The card reader should support SD cards up to 1 TB in size. That's the maximum under the SDXC specification. May I ask what you plan on using the SD card for? If you plan on using it for expandable storage, you're better off installing a second SSD inside the laptop, which will provide better reliability and much faster transfer speeds. Your model supports one 2.5" SATA drive and one M.2 2280 drive, the latter can use either the SATA or NVMe interface. If your storage needs require disconnecting the drive, then go with an external hard drive/SSD with a USB 3.0 interface. Personally, the card reader is just there for transferring files to/from another device, like a digital camera, MP3 player, tablet, phone, etc., and really isn't meant for permanent storage expansion unless all other options are unavailable. Also, the card reader is likely on a USB 2.0 bus, capping the speed to about 30 MB/s, so don't expect the transfer speed that the SD card is rated for.
It looks like this lap top is compatible with SDXC. Does anyone know the maximum capacity specification on this computer? I want to purchase the largest SD card possible.  [IMAGE]  
Inspiron 7580 SD Card Size