Wattage Calculator
Power draw from volts and amps, and what running it costs.
What is Wattage?
Two questions sit behind "what does this cost to run": how much power the thing draws, and how much energy that is over time. P = V × I answers the first; the second is power in kilowatts times hours, multiplied by the price per kilowatt-hour on your bill. Appliance presets fill the watts from a nameplate for the cases where volts and amps are not printed separately.
How it works
Watts come from the voltage and current if both are given, otherwise from the wattage field. The kilowatt-hours are computed first — watts ÷ 1000 × hours × days — and the cost is that figure times the tariff, in that order deliberately, because multiplying watts by a price is the classic factor-of-1000 error. The result reports energy per day, energy over the period, the daily and total cost, and the annualised cost at the same usage, plus the implied load resistance.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.