
Lexar High-Performance 633x 256GB
Score: 60/100
SanDisk Ultra 64GB
Score: 75/100Rankings

The SanDisk Ultra 64 GB SDXC card delivers solid read performance up to 99.5 MB/s and broad compatibility with major camera brands. Write speeds hover around 16-22 MB/s and it lacks higher video class ratings, limiting 4K use. Suited for casual to semi-professional photographers.

Lexar's 256 GB 633x microSDXC offers up to 100 MB/s read speed, a V30 rating, and includes a micro-SD to SD adapter for versatile use. Its slower 45 MB/s write speed and lack of waterproofing limit high-end video applications. Suitable for smartphones, tablets and action cameras where large capacity and broad compatibility are priorities.
| Attribute | ![]() | ![]() |
|---|---|---|
256 GBbest | 64 GB | |
100 MB/sbest | 80 MB/s | |
45 MB/sbest | 10 MB/s | |
| ↓ lower better | 453.6 g | 4 gbest |
— | 10 yearsbest | |
| ↓ lower better | 1.02 mmbest | 2.3 mm |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Storage(1) | ||
Capacity (GB) | 256 GB | 64 GB |
Performance(3) | ||
Read Speed (MB/s) | 100 MB/s | 80 MB/s |
Write Speed (MB/s) | 45 MB/s | 10 MB/s |
Speed Class | C10 | Class 10 |
Design(3) | ||
Form Factor | microSDXC | SDXC |
Weight (g) | 453.6 g | 4.0 g |
Thickness (mm) | 1.02 mm | 2.3 mm |
General(1) | ||
Compatibility | wide compatibility with any UHS‑I device while remaining backward compatible with Class 10, V10 and U1 standards | Canon, Nikon, Sony, Fuji, Olympus, Panasonic |

Products in the top-left offer the best value (high score, low price).

Professional testing shows the Lexar 633x card delivers real-world read speeds near 97 MB/s and write speeds around 69 MB/s, surpassing its advertised specifications and confirming its suitability for 4K video capture. Reviewers acknowledge its solid mid-range performance but point out that newer Lexar BLUE models provide higher peak speeds, making the 633x less compelling for users seeking top-tier throughput.
Everyday users praise the large 256 GB capacity, the included SD adapter for easy file transfer, and the peace of mind from the lifetime warranty. They also highlight the card's reliable 4K video performance and compatibility with a wide range of devices. However, some users note the write speed feels modest compared to newer offerings, and the lack of UHS-II support limits its appeal for high-end professional use.



Professional reviewers view the Ultra as a budget-friendly option that delivers solid read performance but falls short on write speed. They note its suitability for users with modest bitrate needs while recommending the Extreme or Extreme Pro lines for demanding video or burst photography.
Everyday users generally express high satisfaction, praising the large capacity, reliability, and seamless camera compatibility. Complaints are minimal, with most reviewers reporting error-free operation and quick delivery.