Appliance electricity cost:
watts ÷ 1,000 × hours × rate

How to work out what an appliance costs

An appliance costs its power in kilowatts, times the hours it runs, times your rate per unit. At ₹8 per kWh, a 1,000 W iron used for half an hour costs 1 × 0.5 × 8 = ₹4.

The Calcylator tool takes power in W, usage from 0 to 24 hours in quarter-hour steps (the slider starts at 4), and the rate in rupees per kWh, and returns the estimated cost in INR.

Cost table for common appliances

The wattages below are assumed round figures for illustration. Check the label on your own appliance, because ratings vary with the brand and model. The rate is ₹8 per kWh and the hours are a plausible daily use.

The pattern is clear: high wattage and long hours together matter. A bulb is cheap even when left on all evening, while one air conditioner can outweigh everything else in the house.

What actually moves the bill

• Air conditioners and heaters: high power and long hours, so small changes in hours save the most.
• Geysers: short use but high watts, so trimming five minutes a day adds up over a month.
• Always-on devices: a fridge draws power all day, although its compressor does not run at full rating non-stop, so the table value is an upper-end guide.
• Small items such as bulbs and chargers: cheap per hour, so low priority.

Habits matter too. A 100 W television that runs 10 hours a day costs 0.1 × 10 × 8 = ₹8 daily, against ₹3.20 for 4 hours. The extra six hours add ₹4.80 a day, or ₹144 over 30 days, even though the set is not changing at all.

Finding your rate and hours

Look at your bill for the price per unit. Many bills use slabs, with a higher rate as total monthly usage rises, so the rate you pay on the extra units can be above your average. Enter the rate that applies to your top slab if you want to see the marginal cost of an extra appliance.

For hours, estimate average daily use. A fan used 8 hours is 8, an iron used 30 minutes is 0.5, and a bulb used 15 minutes is 0.25, which the slider can enter directly.

Common mistakes

• Forgetting to divide watts by 1,000, which makes the cost 1,000 times too high.
• Using a monthly bill average as the rate when slabs apply.
• Trusting the rated watts of appliances that cycle on and off, such as a fridge or an air conditioner with a thermostat.
• Ignoring standby power from televisions and chargers left plugged in.
• Treating the result as exact. It is an estimate based on the numbers you enter.