TV, cable and backup power calculators

UPS and Backup Power

These pages estimate backup power for routers, computers, NAS drives, TVs and small racks. One estimates runtime from the load and the battery, one adds up your equipment and gives the VA and watt rating to look for, and one works backward from a target runtime to a battery size. Real runtime is not linear and depends on the UPS, battery age and temperature, so treat the results as planning numbers and use the maker’s runtime chart for the model you choose.

Tools in this group

  • UPS Battery Calculator — Say how long you want to run a load, choose the bank voltage and the battery size, and see the capacity and battery count the formula gives.
  • UPS Runtime Calculator — Enter what is plugged in and the size of the battery, and the formula gives the runtime in hours and minutes, with each step written out.
  • UPS Sizing Calculator — List what you want to keep running, choose your headroom, and see the total watts and the VA rating the numbers point to.
  • VA to Watts Calculator — Type the VA (or watts) and the power factor, and the formula gives the other number, with a table at other power factors.