Before you can use an SD or microSD card, it has to be formatted (many come pre-formatted out of the box). To keep it compliant with SD Association specs, which minimizes the risk of your camera having problems with it, it's important to choose the correct filesystem to format it with. So here's a guide on how to format SD and microSD cards on Mac. First is the quick version; after that is a more detailed step-by-step guide. And I've also included an alternative approach using the SD Association's SD card formatter.
- Connect your SD card to your Mac using a card reader
- Open Disk Utility app
- Select your SD card
- Choose Erase function
- Enter SD card name (optional)
- Choose filesystem format. If 64GB or larger, choose exFAT. If 32GB or smaller, choose FAT32.
That was the quick version. Here's the more detailed version. The good news is that you don't have to download some expensive app to do it--everything you need is already there as part of the Mac operating system.
First, though, I should point out that if you're using your SD card in a camera, it's best practice to format the card in the camera itself. That way the camera can set it up how it wants and expects it to be, and it reduces the risk of filesystem issues interrupting your shooting. All cameras have a "format card" function (sometimes it's called something similar).
But if you want to go ahead and use format your SD card on your Mac, here's how to do it. Before starting, make sure you've saved any data you want to keep from the card, because formatting the card will delete all of the data on it.
Connect your SD card to your Mac
There are different ways to do this. Some Macs come with a built-in SD slot. If you have one of those, you can insert the SD card directly into that. If you're using a microSD card, put the microSD card into an SD adapter cartridge (it probably came with one) first, and then put that into the SD slot on your computer. You can also use a USB SD card reader.
Open Disk Utility App
Disk Utility is part of the Mac OS X operating system, so you don't need to download or install it. You can find it in your Applications folder under the Utilities subfolder (Applications > Utilities > Disk Utility). Or you can use Spotlight (the magnifying glass icon at top right of your screen) to search for it by clicking on the icon and then typing "disk utility".
Identify Your SD Card
On the left side of the Disk Utility's screen is a list of the various drives in your Mac and connected to it. So it will show your Mac's internal drive as well as external drives. The SD card should show up in the External section. If it hasn't been formatted before, it might have a name like "NO NAME" or "UNTITLED". If you click on it, you'll see how much storage it is. Make sure that it matches what you expect--that is, if you're inserting a 64GB SD card, make sure the capacity is showing as 64GB or close to it. If you're seeing something like 1TB instead, you've selected the wrong drive from the list.
Choose Erase Function
From the list of functions at the top, choose Erase. You'll get a popup warning you that you're about to delete everything on the card.
Enter SD Card Name
In the Name field, you can assign a name to the card. This is an optional step--it will work just fine if you leave it as NO NAME or UNTITLED--it's just a convenience issue to display a friendly name when you're viewing it in Finder or making sure you're importing from the correct card when ingesting images into Lightroom, for example. Keep the name short and simple--any long names or special characters will get rejected. Perhaps something like SDCARD1 or GOPRO, for example.
Choose the Filesystem Format
Under the Format drop-down menu, you have several options. The only ones we're interested in here are MS-DOS (FAT32) and ExFAT. Which to choose depends on what size storage cards you're using. If your SD card is 64GB or larger, choose ExFAT. If your SD card is 32GB or smaller, choose MS-DOS (FAT32).1
It will say it's unmounting it and then, after a few moments (or perhaps a little longer), you should get a message that the process is complete.
And with that, you're done and the card is ready to use.
As I mentioned earlier, it's best practice to format memory cards in the camera, but if you want to format your SD card on your Mac, this is how you do it.
Things to Know
Older versions of Mac OS don't support exFAT. Specifically, exFAT support was added to Mac OS X in version 10.6.6, which was Snow Leopard released in 2009. If you have any of the newer versions--Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra, or Mojave--those all have native exFAT support baked in.
It's a good idea to be extra careful when selecting your SD card from the list. You don't want to accidentally format another drive.
When you format a memory card, you should be prepared for everything to be deleted from the file. But in reality, it might still be possible to recover files from the card even after formatting. If you find yourself needing to try, take a look at my post on how to recover files from SD cards.
Alternative Method: SD Card Formatter
There's an alternative method to formatting an SD card on your Mac that involves downloading a free SD card formatter provided by the SD Association. It's very simple to use, with just a single screen that looks like this:
It does have some small benefits over using Disk Utility. One is that it automatically detects what is and isn't an SD card, and it won't make non-SD cards (or non-microSD cards) available. Which means there's less chance of accidentally erasing the wrong drive. Another is that it will automatically detect the size of the card and choose the appropriate filesystem. If you insert a 64GB card, it will only allow you to format it to SDXC specifications using exFAT. So it takes out any risk of selecting the wrong option. And they do provide this warning:
It is strongly recommended to use the SD Memory Card Formatter to format SD/SDHC/SDXC Cards rather than using formatting tools provided with individual operating systems. In general, formatting tools provided with operating systems can format various storage media including SD/SDHC/SDXC Cards, but it may not be optimized for SD/SDHC/SDXC Cards and it may result in lower performance.
It's free, and you can find it here. There are versions for Mac and Windows.
- It is entirely possible to format the SD card with the other filesystem (eg. a 32GB card with ExFAT or a 128GB with FAT32), but it can be risky to do that with some cameras. Some cameras will throw an error if the card isn't formatted with the system it expects as defined in the SD Association's specs. So if you do want to go against the specs, it's worth making sure that your camera will accept it before heading off to shoot. ↩