Buying a UPS or AVR hers the guide for you,

To convert W to VA, the equation is


or


Where PF is power factor of the devices, power factor varies depending on devices such as computer power supply unit, usually computer power supplies have PF over 0.9 or 90% but some devices are as low as 0.3 or 30%, so the industries came up with a standard PF which is actually a average conservative power factor which is 0.6 or 60%, so basically when you purchase a UPS/AVR the do the following for recommended rating for UPS/AVR.



if you tight on budget yet you want a UPS/AVR for a computer then do following



hope this helps, more details on link below

http://www.powerstream.com/VA-Watts.htm

This post has been edited by Kizarh: Sep 16 2011, 01:00 AM