64GB microSDXC Card Capacity Lower than Advertised

[azureskies]

I bought a G.Skill FF-TSDXC64GA-U1 64 GB microSDXC card yesterday and it doesn't have a capacity of 64GB. My computer reports the card has 62,696,456,192 bytes unformatted which is 1,303,543,808 bytes less than the 64,000,000,000 bytes I was expecting. All the microSD cards I have bought so far have met the advertised capacity, so I'm wondering why this one doesn't.

Does anyone here have any idea? As far as I know, these cards don't have any special reserve capacity for wear levelling or anything fancy like SSDs do, so I think the full capacity should be available.

[GSKILL TECH]

No, any storage device will have missing capacity. For microSD card, there is reserved capacity for SD compatibility specifications. To format SD card, you should use SD Formatter because with other software can treat flash like a hard drive and completely erase the reserve capacity, then you can have compatibility issues and corrupt SD cards that no longer work.

[azureskies]

I see. I wasn't aware of the reserved capacity of the SD specification. I'd be happy if there was evidence of that part being beneficial, a way of monitoring it, or at least a way to see its capacity. It seems to be some value determined by the manufacturer.

The storage devices I have bought so far from manufacturers either exceed their labelled capacity or are just a little below it. I have decided to return the card, since my research show some other brands don't have such a big difference between their marked capacity and the usable capacity.

Thank you for your time.