When you're purchasing a new memory card, the card's "read" and "write" speed is an important spec. If it's too slow, you might pass on the card; if that number is big enough, you break out your wallet. But are those speeds accurate? In this video, Tom David Frey of Tom’s Tech Time tested 10 different microSD cards to see how the advertised speeds on the box compare to real-world performance. The results are mostly disappointing... but not surprising.

Frey tested the top-of-the-line microSD cards out there—all 4K-ready, speed class 10 and UHS class 3. And while we wish the test involved regular SD cards, CF cards or XQD cards, since those are more relevant to photographers, the difference between the cards' read/write speed and real-world performance is still telling. Plus, drone photographers need some love too.

The cards tested include: The SanDisk Extreme PRO, Sandisk Extreme, Transcend Ultimate 633x, Samsung PRO, Sony SR-32UZ, Kingston, Panasonic, Toshiba Exceria Pro, Verbatim, and Patriot EP Series in either 16GB or 32GB sizes. Here are the contenders alongside their advertised read and write speeds:

Frey performed two tests. First, he used a USB 3.0 card reader and ran several programs to test the actual read/write speeds. Then, he took a 4.1GB video file from his hard drive and copied it to each of the cards in turn to gauge real-world write speed.

So... how did these cards perform in real life? All of them (except Panasonic, which doesn't give read and write speeds...) advertise read speeds of 90MB/s and up, and the fastest of them claim a write speed of 90MB/s. But not a single card topped even 80MB/s read speed, and the fastest write speed reached was 78.81MB/s by the SanDisk Extreme PRO.

The good news is that some of the cards actually outperformed their advertised write speeds, but none of them were the cards claiming lightning fast 90MB/s write.

You can see all of the results for yourself at the 7:30 mark of the video.