True SD Card Capacity & Speed

Alan Robinson

About this app

This "short" endurance test confirms if your SD card is valid and reliable OR if it's a counterfeit that has way less storage space than advertised. It fills your card with carefully designed files that the app can then verify to ensure that what's written to your flash card can be read back reliability. It also measures read & write speed at the same time, because, why not?

It's not the most pretty app because the focus has been instead on real-world testing and good algorithms. It is, however, easy enough to use. The only way to know your card is good is to fill it to the advertised capacity. Typically this takes less than an hour but can be longer if the card is particularly slow or enormous. Piece of mind is worth the wait and there are no shortcuts to it!

You can also test your phone's internal storage. With USB-OTG you probably can test thumb drives too, depending on how your phone works.

Note: English only. The default settings are reasonable, however, so you may just proceed to "start test".

Ratings and reviews

I am so glad I ran this test! I bought a cheap SD card from Amazon. I didn't know any better. It was a total accident that I found out about fake SD cards. I was just comparing brands to figure out which one to buy & came across the info. (Thanks, Google!) I went ahead and got one just to find out for myself. Phone read it as a 1 TB card. The test found that nearly 75% of the written files became corrupted. This app saved me from likely losing countless priceless memories!!

Excellent. Very fast and easy to use. A cheap 32gb card took about 40 minutes to test and it was all as advertised. On my phone it worked at 1gb per minute to write and much faster to read. This is much quicker than using a PC to check micro SDs. If you use your phone for anything else the App pauses and you can just restart it. I tested a suspect 32gb cctv card. Files not readable. I guessed it was fake. The App found this and trashed the card, which was not reliable anyway.

A basic no frills app that writes multiple large files to the card reporting write speed then verifies all files and reports read speed and errors or corruption as it checks them. Can take many hours but it does do a thorough test. I used to test by filling with photos then looking at each one and that was a real pain. It is easy enough to use and worth reading the warnings provided.

What's new

Now with android 14 support.