A method, system, and/or computer program product provide a custom virtual appliance. One or more processors generate a description file of a custom virtual appliance based on a user requirement. The processor(s) acquire configuration metadata of the custom virtual appliance from the description file. The processor(s) create a list of candidate virtual appliances based on the configuration metadata. The processor(s) acquire a disk size of the custom virtual appliance based on configuration metadata. The processor(s), for a specific virtual appliance in the list: acquire a disk size of the specific virtual appliance; and determine, based on the disk size conversion information, whether the specific virtual appliance is required to convert a disk size of the custom virtual appliance. In response to determining that a candidate virtual appliance from the list is required to convert the virtual disk, the processor(s) construct the candidate virtual appliance as the custom virtual appliance.