How much backup time can a 500VA UPS (uninterruptible power supply) provide?

A 500VA uninterruptible power supply will have a built-in battery pack and the amount of runtime the UPS can provide when there is a mains power outage is dependent on the load connected. At 80% load a typical 500VA/500W UPS can provide 3-7 minutes of battery runtime. This can be extended by oversizing the uninterruptible power supply.