How to format an microSD / SD card on Windows or Mac OS X

Article HD25900, June 26, 2015

One way to format is using the SD card association's formatter utility at


Sometimes it is a good idea to get a fresh start with an originally blank microSD / SD card, assuming no valuable charts or singularly irreplaceable data is stored on the card. You may do this by resetting the file system on the card which removes all existing files.

Computers with Windows and Mac OS X have built-in utilities to format microSD or SD (or other media type) cards. These may be adequate for your use and there are some web sites you can find with searches such as "How to format SD card on Windows" which will explain the method.

An alternative is to use a free simple app provided by the SD Card manufacturer's organization. Download and install the Windows or Mac app at the bottom of this web page:

The web site also posts nice simple PDF "how to" documents on using their formatter utilities. Follow the instructions in those documents.

Generally, you will want to do a full and thorough reformat of an SD card, not the "Quick Format" option.

The SD card format chosen should (preferably) be simply "FAT" (file allocation table, 16 bit); otherwise accept FAT32. So far, in our Fugawi related purposes, we have had no use for the exFAT file format system. Formatting as FAT provides the greatest range of compatibility (disregarding efficiency / optimization), at least for cards with a capacity 32 GB or less.

If you really must use a built-in Windows method, right-click the correct drive letter representing the microSD or SD card and select Format.

Right-click an SD card attached to Windows 81 and choose Format

Select FAT or FAT32 from the drop-down menu (never choose NTFS, or Mac OS Extended). Enter an arbitrary name for the card, and un-check / de-select the Quick Format option so a full format is done instead. Formatting may take a minute or more. If any error messages prevent formatting, the microSD / SD card in use may be problematic and so another card should be tried.

Example of an F drive SD card about to be formatted

And on Mac OS X, you use the standard app at Finder | Applicatons | Disk Utility to format an SD card.

Mac OS X disk utility Erase tab