Capacity 16GB = approximately 14GB-15GB 32GB = approximately 28GB-30GB 64GB = approximately 58GB-60GB 128GB = approximately 119GB-120GB 256GB = approximately 224GB-240GB 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 1GB = 1.00 Billion bytes.The pursuit of the perfect person is not recommended to buy. Speed Test (1). The speed show on our link is test by Sandisk/Samsung or by our professional instrument, you’d better use 3.0 interface and 3.0 card reader, then you can get a nice speed. (2). Speed is influenced by many different factors, interface, computer condition, test software ,systems ,use , etc . (3). If you test a low speed by yourself, please donot worry, you can try another instrument to test(need 3.0 interface and 3.0 card reader). And if you always get the same low speed, you can retrun the goods, then we refund you all money. (4). We can 100% promise that our product are all 100% original, there is a security verification label on each package. (5). Once you place your order, it mean you had read and agree with my description.