Hello Brigitte, its size is of no importance as long as it is inserted into an SD port. There are two physical types, the larger SD and the smaller microSD, which also fits into a specific microSD port. The microSD is actually smaller, about the size of a phone microSim or nanoSim, whereas the SD is about the size of a thumb, so it's easy to see the difference. I hope this has helped you. Bonne journée.