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Electricity bill calculator

  

A flat price per unit, for a 30-day month. Real bills use slabs that get dearer as you use more, add fuel surcharge and duty, and a fixed charge. Take the average rate from your last bill for a closer figure.

Divide your last bill by the units on it.

Air conditioner (1.5 t)
Ceiling fan
Refrigerator
LED light
Geyser
TV

Estimated monthly bill

₹3,641

506 units a month at ₹7.00 per unit, plus the fixed charge.

Reading your electricity bill by appliance

An electricity unit is a kilowatt-hour: 1,000 watts used for one hour. To find what an appliance costs, multiply its watts by the hours you use it, divide by 1,000, and multiply by your rate. A 1,400 W air conditioner running 8 hours a day for 30 days uses 336 units. At ₹7 a unit that is about ₹2,350 a month on its own.

Compare that with the rest of the house. Three ceiling fans of 75 W running 12 hours add up to about 81 units, around ₹570. A fridge of 150 W that cycles through 8 hours of real running uses 36 units. Six LED bulbs at 10 W for 6 hours come to just 11 units. A geyser used half an hour a day, at 2,000 W, is 30 units.

So when the bill climbs in summer it is almost always the AC. Setting it at 24 to 26 °C instead of 18 can cut its use by a quarter or more, and servicing the filters helps too. Geysers are the other quiet cost, and a timer helps there.

Your bill rarely equals units times a flat rate, because of slabs and fixed charges. Take your last bill, divide the total by the units shown, and use that as the rate here.

Sources

What this calculator does not account for

  • Slab rates, fuel adjustment charges and electricity duty.
  • Appliances that draw less than their rated watts.
  • Seasonal use that changes the bill from month to month.

How this is calculated

Formula: Units and cost

units (kWh) =watts × hours × number × days ÷ 1000; bill =units × rate + fixed charge

What the symbols mean

  • wattsPower rating printed on the appliance.
  • hoursHow long it runs each day.
  • rateYour average price per unit, in rupees.

Good to know

  • One unit on your bill is one kilowatt-hour: a 1,000 W heater for one hour.
  • Compare with fuel for your car using the fuel cost calculator.

Read the full methodologyFound an error? Contact us

Worked examples

Each example is worked out by the same code as the calculator above.

The 1.5-tonne AC

1,400 W × 8 h × 30 days ÷ 1000 = 336 units. At ₹7 a unit, ₹2,352 a month.

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Questions

How many units does an AC use?

A 1.5-tonne AC is rated about 1,400 W. Running 8 hours a day for a month that is 336 units; with the compressor cycling off it may be closer to 250.

How do I find the wattage of an appliance?

Look at the label on the back, or the manual. If it only lists volts and amps, multiply them.

Why does my real bill not match?

Slab rates make later units dearer, and bills add fixed charges and duty. Use the average of your last few bills as the rate.

What are the biggest energy users at home?

Air conditioners, geysers and water heaters, then refrigerators, because they run all day. Fans and LED lights barely register.