Appliance Monthly Cost Calculator
Turn any appliance’s wattage and daily use into the kilowatt-hours it burns and what it adds to your monthly electric bill.
How it works
kWh/month = watts ÷ 1000 × hours/day × days · Cost = kWh × rate
Every electric appliance is rated in watts, and electricity is billed in kilowatt-hours — one kilowatt (1000 watts) running for one hour. Divide the wattage by 1000 to get kilowatts, multiply by the hours you actually run it, and by how many days a month. The result times your per-kWh rate is the line the appliance adds to your bill, which is why a high-wattage device used briefly can cost less than a modest one left on all day.
Worked example
A 1500 W space heater run 3 hours a day for 30 days uses 1.5 × 3 × 30 = 135 kWh. At $0.17/kWh that is 135 × 0.17 = $22.95 a month, or about $0.77 each day it runs.
Frequently asked questions
Where do I find the wattage?
Check the nameplate label on the appliance, the spec sheet, or the manual. If only amps and volts are listed, multiply them: 12 A × 120 V = 1440 W. A plug-in power meter gives the most accurate real-world figure because many devices draw less than their maximum rating.
Does this include standby power?
No — it assumes the appliance draws its rated wattage only while running. Devices with standby modes (TVs, chargers, game consoles) also sip a few watts around the clock, which you can add as a second low-wattage entry run 24 hours a day.
What electricity rate should I use?
Use the total per-kWh rate from your bill, including delivery and supply charges, not just the energy portion. Rates commonly run $0.10–$0.30/kWh depending on region and time of use.
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This calculator is for educational purposes. Double-check important results before acting on them.