How to Partition a USB or SD Card With Disk Management in Windows 10

To split a USB flash drive or SD card in Windows 10, shrink an existing volume in Disk Management and create a new simple volume in the space that becomes unallocated. Back up the card first: formatting erases the selected partition, and selecting the wrong disk can affect unrelated files.

Windows 10 version 1703 and later supports multiple USB partitions, though a reader or target device may show only one. See Microsoft’s Disk Management guide for the built-in tool’s volume actions.

Before you begin

Copy important files elsewhere. In Disk Management, identify the removable disk by its capacity and current drive letter; disk numbers can differ across PCs. Shrinking an eligible volume normally keeps its existing files, but a backup is still essential.

Disk Management can shrink NTFS or unformatted partitions, not FAT32 or exFAT volumes. If Shrink Volume is unavailable, check the file system. On a FAT32/exFAT card, the clean-start option below erases the device and should be used only after a verified backup.

Partition the USB drive or SD card

1. Connect and identify the device. Insert the USB drive or SD card reader. Open Disk Management and match its capacity and drive letter before making changes.

   

2. Open Disk Management. Right-click Start and choose Disk Management, or press Windows + R, type diskmgmt.msc, and press Enter. In the lower pane, right-click the device’s existing volume and select Shrink Volume—not the disk label or an internal partition.

   

3. Enter the shrink amount. Type how many megabytes to free. For example, 16,384 MB is about 16 GB. That amount becomes unallocated space; the original volume keeps the remainder. Windows may offer less than the free space shown because some files cannot be moved.

   

4. Shrink the volume. Select Shrink. When the map refreshes, check that the same disk shows the original partition and a black Unallocated area. Confirm the sizes before proceeding.

   

5. Start a new volume. Right-click the unallocated area on that disk and select New Simple Volume. This wizard uses the free space for the new partition; it does not reformat the volume you just shrank.

   

6. Set the volume size. Enter a size in MB or accept the maximum to use all remaining space for the second partition. To make more than two partitions, leave some space unallocated and repeat the wizard later. Select Next.

   

7. Assign a letter. Choose an unused drive letter, or mount the volume in an empty folder. A letter makes it accessible in File Explorer. Select Next.

   

8. Choose a format and finish. Use NTFS for a Windows-focused volume, exFAT for compatible removable devices, or FAT32 only when an older device requires it; FAT32 cannot store a single file larger than 4 GB. Choose a label. Quick Format is normally sufficient for a new partition. Select Next, review the summary, and select Finish. Formatting erases data on that new volume, so verify the disk and size first.

   

Check the partitions or troubleshoot

Confirm both volumes appear as Healthy on the same disk, then check This PC in File Explorer. If a healthy partition is missing there, right-click it in Disk Management, choose Change Drive Letter and Paths, select Add, and assign an unused letter. A RAW volume needs formatting before use; do that only if it contains no data you need.

If the device is FAT32 or exFAT, or Windows cannot shrink it, you may need to erase and recreate the layout. After backing up, right-click the existing volume, choose Delete Volume, then create smaller volumes from the unallocated space if the device allows multiple partitions. Deleting removes the volume’s contents. Microsoft’s shrink-volume guidance explains the NTFS limitation and why unmovable files can restrict shrinking. Its multiple-partition USB guidance covers Windows 10 version 1703 or later and the FAT32 4 GB file-size limit. Check the camera, console, or other device’s format requirements before copying files.