Most of the time i prefer using  VMware workstation , good thing about VMware virtual machine is it works perfect in vmware products for any platform . but when i started using virtualbox then i tried to import directly vmware virtual machine which is not possible .

ovf tool come very handy that’s export virtual machine from vmware vm to ovf ( open virtualization format ) then i can import that virtual machine in virtual box

if you want to export virtual machines from vmware workstation its really easy

• Select the virtual machine and select File > Export to OVF.
• Type a name for the OVF file and specify a directory in which to save it.
• Click Save to start the OVF export process.
• The export process can take several minutes. A status bar indicates the progress of the export process.

if you are using vmware fusion then you can use ovf tool to export virtual machine

ovf tool is comes in bundle with vmware fusion so you dont have to do anything extra

Location :  /Applications/VMware Fusion.app/Contents/Library/VMware OVF Tool

procedure :

1. make sure virtual machine is not encrypted and make sure vm is  currently switch off 
2. open terminal
3. cd to  “/Applications/VMware Fusion.app/Contents/Library/VMware OVF Tool”

pass -h to see help docs

Usage: ovftool [options]  []
$  ./ovftool --acceptAllEulas ~/Documents/Virtual\ Machines.localized/Ubuntu\ 64-bit.vmwarevm/Ubuntu\ 64-bit.vmx ~/Desktop/ubuntu.ovf


    
      
  
          
          
          
        
    
    
  

it will take some time to export then you can easily import that vm easily in virtual box