Inverter & UPS Runtime Calculator

Calculate battery backup for Home, Office, and Shops in India.

V
12V (1 battery), 24V (2 batteries)
Ah
Check battery label (e.g., 150Ah)
%
80% is standard for India
W
Don't know your watts? Check the chart below.

Common Indian Appliance Power Ratings

Use this chart to estimate your total load (Watts) for the calculator.

Appliance Avg. Watts
Ceiling Fan (Standard)75W
Ceiling Fan (BLDC)35W
LED Tubelight / Bulb20W / 9W
Wi-Fi Router15W
Laptop Charging65W
LED TV (43-55 inch)80W - 120W
Desktop PC (Standard)250W
Gaming PC450W+
Mixer Grinder500W - 750W

How is Inverter Backup Time Calculated?

The backup time of an inverter or UPS is determined by the battery capacity (measured in Ampere-hours or Ah) and the total load connected to it. The formula used is:

Backup Time = (Battery Volt x Battery Ah x Efficiency) / Load Watts

For example, a 150Ah Tubular Battery (12V) running a Ceiling Fan and TV (approx 150 Watts) with 80% inverter efficiency will last roughly 9.6 hours.

Why is my backup less than calculated?

In India, battery performance degrades over time. Old batteries (3+ years), sulphation, and low water levels in tubular batteries can reduce backup by 20-30%. Always maintain distilled water levels for maximum runtime.