Sizing and run time calculators are based on Watt ratings. VA (Volt-Amp) ratings are also a common method for measuring power but provide less accurate results. On APC.COM, VA values are often shown for convienience and may be entered as input data. However, VA values are always translated into Watts. This translation is done using an approximation formula which assumes that low VA loads have a power factor of around 0.6 and high power loads have a power factor of nearly 1.0, which is representative of typical, (but not all) computing equipment. For highest precision, use Watt values where available.
The translator below shows how VA can be converted to Watts using the APC.COM formula: