SD cards are useful for storing and transferring documents between computers and MP3 players and are commonly used in many digital cameras. Formatting an SD card on a Mac for use in digital cameras, other Macs or even PCs is done using the Disk Utility application.
Plug your memory card reader into a USB port on your Mac. Insert the SD card into the memory card reader's SD slot, and the SD card will mount on your Mac desktop.
In an open Finder window, single-click "Applications" in the Side-Bar and scroll down to find the Utilities folder. Find Disk Utility in the Utilities folder and double-click the "Disk Utility" application to launch it.
In the opened Disk Utility application, single-click to select the SD card in the left-hand Drives column. Then, single-click to select the "Erase" button in the top row of radio buttons. Select the format you wish to use to format the SD card on the "Volume Format" pop-up button. Use Mac OS Extended (Journaled) for use on Macs and MS-DOS (FAT) to share the SD card with both Macs and PCs or digital cameras. When you have finished selecting the formatting options, click "Erase."
A new dialogue box will pop up in "Disk Utility," asking if you are sure you wish to erase the SD card. Caution: Erasing the SD card will permanently erase any files. Make sure you have backed up any file you wish to keep. To continue with the formatting process, click "Erase."
Once the SD card has been erased, it will mount on your Mac desktop just as any other removable drive.
Erasing an SD card will permanently erase any files on the disc. Back up any file you wish to keep.