Buyer’s Guide: How to Find the Right Memory Cards

Which Camera Memory Card

Which memory cards are right for your camera and your application and what do all the abbreviations mean? Our buyer’s guide with purchase advice provides the answers.

Purchase advice for memory cards

If you are looking at the datasheets of current cameras, you will find some very impressive technical specifications. For example, both SLR and mirrorless system cameras often come with high burst rates, and most cameras now record high-resolution video in 4K.

Basically, this is a great thing when a camera can boast high speeds and impressive specifications. But sometimes the capabilities of a camera cannot be fully exploited if you do not have the right memory card. 4K videos, for example, generate large amounts of data that must be written to the memory card quickly. That means you need a very fast storage medium.

But which memory card is the right one for your own camera? How much money do you really have to spend and what do all the abbreviations mean? In this article, we want to explain everything you need to know about memory cards. In addition, we want to answer the most frequently asked questions and make some concrete purchase recommendations. Our memory card purchase advice is written especially for photographers, but the explanations are of course universally valid.

The different types of memory cards

There are several types of memory cards. This is often recognizable at first glance because the different types of memory cards are different in size. In the context of cameras, you will mostly find the following types:

  • SD, SDHC and SDXC (24.0 x 32.0 x 2.1 mm)
  • miniSD (20.0 × 21.5 × 1.4 mm)
  • microSD (11.0 × 15.0 × 1.0 mm)
  • CompactFlash or CFast (42.8 × 36.4 × 3.3 mm)
  • XQD (38.5 × 29.8 × 3.8 mm)

First and foremost, one should determine which type of memory card is required for one’s own camera. Of course, a microSD card does not fit in an XQD slot, an SD card does not fit into a CF slot, and so on. Which type of memory card your camera supports is usually stated in the enclosed manual with the technical data. Alternatively, just have a look at the website of the manufacturer and there listing of the specifications of the camera. There you will find the information stating which memory card is needed for your own camera.

The vast majority of SLR cameras or system cameras work with SD memory cards. The SD card is therefore the memory card that is the right choice for almost all photographers. CompactFlash, CFast and XQD memory cards are only supported by some really expensive cameras, while miniSD and microSD cards are mainly used in small electronic devices such as smartphones. Since the miniSD cards are now largely extinct, they are listed here only for the sake of completeness.

SD Memory Cards

The SD memory card is therefore the most important storage medium for all photographers – and if you look a bit more closely at the SD cards, you will find that there are many differences between the cards. SD, SDHC, SDXC, U1, U3, Class 6, Class 10, USH-I, UHS-II – there are countless shortcuts that often cause confusion at first. As such, we will address the jungle of terms in turn and explain the various details.

Incidentally, most of these specifications also apply to microSD cards, as these are part of the family of SD memory cards.

What is the difference between SD, SDHC and SDXC?

The difference between SD, SDHC and SDXC memory cards is quickly explained. The various names refer only to the capacity of the memory cards. When the first SD memory card was introduced in 2001, it had a maximum size of 4 GB. Of course, that was not enough after a few years, so you needed a memory card with a higher capacity – the SDHC memory card, which can accommodate a maximum of 32 GB. HC stands for “high capacity” in this case. And some time later followed the SDXC memory card, which has space for 64 GB up to theoretically 2 TB.

  • SD memory card: Capacity of 4 GB
  • SDHC memory card: Capacity between 4 GB and 32 GB
  • SDXC memory card: Capacity between 64 GB and 2 TB

Do not confuse writing and reading speed

Generally, memory cards have two different speeds. On the one hand there is the writing speed, which indicates how quickly data can be written from the camera to the memory card. On the other hand, there is the read speed, which determines how fast the contents of the memory card can be read by another medium (usually the computer).

For photographers, the speed of writing is the more important of the two speeds, because 4K videos, for example, require a relatively high write speed. A high reading speed only has the advantage that the memory card can be read faster by the computer and the data can be transmitted more quickly.

As a rule, the reading speed of a memory card is higher than the writing speed. Most manufacturers therefore consciously print the faster reading speed on the packaging to attract customers – but in reality, writing speed is much more important. This is, as I said, in most cases slower and is therefore hidden somewhere on the back of the package. Many manufacturers often provide no write speed.

What does Class 6 or Class 10 mean?

With most SD memory cards, one finds a so-called Class indication. This ensures a constant minimum writing speed. In general, the read and write speeds of memory cards can vary within a certain range, as it is not always at the same speed. The class specification determines which minimum is always guaranteed when writing:

  • Class 2: at least 2 MB/s
  • Class 4: at least 4 MB/s
  • Class 6: at least 6 MB/s
  • Class 10: at least 10 MB/s

For example, if you want to record videos in Full HD, you need at least a Class 6 memory card. If you were to insert a Class 4 memory card and the writing speed dropped to the minimum of 4 MB/s, the video data could not be written to the memory card because it is too slow. As a result, the video recording would be terminated.

All newer memory cards are Class 10 memory cards. The class specification is usually identified by a circled number on the memory card. In general, this information can be a bit outdated, because there is always new information available, or the standard changes.

What are UHS memory cards?

When the SDXC memory cards with a larger capacity were introduced in 2009, the SD Association had also introduced the so-called UHS memory cards. It was clear that sooner or later one would not only need more storage space but also higher transfer speeds.

UHS cards use a faster data bus, which enables faster read and write speeds. A distinction is made between UHS-I memory cards and UHS-II memory cards. These can in theory reach the following maximum transmission speeds:

  • UHS-I: maximum of 104 MB/s
  • UHS-II: maximum of 312 MB/s

One should note that these are the maximum transmission speeds! Not like the class figures around the minimum speeds. In addition, not all memory cards exactly reach these maximum speeds. These are only the maximum speeds theoretically possible from a technical point of view using UHS technology. The speeds of different memory cards vary depending on the price range and are therefore usually specified by the manufacturers of the respective memory cards.

In order for the enormous speeds of a UHS memory card to be fully exploited, the camera must also support UHS-I or UHS-II. If they do not, UHS memory cards can still be used in the camera anyway, but they are just a bit slower because the UHS technology is not supported by the camera.

In other words, if your camera is not compatible with UHS memory cards, it makes no sense to invest a lot of money in an expensive UHS-II memory card that would ultimately only perform as fast as a normal SD memory card.

Almost all of the newest camera models support UHS-I memory cards, so these cards are currently very common and also very cheap. UHS-II, however, is only supported by a few cameras.

What does U1 or U3 mean?

If you have a UHS-I or UHS-II memory card, then thanks to the information provided by the manufacturer on the packaging, you know what maximum  speeds are possible. In addition, of course, there is still an indication of the minimum write speeds.

For normal SD memory cards, this was already explained above in the class specification section. For UHS memory cards, called the whole “UHS Speed Class Specification,” this is basically the same, but just has a different name. The UHS Speed Class is usually abbreviated as U1 or U3. U1 corresponds to Class 10. That means:

  • U1: writes at least 10 MB/s
  • U3: writes at least 30 MB/s

The U1 or U3 specification thus effectively replaces the old class specification. Why are most of the memory cards still specifying both values? Quite simply, if you use the UHS memory card in a camera that does not support UHS, then the old class statement is used.

What does the specification 633x or 1000x mean?

Some manufacturers specify the reading or transmission speed as a factor of the simple CD reading speed. This is 150 kilobytes per second. For example, the indication “633x” on a memory card means that the reading speed is 633 x 0.15 megabytes per second (that is, 95 MB/s).

What is the difference between UHS-I and UHS-1?

Sometimes one finds the indication UHS-I (with a Roman numeral one) and sometimes the indication is UHS-1 (with an Arabic numeral one). The indication with the Arabic one is a composition of “UHS” and “U1.” A UHS-3 memory card would accordingly be a UHS memory card with the UHS speed class indication U3. Therefore, it can write a constant 30 MB/s and it’s not (as you might think) the successor to UHS-I and UHS-II. A UHS-I (Roman one) merely indicates that theoretically a maximum speed of 104 MB/s can be achieved.

Summary and example of what was discussed in the overview

Now that we’ve explained the various types of memory cards, let’s summarize using an example:

SDXC memory card

  1. This is an SDXC memory card.
  2. The Roman “I” stands for UHS-I. For a UHS-II memory card, there would be an “II”.
  3. It is a Class 10 memory card (= minimum write speed of 10 MB/s when using the card in a camera that does not support UHS).
  4. It is a U3 memory card (= minimum write speed of 30 MB/s if the camera supports UHS).
  5. The card has a capacity of 64 GB.
  6. Maximum speed: 90 MB/ Attention! This is usually the maximum reading speed, but more important for photographers is the writing speed, which is usually much lower (which is why the manufacturers do not print them in large text on the memory card).

How to find the right SD memory card?

So now that we’ve explained all the important terms and abbreviations around memory cards, let’s get to the “practical” aspect of memory cards and some buying advice! When should one buy a particular type of memory card? To answer that, we must first address some questions before you buy. Afterwards, we will make some concrete purchase recommendations.

Does my camera support SD, SDHC and SDXC?

First of all, you should check to determine if your camera supports SD, SDHC and/or SDXC memory cards. For all reasonably new cameras, this should be the case. However, some older models may not yet support SDXC. In this case, you would have to resort to an SDHC memory card.

Does my camera support UHS-I or UHS-II?

Second, check to see whether your camera is compatible with UHS-I or perhaps even UHS-II memory cards. UHS-II is currently only supported by a few cameras (as of the end of 2016), while UHS-I is very widespread, as already mentioned. If your camera is not compatible with UHS memory cards, you can theoretically resort to a very “normal” memory card – even though these are hardly available anymore. A UHS-I memory card should work in your camera as well. UHS memory cards can be purchased for less than 10 USD.

Do I want to be able to record videos in 4K?

4K videos generate enormous amounts of data, so you need a memory card with a relatively high minimum write speed. If the camera can record videos in 4K, it also supports UHS memory cards. It then becomes a question of whether you need a U1 or a U3 memory card?

To record 4K videos, you will always need a U3 memory card. Even with Full HD videos with high data rates (100 MB/s or more) you should use a U3 card. This really ensures that no errors occur during the recording. If you rarely work with videos and then only shoot simple Full HD videos, you can safely utilize a normal U1 memory card.

What is more important — minimum speed or maximum speed?

Suppose you have the choice between the following two memory cards, which are both equally expensive:

  • Card #1: UHS-I U1 (= minimum write speed of 10 MB/s) with a maximum write speed of 90 MB/s
  • Card #2: UHS-I U3 (= minimum write speed of 30 MB/s) with a maximum write speed of 60 MB/s

Which do you choose?

Card #1 can drop to a fairly slow 10 MB/s write speed, but it’s faster in terms of maximum speed. Card #2 has a better “base” with at least 30 MB/s but is slower at the top end.

The following rule applies here: If you do not want to record 4K videos and focus on the maximum continuous shooting speed of photos, you should use card number one. It’s not that bad when the speed of the memory card slows down a bit and usually you keep the shutter button depressed for just a few seconds anyway. For videographers, however, a stable base is clearly more important, especially if you want to film in 4K. Here, card number two would be the better choice because you are guaranteed a constant 30 MB/s are delivered.

If you do not want to make any compromises, just add a few dollars and buy a card #3, which has at least 30 MB/s and a maximum of 90 MB/s 🙂

Final tips

To put it together, here are three small tips that may help you decide which card is right for you:

  • If you buy a very simple SD memory card (not UHS), always buy at least a Class 10 memory card. There are basically no more price differences between Class 10 and Class 6, but with Class 10 you are always better positioned.
  • In terms of storage, we would always recommend at least 16 GB. Memory cards with a capacity of 8 GB fill quickly, even if you might want to shoot in RAW. There are also almost no price differences, as 16 GB memory cards can already be purchased for less than 10 dollar
  • Memory cards have a limited lifespan and can eventually break. For this reason, it is often useful to maintain two smaller or medium-sized memory card and not one large capacity card. Only those who want to record long 4K videos should have a very large memory card.

Specific purchase recommendations for SD memory cards

There are many good memory cards on the market, and in some cases, the different models do not really differ from each other. Sometimes it makes no difference whether one accesses memory card A or memory card B. With the memory cards which we recommend here, you can’t go wrong. We decided to recommend only memory cards from SanDisk and Transcend. This is simply because we have the best experience with these two manufacturers. Moreover, these are the two big names when it comes to storage media and both manufacturers have been delivering excellent quality for many years. Lexar is recommended as a manufacturer, but you should refrain from various cheap products.

The links in our product boxes lead you directly to Amazon, where the memory cards can be purchased at a reasonable price. Most memory cards are available in different sizes, so if you do not want to buy the version with 64 GB, but instead want the 32 GB, you can choose directly from Amazon on the respective product page. In addition, you usually have the choice between the standard packaging and the frustration-free packaging. This frustration-free packaging uses as few packaging materials as possible for shipping, which help protect the environment.

For money savers (16 or 32 GB)

If you only use a simple camera with a comparatively slow burst speed and want to spend as little money as possible on a memory card, you can use this UHS-I memory card. The price is well below 10 USD, and could not be cheaper:

If you need a bit more memory, but still want to spend as little money as possible, you can purchase this 32 GB memory card from SanDisk. The read speed is pleasantly fast with up to 80 MB/s, but the write speed is considerably lower. Unfortunately, SanDisk does not give an official value here. According to various tests, the average write speed is just under 20 MB/s.

Memory cards with 64 or 128 GB (different speeds)

The 64 GB size is perfect in the eyes of many customers. There are plenty of RAWs and videos here, but at the same time, you do not have to dig deep into your pocket. We’d like to recommend three different 64 GB memory cards: slow, fast, and extremely fast. These three memory cards are also available with 128 GB. So, if you need even more memory than 64 GB, you can choose the 128 GB version.

Rather slow and cheap

If you do not need too high of writing speeds, you can use this first memory card. It is the larger version of SanDisk’s already recommended “Ultra Memory Card.” Unfortunately, SanDisk does not give write speed here either, but according to tests, it should average about 20 MB/s. However, these values can fluctuate, sometimes even up to 40 MB/s. In any case, you get a lot of space for a really low price:

Fast, and thanks to U3, suitable for 4K

For about 30 USD you get a U3 memory card with 64 GB – a memory card that is suitable for 4K recordings! In addition, Transcend delivers a maximum write speed that is a whopping 60 MB/s. This is slightly superior to the counterpart of SanDisk (the SanDisk “Extreme”), where a maximum of 40 MB/s writing is possible. Otherwise, the specifications are pretty much the same as well as the prices (currently).

Extremely fast and suitable for professionals

If you absolutely do not want to compromise and want one of the fastest or best UHS-I memory cards on the market, we recommend the “Extreme Pro” from SanDisk. The write speed shoots up to 90 MB/s! It is, of course, a U3 memory card that is suitable for 4K videos. Here you can’t afford to make any compromises, so accordingly, the memory card is also a bit more expensive. But the performance can be worthwhile when used in combination with a corresponding camera.

UHS-II memory cards

As previously stated, cameras that support UHS-II memory cards (as of the end of 2017) are not very common. But for those that own such a camera, of course, they should also use a UHS-II memory card to exploit the full potential of the camera.

Both Transcend and SanDisk offer appropriate UHS-II memory cards with the usual (and still reasonably affordable) sizes of 32 or 64 GB. In general, the Transcend memory cards are a bit slower (180 MB/s writing as opposed to 250 MB/s writing at the SanDisk), but they are also a bit cheaper:

UHS-II with 32 GB
UHS-II with 64 GB

We have now completed the “SD part” of our memory cards purchase advice! Now let’s take a quick look at the other types of memory cards.

Canon EOS 5D Mark III Cameras have a slot for CF memory cards
Cameras like the Canon EOS 5D Mark III have a slot for CF memory cards

Compact Flash memory cards

Compact flash memory cards have in recent years been largely displaced by the much smaller SD memory cards, but some older cameras still require CF memory cards. In addition, some current professional DSLRs are equipped with slots for compact flash memory cards, because CF cards are equivalent to SD memory cards in terms of speed and are often superior.

Differences between Type I and Type II

There are Compact Flash Type I and Type II memory cards. The only difference is that Type II memory cards are slightly thicker than Type I memory cards; 5 mm in Type II as opposed to 3.3 mm in Type I. Most current CF memory cards are Type I memory cards because they can also be used in Type II slots. However, Type II cards cannot be used in a Type I slot.

Not to be confused: Compact Flash and CFast

Compact Flash memory cards and CFast memory cards are the same size and belong in the same “family”, but the newer (and faster) CFast cards work with a different connector. A CFast memory card CANNOT be used in a memory card slot for Compact Flash! If you want to use a CFast card, then the camera must explicitly support CFast technology.

Specific buy recommendations for Compact Flash and CFast memory cards

Rather slow and cheap

If you are working with an older DSLR that does not have a high continuous shooting speed, you do not need an excessively fast memory card. Here we recommend the SanDisk CF card from the “Ultra” series, as it is reasonably priced:

Fast as a fly in different sizes

For those with a current professional DSLR, saving money on a memory card should not be a priority, of course. One of the best CF cards available today is the SanDisk Extreme Pro, which is available up to 256 GB. The exact size can be selected on the product page on Amazon. The memory card has a write speed of up to 150 MB/s and is therefore extremely fast.

CFast memory cards with 128 or 256 GB

CFast memory cards are extremely expensive, but the best value for money at the time of this article is from Transcend. For the money, one can achieve tremendous read speeds of up to 510 MB/s and write speeds of up to 370 MB/s.

XQD memory cards

Finally, let’s take a quick look at the XQD memory cards, which are almost exclusively designed for users of Nikon cameras. Nikon is currently one of the very few manufacturers that offers storage slots for XQD memory cards. For the Nikon D5 or the Nikon D500, you need XQD memory cards. These are at the top in terms of speed and are comparable to UHS-II or CFast memory cards.

As for a specific product recommendation, we want to highlight another manufacturer other than SanDisk or Transcend. In the field of XQD memory cards especially, Lexar has made a name for itself, with a line of different card sizes (32, 64 or 128 GB) available:

Do you have questions?

We hope that we were able to answer all your questions about memory cards with this detailed memory card purchase advice article. If something is still unclear, ask questions in the comments! We’ll help you figure out which memory card is right to support your particular camera and meet your specific use.


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