Sony Memory Card UHS-II SD
Sony is a massive company that is known globally across multiple industries. In the photography world, Sony’s SD cards are seen as a solid, reliable choice (source). The specific card linked above is SDXC UHS-II with a video class of V60 and a UHS speed class of U3. This is comparable to the SanDisk and Lexar cards linked above as the minimum sequential write speed of this card is 30MB/sec and 60MB/sec for video. Sony has reported the maximum write speed of this card to be up to 100MB/sec.
Jeremy Goh
Jeremy grew up volunteering at church and has also worked in a church setting. Along with working as a freelance creative, Jeremy is studying for a business degree in finance and international business.

