"Load" describes how much power (in watts) a device uses. The more devices, the higher the load. "Capacity" describes how much power (in watts) one or more Tripp Lite UPS systems can support during a blackout. The higher the capacity, the more devices they can support. The first step in the UPS selection process is to determine the required load and match it with one or more Tripp Lite UPS Systems that provide enough capacity to support the load. It is a balancing act - one should recommend a UPS system solution that has just the right amount of capacity for the job, no more and no less. If the UPS is “undersized” (will not provide enough capacity to support the load), it will automatically shut down once overloaded and cause downtime. If the UPS is "oversized“ (too much capacity to support the load), it will result in added electrical bills, since all UPSs will operate less efficiently the lower the connected load.