Short for Volt Amperes, this refers to the load bearing capability of the UPS. The higher the VA rating, the greater the supported load. The supported load refers to the total power requirements of the PC. Since electrically Watts = VA, the total wattage of the components of the system is a good indicator of the suggested VA rating of the UPS that will be needed. It is recommended to leave some headroom and settle for an UPS marked at least 20% higher.