Format an SD card for an Android smartphone or tablet either on your Android device directly, or on a PC. The process on an Android device is the same for Android 4.4 or later. On a PC, it's the same for Windows 7, 8.1 and 10.
Formatting on an Android Device
Insert the SD card in the Android smartphone or tablet's SD card slot. Tap the Apps icon and tap Settings.
Tap General and then Storage. Tap the Format SD Card option at the bottom of the screen. If you don't see the Format SD Card option on your device, tap Unmount SD card to reveal it.
Tap Format SD Card when the dialog box warns that any data on the card will be removed forever. A second dialog box opens, warning that you are about to erase everything. Tap Erase.
Wait a few seconds for Android to format the SD card. When the Erasing SD Card notification disappears, the formatting is complete and the SD card is mounted to the device, meaning it can now be used. Tap the Unmount option before removing an SD card from an Android device.
Formatting on a PC
Connect the SD card to your computer, either by inserting the card directly into a computer's SD card slot, using a USB adapter, or by connecting a device containing the card to your PC.
Select the SD card in Windows Explorer. On most computers, it's listed as drive (D:). Open each folder and copy any files you want to save to a folder on your computer's hard drive.
Type Disk Management in Windows Search and select the Create and Format Hard Disk Partitions utility. Select the SD card in the list of connected disks.
To ensure it's the correct drive, the SD card has the same drive letter -- (D:) -- as it did in File Explorer. SD cards almost always use the FAT32 File System. The capacity is slightly less than that displayed on the card's label.
Click the Action menu, select All Tasks and then click Format.
To ensure that the data being deleted won't be easily recoverable, deselect the Perform a Quick Format option by clearing its check box. A Quick Format takes only a few seconds, while a full format takes much longer. When you're using the SD card in an Android device, leave the other settings at their default values. Click OK.
Click OK at the dialog box warning you that all data will be erased. When the formatting is complete, copy any files that you plan to use with your Android device back onto the SD card. Disconnect the SD card and insert it into an Android smartphone or tablet.