Tripp Lite UPS system capacities are listed in both watts and VA. Both capacities are useful, but for the purposes of selecting a UPS System, watts must be used. VA considers the electrical resistance that occurs when a device interacts with the electrical circuit it's plugged into. So, in very simple terms, as the device is pulling power, the electrical circuit is resisting and pulling back. Since VA takes this resistance into account, a UPS system's VA rating is always equal to or higher than its wattage rating. Why should one use watts instead of VA? Watts is a truer measure of the power that a device will draw from the UPS system's receptacles (without overloading it). VA is used for determining the power that a UPS system will draw from the wall outlet-more important when considering electrical circuit design, but not useful when selecting a UPS system. Incidentally, devices with larger capacities will be listed in increments of 1,000 VA (kVA).