Convert VMDK to VDI

To convert a disk file between formats, you perform a clone operation and specify the destination format.

$ VBoxManage clonehd myDisk.vmdk myDisk.vdi --format VDI

A lot of sites have you jump through hoops and pass through an intermediary bin format. However, that is simply not needed. Although VirtualBox runs fine with vmdk files, it is useful to have your images in vdi format so you can access all the features of the VBoxMange tool, such as modifyhd --compact.

If you don't mind using the internal command which is "...completely unsupported and will change in incompatible ways without warning." you can issue:

VBoxManage internalcommands converthd -srcformat VMDK -dstformat VDI <inputfile> <outputfile>