Inverter & Battery Calculator
Size a home backup system to your needs: enter the load you want to run and the backup hours, and get the inverter VA rating and the battery capacity (Ah). Size to your essential loads, not the whole house. This is an indicative planning aid — confirm the final sizing with a licensed electrician and battery supplier.
12 V uses one battery; 24 V / 48 V use 2 / 4 in series for larger systems.
Sized so the inverter covers the load you run at once (watts ÷ 0.8), and the battery carries it for 3 hours (watts × hours ÷ (voltage × 0.8)). Add margin and avoid habitual deep discharge to protect battery life.
Indicative only. This uses a typical power factor and a combined efficiency/usable-capacity allowance; real backup time also depends on battery type, age, temperature, depth of discharge and load pattern. It does not size for heavy motor-starting loads (ACs, pumps) — those need professional sizing and often a generator. Confirm the inverter, battery and the changeover switch with a licensed electrician and battery supplier.
Related Guides — Deep-dive reading
Inverters & Batteries: How They Work & How to Size Them
The silent workhorse of Indian home backup — how an inverter turns battery power into mains, what the VA rating means, why sine-wave matters, how to size the inverter to your load and the battery to your backup hours, and how to keep the system healthy.
Electrical & WiringHome Generators: Portable, Standby, Sizing & When You Need One
When a battery isn't enough — how a generator produces power for heavy loads and long outages, the difference between a portable set and a fixed standby DG, how they are sized, the fuel, noise and emission realities, and whether a home actually needs one.
Electrical & WiringHome Backup Power: Inverter, Generator or UPS?
How to keep the lights on when the grid goes down — the three backup options compared (inverter-battery, generator, UPS), how to decide which your home needs, the idea of 'essential loads' that makes backup affordable, and why a proper changeover switch is non-negotiable.
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