UPS battery backup time calculator app is designed to give you the calculated estimated time before the battery exhaustion. Type your total battery amps (written on battery like 55, 100, 180, 200 amp etc) in the app and type total load connected live (e.g 100 watts , 300 watts), based on your appliances connected to ups. 1 fan load is 100 watts while 2 fan and 2 light bulbs running load is 250 watts. On entering these details you can get your total run time for battery or backup time.
Please note that results will be based on fresh battery, if your battery is old its performance may effect up to 50 - 80% in values.