What This Calculator Estimates
This calculator estimates how much it costs to run an appliance based on its wattage, how many hours per day you use it, and your electricity rate. It's useful for comparing appliances or spotting which devices are driving up your power bill.
Formula / Method Used
Daily kWh = (Watts × Hours Used) ÷ 1000. Monthly cost = Daily kWh × Rate × 30. Annual cost = Monthly cost × 12.
Worked Example
A 1,500-watt appliance run 1 hour per day at $0.15/kWh uses 1.5 kWh daily, costing about $6.75 per month and $81 per year.
How to Interpret the Result
Higher wattage and longer daily use both increase cost directly. Use the annual figure to compare appliances side by side, or to judge whether a more efficient replacement would pay for itself over time.
Common Mistakes
- Using rated wattage when actual draw is lower (check the nameplate for "running" vs "peak" watts).
- Forgetting to include standby power draw for always-on devices.
- Mixing up watts and kilowatts.
- Using an outdated electricity rate from an old bill.
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Frequently Asked Questions
What does this appliance cost calculator estimate?
It estimates the monthly and annual electricity cost of running an appliance based on its wattage, daily usage hours, and your electricity rate.
Where do I find my appliance's wattage?
Check the appliance label, spec sheet, or manual for its wattage rating, often listed in watts (W) or kilowatts (kW).
Where do I find my electricity rate?
Your electricity rate per kWh is listed on your utility bill, usually shown as cents or dollars per kilowatt-hour.
Does this include standby power usage?
No. This estimates active-use cost only and does not account for standby or phantom power draw.
When should I recalculate?
Recalculate if usage hours change, you switch appliances, or your electricity rate changes.
Last updated: July 2026