Uninterruptible Power Supply Power Factor

For computer and Uninterruptible Power Supply(UPS) units, watt and volt-ampere ratings can vary significantly, although volt-ampere ratings are always equal to or greater than watt ratings. The ratio of watts to volt-amperes (VA) is called the "power factor" and is expressed as a number (such as -0.8) or a percentage (such as -80%). Power factor is most critical when selecting UPS specifications for your specific needs. Generally speaking, your UPS should have an output power capacity that is 20-25% greater than the total power drawn by any attached equipment.