How do I know if my Sandisk is Class 10?

Quick Answer

There are a few ways to identify if your Sandisk memory card is Class 10 or not:

  • Look for a “10” on the card itself or on the packaging – this indicates a Class 10 speed rating.
  • Check the specifications of the card – Class 10 cards will be listed as having a minimum write speed of 10 MB/s.
  • Test the write speed of the card using software like CrystalDiskMark – Class 10 cards will have write speeds of at least 10 MB/s.
  • Use the card in your device – Class 10 cards are optimized for HD video recording so try recording HD video to test.

What is a Class 10 SD Card?

SD cards are given speed class ratings from 2 to 10, indicating their minimum guaranteed write speeds. A Class 10 SD card has a minimum write speed of 10 MB/s, making it ideal for recording full HD video and continuous burst mode photography.

The SD Association created these speed classes to help consumers identify cards capable of certain write speeds. While Class 2, 4 and 6 cards are becoming obsolete, Class 10 represents the current standard for full HD devices.

Here is an overview of the different SD card speed classes:

SD Card Class Minimum Write Speed
Class 2 2 MB/s
Class 4 4 MB/s
Class 6 6 MB/s
Class 10 10 MB/s

As you can see, the Class number represents the guaranteed minimum writing speed in megabytes per second (MB/s). While in some cases a lower class card may perform at Class 10 speeds, the 10 rating indicates it is engineered to sustain at least a 10 MB/s write speed.

Why Use a Class 10 Card?

Here are some key reasons to use a Class 10 SD card:

  • Full HD video recording – Class 10 cards are optimized to handle the data rates required for smooth full HD video recording and playback. Lower class cards may result in dropped frames or corrupted footage.
  • Continuous burst mode photography – Taking sequential shots in burst mode requires fast write speeds to capture all images. Class 10 cards can handle this high data rate.
  • Quick file transfers – The faster write speeds allow for quicker file transfers to and from your computer.
  • Future proofing – As device capabilities continue improving, Class 10 will remain the standard for HD recording and photography.
  • Smooth performance – The fast write speeds reduce bottlenecks and lags when recording or viewing data.

In short, Class 10 SD cards provide a future-proof standard for full HD cameras, camcorders and high-end DSLRs. The faster write speeds allow them to smoothly handle large data files like HD video. Lower class cards may lead to choppy footage or slow transfers.

How to Identify a Class 10 Card

There are a few easy ways to determine if your SD card meets the Class 10 specification:

1. Look for Markings on the Card

Class 10 cards are clearly labeled with the number 10 on the card itself or on the packaging. You may see:

  • A C10 marking on the front of the card
  • Class 10 or C10 on the back near the contacts
  • A 10 within a circle on the packaging
  • Class 10 advertisement on the retail packaging

This numeric 10 marking distinguishes it as meeting the minimum 10 MB/s write speed. Unless specifically labeled, it should not be assumed to be a Class 10 card.

2. Check the Card Specifications

The technical specifications for your SD card found on the packaging or online product description should clearly indicate if it is Class 10. Look for phrasing like:

  • “Meets SD Class 10 specification”
  • “Minimum sustained write speed of 10 MB/s”
  • “Maximum transfer speed: 10 MB/s”

For validated Class 10 cards, this speed classification will always be highlighted in the specifications. Checking the specs is the most reliable method.

3. Test the Write Speed

To test the actual write speed, use benchmarking software like CrystalDiskMark or SD Card Tester Pro. These will measure the card’s sequential and random write speeds when transferring test files.

The benchmarks should indicate speeds at or above 10 MB/s for large sequential writes to conform to Class 10 performance standards. Small random writes may be slower.

Testing the speed yourself provides an objective measure, though comes with extra effort. Relying on the Class 10 markings is simpler in most cases.

4. Try Recording HD Video

The ultimate test is using the card in an HD camcorder or DSLR. If it can smoothly record and playback full 1080p or 4K video, the card is up to Class 10 standards.

Dropouts, corrupted footage or sluggish previewing likely means the card lacks the write performance expected from Class 10 models. Try a clearly marked Class 10 card to see the difference in recording capability.

This practical test demonstrates if the card can handle high bitrate HD footage – the key reason Class 10 cards exist. Just be sure to test non-critical footage in case of issues.

How is the Speed Rating Tested?

For a card to carry an official Class 10 speed rating, the manufacturer must have it certified based on standardized testing methods below:

1. CrystalDiskMark Benchmark

CrystalDiskMark is a storage benchmark used to test sequential and random read/write speeds. Per the SD Association compliance standards, a Class 10 card must reach a minimum of 10MB/s writing to the card sequentially.

2. Test File Method

This involves writing test files to the card in sequences to simulate HD video recording. Different file sizes and formats are used to evaluate worst-case performance. The card must sustain 10MB/s writes to comply with Class 10.

3. SD Association Certification

Card manufacturers can submit products to the SD Association for formal Class 10 certification. Their test labs will validate the benchmarks and ensure the card meets all requirements to advertise Class 10 capabilities. A certification number is provided if approved.

Certification is optional but ensures the manufacturer’s reported speeds were verified. Without formal Class 10 approval, speed ratings should be taken with some skepticism.

Beware of Counterfeits

There are counterfeit and knock-off memory cards that may falsely display Class 10 logos and markings. However, their performance does not meet official standards.

These fakes often:

  • Come from unauthorized dealers at prices too good to be true
  • Have logos and branding that appear irregular
  • Write at slower speeds than Class 10 according to benchmark tests
  • Malfunction or corrupt data when recording HD video

Reputable brands like SanDisk are more trustworthy. Purchasing from authorized retailers reduces the risk as well. If the price seems very low or the card underperforms, it may unfortunately be a counterfeit.

The safest bet is to buy directly from well-known brands like SanDisk, Samsung, Sony, Transcend, etc. Check that a Class 10 logo is both on the packaging and on the card itself for extra assurance.

Key Takeaways

To summarize the key points on identifying Class 10 SD cards:

  • Class 10 refers to a minimum sustained write speed of 10MB/s
  • Cards will be marked with C10 or Class 10 logos if certified
  • Check official product specs for the speed rating
  • Use CrystalDiskMark to benchmark performance
  • Test with HD camcorders to ensure smooth video recording
  • Avoid counterfeits by purchasing from authorized retailers
  • Genuine Class 10 cards enable full HD video and burst photo capture

Following these guidelines will help confirm your SanDisk or other SD card meets the performance demands of Class 10. Then you can rest assured it will handle your device’s most intensive storage needs.

Frequently Asked Questions

1. Will any SanDisk SD card work in my camera?

No, you need to match the SD card specifications to your device requirements. Key factors are capacity, speed rating, form factor, and compatibility. SanDisk offers a fit guide to find the right card for any camera or device.

2. How much better is a UHS-I vs Class 10 card?

UHS-I cards offer faster interface speeds over the SD bus, ranging from 50-104 MB/s. So UHS-I cards exceed Class 10 writes, but cost more. Class 10 may be sufficient unless you need the fastest read/write speeds.

3. What happens if I use a Class 4 card instead of Class 10?

A Class 4 card has a minimum sustained write of 4MB/s, well below Class 10’s 10MB/s rating. This may lead to choppy HD video recording, slow burst photo capture, or file transfer lags. Stick with Class 10 for better performance.

4. What is the lifetime of a Class 10 SD card?

Most Class 10 SD cards will last 5-10 years with normal usage before showing degraded performance. Higher endurance cards rated for more write cycles may last up to 20 years. Proper maintenance helps maximize the card’s usable life.

5. Can I use a Micro SD card with my DSLR using a SD adapter?

Yes, you can use a MicroSD in an SD adapter as long as its speed class and capacity meets your device requirements. Pay attention to the adapter speed rating, as subpar adapters can bottleneck performance.


Identifying if your SanDisk memory card meets the Class 10 specification is straightforward once you know where to look. Clear Class 10 markings on the card along with confirmed specs are key. Putting the card through practical testing for sustained write speeds erases any doubt.

With a validated Class 10 SD card from a reputable brand, you can achieve smooth HD video recording, fast burst image capture, and quick file transfers that lower speed class cards struggle with. Just be diligent checking for counterfeits and purchase from authorized retailers for guaranteed performance.

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