1. 4GB=approximately 3.6GB-3.8GB.
2. 8GB=approximately 7.2-7.6GB.
3. 16GB=approximately 14.4GB-14.8GB.
4. 32GB=approximately 28.5GB-30GB.
5. 64GB=approximately 58.5GB-60GB.
6. 128GB=approximately 110GB-120GB.

This is calculation difference between manufacturer and our PC, just for you reference.

1. If the memory card needs to be formatted after inserting it into the device, you can try inserting the memory card into the computer and formatting to repair the memory card.

2. If the memory card cannot be read after it is loaded into the device, you can try to install the memory card on a different device to check whether it can work normally (such as computer, mobile phone, MP3, etc.). If it works normally on other devices, there may be a problem with the TF card interface of the original device.

3. If you pull out the memory card while it is running, it may damage the memory card or damage the files in the memory card. Be sure to select “Eject” on your device every time you remove the memory card.

Notice:

1. Please check the maximum supported capacity of the device using TF, and many devices only support TF cards with a capacity below 4G;

2. The memory card system uses the FAT32 disk system by default, and the maximum single write is 4GB at a time. If you need to store a single file over 4GB, it is recommended to reformat the memory card and set it to the exFAT file system (it can also be set to NTFS, but it will do great damage to the TF card).