Free online VDI to VHD converter

A VDI disk must be converted when a virtual machine platform or Windows tool accepts VHD but not VirtualBox's native format. The conversion moves the guest disk to another virtualisation environment without reinstalling the operating system, although the virtual machine configuration is not converted.

What the VDI format is

VDI, or Virtual Disk Image, is Oracle VirtualBox's native virtual hard-disk format. It stores the guest's partition table, boot data, operating-system files, applications, and user data in a virtual disk container.

VirtualBox can create dynamically allocated or fixed-size VDI files. Snapshots use differencing disks, so the current guest state may be stored in a child image rather than the original VDI. A VDI file is commonly stored in the VM's folder under VirtualBox VMs, but its location can be changed.

What the VHD format is

VHD, or Virtual Hard Disk, is Microsoft's legacy virtual-disk format. Hyper-V, Microsoft Virtual PC, Windows disk-management tools, and some backup applications can attach or create VHD files. VHD contains a virtual disk's partitions and filesystems; it does not convert the files inside the guest individually.

VHD supports fixed-size and dynamically expanding disks. Its practical maximum capacity is about 2,040 GB; use VHDX for larger disks when the destination supports it. VHD is commonly useful for moving a VirtualBox disk to Hyper-V or for mounting the image with Windows-compatible tools.

How to convert a VDI file to VHD

Using VirtualBox

1. Shut down the guest operating system rather than suspending it, and close VirtualBox. Do not convert a disk while it is being written.
2. Back up the VM directory. If the VM has snapshots, do not convert only the original base image: use the current differencing image as the source, or delete or merge the snapshots through VirtualBox first. Keep every file in the disk chain available.
3. Open a terminal or Command Prompt containing VBoxManage, which is installed with VirtualBox, and run:

VBoxManage clonemedium disk "input.vdi" "output.vhd" --format VHD

Use full paths when the files are not in the current directory. Older VirtualBox releases use the equivalent command:

VBoxManage clonehd "input.vdi" "output.vhd" --format VHD

The command creates a new image and leaves the source unchanged. To create a fixed VHD, add --variant Fixed:

VBoxManage clonemedium disk "input.vdi" "output-fixed.vhd" --format VHD --variant Fixed

Without that option, VirtualBox normally creates a dynamically expanding VHD. Check the output with:

VBoxManage showmediuminfo disk "output.vhd"

Create a new VM on the destination platform and attach the VHD as its existing virtual disk. In Hyper-V, use New → Virtual Machine → Connect Virtual Hard Disk → Use an existing virtual hard disk.

Using QEMU

QEMU's qemu-img can read VDI and write Microsoft's VHD-compatible VPC format:

qemu-img convert -p -f vdi -O vpc "input.vdi" "output.vhd"

Inspect the result before attaching it:

qemu-img info "output.vhd"

Use the complete active snapshot image as the input when the VDI belongs to a differencing chain. QEMU's output is normally dynamically allocated; create a fixed image only with the tool and options supported by the installed QEMU version.

Using the built-in online converter

You can convert the file on 101convert.com for free without installing software. Uploading a disk image transfers its entire virtual disk, so do not use an online service for confidential or regulated data; retain the original until the output has been tested.

Compatibility and storage limitations

The conversion normally preserves partitions, filesystems, and guest data, but it does not convert the VM definition, snapshots, network settings, or other virtual hardware. Configure the destination VM with compatible firmware and storage hardware. Match the source boot mode, such as BIOS or UEFI; a Windows guest may require storage-driver detection or boot repair after moving to Hyper-V.

Converting a dynamically allocated VDI does not guarantee a smaller VHD. The output must hold the copied blocks, and a fixed VHD requires host storage roughly equal to its configured virtual capacity. Ensure the destination volume has sufficient free space.

Encrypted or inaccessible VDIs require the appropriate VirtualBox password or access credentials before they can be read. Never rename, move, or delete snapshot files during conversion. Test that the VHD boots and that important files open before removing the VDI.