VDI vs VHD vs VMDK and How to Convert Virtual Disks

VDI, VHD and VMDK are three widely used virtual disk formats, each built for a different virtualization ecosystem. All three act as virtual hard drives holding operating systems, applications and data, and each one is tuned for its own platform and brings its own capabilities.

Updated September 2026 · Mr.PlanB

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VDI is the native format for VirtualBox. It handles fixed and dynamically allocated disks, snapshots and sparse allocation. It travels between host operating systems, though it is happiest inside VirtualBox, and using it elsewhere usually means converting it first.

VHD belongs to the Microsoft virtualization platforms. It supports fixed, dynamic and differencing disks, works with the Windows management tools and lets several operating systems live on one host. It stops at 2 TB, and it misses some of the storage features the newer formats have.

VMDK comes from VMware and is now supported across most other hypervisors too. It does snapshots, sparse allocation, RAID protection inside SAN environments, incremental backup, and disks as large as 62 TB in current implementations.

Converting between the formats works with the built-in tools: VirtualBox's Virtual Media Manager, PowerShell modules or command-line utilities such as VBoxManage. In an enterprise migration, dedicated tools handle the same job without anyone touching the disks by hand.

Which format is “best” comes down to the target hypervisor, what you need to stay compatible with, how much capacity you want and the performance you expect.

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