How to Format Ender 3 (Pro) SD Card? (Windows, Mac, Linux)

If you have recently bought an Ender 3 or an Ender 3 Pro, you must be excited about all the cool things you can print with your brand new 3D printer.

Unfortunately, just as with all pieces of new and exciting technology, one usually goes through a fair few problems before getting everything to work as intended, which is probably the reason behind you being here instead of enjoying your 3D printer.

The printer not reading the SD card is one of the most commonly encountered problems with the Ender 3 and the Ender 3 Pro and is often a result of formatting issues.

So, how to format an SD card in a way that would work with Ender 3 and Ender 3 Pro?

To make your SD card work with your Ender 3 or Ender 3 Pro, you need to set the partition table of the card to Master Boot Record (MBR) and format it with the FAT32 filesystem.

While the requirement of formatting with FAT32 is widely mentioned, setting the partition table to MBR is often overlooked.

Since this process can be considered to be quite technical for someone who isn’t familiar with how partition tables and filesystems work, let’s get down to how you can format your SD card in a way that meets these requirements.

Formatting Your Ender 3 (Pro) SD Card for 3D Printing

What makes this process hard for someone who isn’t familiar with computers is not knowing where to start. When the steps are laid out, executing it is very simple and does not require any technical knowledge.

As the steps you need to take to format your Ender 3 SD card varies depending on the operating system you’re on – we will be laying the steps out separately for Windows, Mac, and Linux.

Let’s start with Windows.

  1. Start by bringing the Disk Management window up. You can do this by right-clicking the Start Menu and clicking Disk Management in the menu that comes up.
  2. Find the SD card in the lists of disks (you should be looking at the bottom pane as the top pane is the list of volumes and not disks). If the labels aren’t helpful, you can figure out which disk is the SD card by looking at the capacity of the disks.
  3. Right-click the volume(s) that belong to the SD card (they are listed right next to the disk) and delete them. Be warned that this process will wipe all of the data on the card.
  4. Upon successfully deleting all the volumes, you should see a pane that says “Unallocated” next to your SD card and no other volumes, which confirms that you successfully deleted all the volumes.
  5. Now, right-click the SD card itself and select Properties.
  6. Click the Volumes tab in the dialog, and look at the partition style line. If it shows Master Boot Record (MBR), move to step 11. You can close the dialog and go back to the Disk Management window after gathering this information.
  7. Right-click the Start Menu, choose Windows PowerShell (Admin), and then type diskpart in the command line that came up.
  8. When the prompt starts showing DISKPART>, input the command select disk X, where X is the number of the disk. You can find this number by looking at the Disk Management window from earlier.
  9. Upon successfully selecting the disk, you will see the output Disk X is now the selected disk. At this point, all you have to do is to input the command convert MBR. Upon success, you should see the output DiskPart successfully converted the selected disk to MBR format.
  10. To confirm that the process was successful, right-click the disk in Disk Management, go to Properties, and then go to the Volumes tab once again to check the partition style. If it’s showing Master Boot Record (MBR), all is good.
  11. Bring the Disk Management window up, right-click the box that shows Unallocated, and choose New Simple Volume. Click Next until you reach the Format Partition dialog, and enable the Format this volume with the following settings radio button. Set file system to FAT32 and conclude the process by clicking Next and Finish, respectively.

Now, let’s lay out the steps that you should take on Linux.

  1. Start by opening up a Terminal window.
  2. Install gdisk if you don’t have it already, with the command sudo apt install gdisk.
  3. Input the command sudo fdisk -l to see all of the disks that are currently available, and find out which one your SD card is by looking at the capacities of the disks.
  4. Input the command sudo gdisk <diskpath> where diskpath is the path of your SD card. An example of this would be sudo gdisk /dev/sdb.
  5. Now, you should see whether your SD card has the MBR or the GPT partition table.
  6. Use the command x to bring up extra functionality.
  7. Create protective MBR with the command n.
  8. Use the command z to destroy the GPT data structure on the disk. Be warned that this process will cause a loss of data.
  9. Proceed by inputting the letter Y.
  10. If prompted with Blank out MBR, proceed with Y.
  11. Proceed with sudo fdisk <diskpath> and input the command n and accept all the defaults by pressing enter until the dialog is over. After that, input the commands t, b, p, and w, respectively. This process will create a FAT32 partition on your SD card. Use the command fdisk -l to verify that the partition is there, with a name such as /dev/sdb1.
  12. You can now exit fdisk and input the command sudo mkfs.vfat -F 32 -n <name> (an arbitrary name will do) <partitionpath> (/dev/sdb1 for instance). As an example, sudo mkfs.vfat -F 32 -n SDCard /dev/sdb1.

Mac users can utilize the same steps outlined for Linux as both gdisk and mkfs.vfat can also be installed on BSD Unix through homebrew. The fdisk -l command can be replaced with diskutil list instead, which will allow you to locate the path that belongs to the SD card the same way that the fdisk -l command does on Linux.

The mkfs.fat (the utility is called mkfs.fat instead of mkfs.vfat in dosfstools, but they are the same) utility is a part of the dosfstools package, which is what you will need to install through homebrew to get access to the mkfs.fat command.

Choosing an SD Card for Your Ender 3 (Pro)

As long as you ensure that the SD Card you’re purchasing is a Micro SD, it should work just fine with your Ender 3 or Ender 3 Pro.

That being said, some users have reported that they have experienced issues with SD Cards over 32GB in size, so it may be a safer bet to buy one that’s smaller in capacity.

As 3D printing files are rather small (mostly in the kilobytes), even a 2GB SD card will do just fine, so there isn’t much of a reason to go for high-capacity cards anyway.

Wrapping Up

Even though the SD card not being recognized by your Ender 3 or Ender 3 Pro can seem like a big problem at first, it’s actually an issue that you can solve rather quickly with the correct information.

As long as you ensure that you are using the MBR partition table and the FAT32 filesystem, there is no reason for your SD card not to be read by your 3D printer unless the card itself is faulty.

We hope that the steps we have laid out for you have been simple to follow and helped you to get your 3D printer working in the quickest way possible.