Formatting the SD card will erase all its memory which means you will lose access to all your stored information. It is better to take a backup of this data first. Google will back up your SD card and other phone data for free.

Should I format my SD card in my phone?

Now that the data has been backed up, we can move on to formatting the microSD card. Formatting is not necessary, as the card is staying with you. If you chose to mail the microSD card in with the phone, I highly recommend formatting your card.

What does it mean to format an SD card?

You can format an SD card using Windows, Mac, and Android devices, and likely your digital camera too. Formatting an SD card will erase everything on it, including the junk or corrupted files you usually can’t see.