SanDisk is a well-known name in the flash memory industry. Founded in 1988, they developed the first flash-based SSD. They were later acquired by Western Digital in 2016, before being spun off as a public company in early 2025.
SanDisk is a name I’ve long been aware of, and one that — prior to this project — I was biased in favor of. I have a number of single-board computers that take microSD cards, and I typically defaulted to the SanDisk Ultra 16GB for their storage — and most of the time, had no issues with them. And since they’re such a major brand, I wanted to make sure they were properly represented in this project.
On the performance testing front: results were kinda all over the place. Random read speeds were definitely this card’s strong suit, but even those were inconsistent. Here’s how things shook out:
- Sequential read: Sample #2 got a score that was a little higher than the others, coming in at the 81st percentile (as of the time of this writing). The other two samples came in at the 37th and 46th percentiles. I’ll note that the spread here (the difference between the worst-scoring sample and the best-scoring sample) is only about 8.5MB/sec — less than one quarter of a standard deviation apart — but so many cards scored close to 90MB/sec that it doesn’t take much to go from the 46th percentile to the 81st percentile.
- Sequential write: Sample #3 performed significantly better than the others, coming in at the 56th percentile. The other two samples came in at the 34th and 35th percentiles.
- Random read: Sample #3 performed significantly worse than the others, coming in at the (still-respectable) 71st percentile. The other two samples scored at the 97th and 99th percentiles.
- Random write: There was kind of an uneven spread here, with sample #2 scoring worse than the other two samples. Sample #2 scored in the 51st percentile, while the other two samples scored in the 56th and 64th percentiles.
These cards bear the Class 10, U1, and A1 marks. Performance was good enough for the Class 10 and U1 marks, but not enough for the A1 mark. However, I’ll throw in my standard disclaimer here: my performance testing methods do not align with those prescribed by the SD standard. It’s possible that they would have done better had they been tested under proper conditions.
This is another UHS-I card that advertises speeds higher than what should be possible under the UHS-I standard: the package advertises (in Chinese) “speeds up to 120MB/second”. To give this card a fair chance, I tested one of them using one of the SanDisk MobileMate readers, but it didn’t seem to perform significantly better with this reader than it did with the Togconn or JJC readers.
On the endurance testing front:
- Sample #1’s first error was an address decoding error during round 1,906. It died when I plugged a new card reader into the neighboring USB port. (EmbeddedTS once tested a number of SanDisk cards and noted that they had a tendency to die when exposed to a brownout — and I suspect that this is what happened here.) Up to that point, less than 0.1% of the card’s sectors had been flagged as “bad”.
- Sample #2’s first error was an address decoding error during round 1,584. It died at the same time as sample #1 — when I plugged in a new card reader into the neighboring USB port. Up to that point, less than 0.1% of the card’s sectors had been flagged as “bad”.
- Sample #3’s first error was an interesting combination of errors that occurred during round 396. It resembled an address decoding error (where the data was shifted by one sector); however, the first four bytes of each sector were set to all
0x00‘s. This lasted for 7 sectors, followed by 2,048 contiguous sectors where the data was shifted by one sector. It continued working just fine for about another 2,800 read/write cycles, when it simply stopped responding to commands.
Overall?
- Skimp was above average.
- Sequential write speeds were below average; however, as a whole, performance was above average.
- Endurance was pretty below average. (As of the time of this writing, the average number of read/write cycles to the 0.1% failure threshold is sitting at about 7,500 — and none of the three samples even made it close to that mark.)
So I think my verdict here is that these cards are just OK. There are better options out there, especially if endurance is important to you. (In the 32GB category, my current favorite is the Kingston Canvas Select Plus — it did worse in skimp and random read speeds, but better in pretty much everything else — including endurance.) However, if random read speeds are the most important factor to you, then this is the card to go with.
July 7, 2025