Appliance energy cost calculator
Estimate the energy use (kWh) and cost of a household appliance from its wattage, daily hours, days and unit count, with an editable tariff. Amounts are rounded to whole cents and typical wattages are included as reference values.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Appliance parameters
Wattages and tariffs are reference values — real devices and regions differ a lot. Amounts are computed in whole cents and rounded only once, at the end.
Estimate
Fill in the parameters and press “Calculate” to get the energy and cost estimate.
What this tool does
- Find out what “the air conditioner on all night” actually costs: 1100 W, 8 hours a day, 30 days at 0.6 per kWh gives 264 kWh and 158.40.
- Compare two appliances at the same tariff — is the space heater or the air conditioner the expensive one?
- Before buying: plug the rated wattage of a candidate model in and see its yearly cost at your usage pattern.
- Build a home energy list: work out which appliances dominate, then decide what to replace first.
Example
Input
2000 W, 3 hours a day, 30 days, 1 unit, tariff 0.6 per kWh
Output
180 kWh used, cost 108.00; 6 kWh per day, 180 kWh per month, 2190 kWh per year
At 0.5 per kWh the cost drops to 90.00; with 2 units the energy doubles to 360 kWh and the cost to 216.00.
Frequently asked questions
How is the energy figure derived?
kWh = watts × hours per day × days × units ÷ 1000, and cost = kWh × tariff. That is just the definition of power; no empirical factors are involved. Real consumption drifts from the estimate because of load variation, standby draw and inverter behaviour.
Why are amounts computed in cents?
Because multiplying 0.1 kWh by 0.567 in floating point accumulates error. The tool converts the tariff to whole cents per kWh first and rounds once at the very end, so 0.05 never displays as 0.04.
Are the preset wattages accurate?
They are typical reference values. Two 12000 BTU air conditioners can differ by more than a factor of two depending on inverter technology and efficiency class. Use the nameplate rating when accuracy matters.
Why does it differ from my bill?
A bill also carries tiered or time-of-use pricing, fixed charges and levies, and appliances rarely run at full power continuously. This tool gives a linear estimate from the numbers you enter — most useful for relative comparisons.
Is anything uploaded?
No. Everything is computed locally in the browser, the page makes no requests, and a refresh clears it.
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