This is calculation difference between manufacturer and your PC, please Google 'Memory card capacity' to get more information. Your PC says 1GB = 1.073741824 Billion bytes where Market Defines 1 GB = 1.00 Billion bytes.
Regarding the speed： The speed in our detailed picture is the highest speed of the memory card, and please use a USB3.0 card reader to plug in the 3.0USB interface of the computer to test, otherwise the speed will be lower
