Free online QCOW to VHD converter

Source format: qcow

QCOW is an early QEMU Copy-On-Write virtual disk image format used by the QEMU emulator and related virtualization tools. It stores a virtual hard drive in a file and supports features such as copy-on-write, snapshots, and sparse allocation. QCOW is mainly found in older QEMU-based environments and legacy virtual machine setups.

Typical use cases include archiving virtual disks, moving old VM images between QEMU systems, and working with older Linux virtualization workflows. In practice, many users now encounter QCOW2 more often than QCOW, but the conversion process is similar.

Target format: vhd

VHD is the Virtual Hard Disk format originally associated with Microsoft virtualization products such as Virtual PC and older versions of Hyper-V. It represents a virtual machine disk as a single file and is widely recognized by many virtualization platforms and disk utilities.

Advantages of VHD include broad compatibility with Microsoft ecosystems, support in many hypervisors, and straightforward portability. It is commonly used when migrating virtual machines to environments that expect VHD images or when exchanging disks with older Windows-based virtualization systems.

How to perform the conversion

The most reliable method is to use qemu-img, a command-line tool included with QEMU. It can read QCOW images and write VHD output directly.

1. Install QEMU tools if they are not already available on your system.
2. Open a terminal or command prompt.
3. Run a conversion command such as qemu-img convert -f qcow -O vpc source.qcow target.vhd.
4. If your file is actually QCOW2, use qemu-img convert -f qcow2 -O vpc source.qcow2 target.vhd.
5. Verify the result by checking the new file in your virtualization software or with qemu-img info target.vhd.

In this command, -f qcow tells QEMU the source format, and -O vpc selects the VHD family format used by QEMU for Microsoft-compatible virtual disks. If you prefer a graphical workflow, some desktop virtualization tools can import one disk format and export another, but qemu-img is usually the most direct and dependable option.

You can also convert the file on 101convert.com for free, without installing any software.

Notes on quality, compatibility, or limitations

QCOW to VHD conversion is usually lossless at the data level, but some QCOW-specific features do not carry over. For example, snapshots, backing-file chains, and certain metadata are not preserved in a plain VHD file. If the source image depends on a backing file, make sure the chain is fully merged before conversion.

Be aware that VHD has format limitations compared with newer disk formats. It is less flexible than VHDX and may be less suitable for very large disks or advanced features. If your target platform supports it, consider whether VHDX would be a better long-term choice.

Finally, confirm that the converted disk boots correctly in the destination hypervisor. Differences in virtual hardware, boot mode, or partition style can affect startup even when the disk conversion itself succeeds.