ebbillcalc

What size inverter for a fridge?

Keeping the fridge running through a cut, with two lights.

  • Typical appliance watts, change them in the calculator
  • Indian inverter sizes
  • Tubular or lithium
Inputs, results, working, link and sources, on your device.
Running load168 Wstarts at up to 468 W
Inverter650 VAneeds 263 VA
For 4 hours1 × 100 Ah tubularor 1 × 12.8 V 100 Ah lithium

Open this in the calculator

The load

Typical ratings. Check the plate on your own appliances; a BLDC fan uses about 30 W instead of 75 W.

ApplianceHow manyWatts eachTotal
Refrigerator motor1150 W150 W
LED bulb29 W18 W
Running load168 W

Battery for the backup you want

Tubular: 12 V batteries, the usual choice. Longer backup moves you to a 24 V inverter with two batteries. Lithium: LiFePO4 modules.

BackupTubular batteryInverter for thatLithium
2 hours1 × 100 Ah tubular650 VA, 12 V1 × 12.8 V 100 Ah lithium
4 hours1 × 100 Ah tubular650 VA, 12 V1 × 12.8 V 100 Ah lithium
6 hours1 × 120 Ah tubular650 VA, 12 V2 × 12.8 V 100 Ah lithium
8 hours1 × 150 Ah tubular650 VA, 12 V2 × 12.8 V 100 Ah lithium

What it adds to your bill

Power cuts a dayRechargingStandbyAdds to your bill
1 h7.9 units3.6 units11.5 units a month
2 h15.8 units3.6 units19.4 units a month
4 h31.5 units3.6 units35.1 units a month

Other homes and loads

1 BHK home2 BHK home3 BHK home4 BHK or independent house1 HP water pumpAir coolerWork from homeSmall shop1.5 ton AC

Questions

How is the inverter size worked out?

Running watts × 1.25 for a safety margin ÷ 0.8, the power factor Indian brands rate their inverters at. Then we pick the next standard size. Motors such as a fridge or pump also need starting surge, which we check against the inverter’s rating.

Why do the hours change the battery but not the inverter?

The inverter sets how much can run at once; the battery sets for how long. Longer backup needs more Ah, and past what one 12 V battery can give, a 24 V inverter with two batteries.

Will this raise my electricity bill?

Yes, a little. The battery is recharged from the grid after every cut, with some loss, and the inverter draws standby power all day. Each page shows the units a month; the calculator prices them at your state’s slabs.