Home Energy Cost Calculator
Find what an appliance costs to run per month and year.
Results update as you type.
How it works
Every appliance quietly adds to your electricity bill, and this home energy cost calculator shows exactly how much any single device costs to run. Enter its power draw in watts, how many hours a day you use it, and your electricity rate, and it returns the monthly kilowatt-hours consumed, the monthly cost, and the yearly total. The calculation rests on how utilities bill you: not by watts but by kilowatt-hours, the energy used when a 1,000-watt device runs for an hour. A high-wattage appliance used briefly can cost less than a modest one left on all day, which is why both power and hours matter. Converting to a monthly and annual figure makes the running cost tangible rather than abstract. This clarity helps you spot the expensive habits worth changing. An old refrigerator, a space heater, or a gaming PC left idle can quietly consume more than you expect, while efficient LED bulbs cost pennies. Households budgeting utilities, renters comparing appliances, and anyone chasing lower bills use a home energy cost calculator to decide what to unplug, replace, or run less. Pair the figures with an appliance's efficiency label and you can prioritise upgrades that pay for themselves through the electricity they save each year.
monthly kWh = watts × hours/day × 30 ÷ 1000 · cost = kWh × rate
Electricity is billed by the kilowatt-hour, so an appliance's monthly energy equals its power in watts multiplied by daily running hours and by thirty days, then divided by 1,000 to convert watt-hours into kilowatt-hours. Multiplying that energy by your rate per kilowatt-hour gives the monthly cost, and multiplying the monthly cost by twelve produces the annual figure, showing the full-year expense of leaving a device running.
Source:Standard energy calculation
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter appliance power, hours used per day and electricity rate.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Monthly cost updates instantly as you type — no button to press.
Frequently asked questions
Where do I find an appliance's wattage?
Most appliances list their power draw on a label near the plug, on the back or base of the unit, or in the manual, usually marked in watts or as volts and amps that multiply to watts. Energy guides and manufacturer spec sheets also list it. For devices that cycle on and off, like refrigerators, use the average running wattage rather than the peak startup figure for a realistic estimate.
Does this account for appliances that cycle on and off?
Not automatically. The calculator assumes the device draws its stated wattage for the hours you enter. For something like a fridge or air conditioner that runs intermittently, estimate the equivalent full-power hours instead — a fridge rated at 150 watts might only run its compressor eight hours a day even though it is plugged in continuously. Entering that effective run time gives a far more accurate monthly cost.
Why is my bill higher than the sum of individual appliances?
This tool costs one appliance at a time, but your bill combines every device plus heating, cooling, standby power, and possible tiered or time-of-use rates. Many gadgets draw phantom power even when switched off, and peak-period pricing can exceed the flat rate you entered. Add up several appliances here and compare against your bill to find the gap, which often reveals always-on loads you had overlooked.
How can I use this to cut my electricity costs?
Run the numbers for your biggest or longest-running devices first, since they dominate the bill. Compare the annual cost of an old appliance against an efficient replacement to see the payback on an upgrade. Reducing daily hours, switching to LED lighting, and eliminating standby draw all lower the figures shown here. Targeting the few high-cost items usually saves far more than fussing over minor low-wattage gadgets.
Does a 30-day month affect accuracy?
The calculator uses a flat 30-day month for consistency, so months with 28 or 31 days differ slightly, and the annual figure is the monthly cost times twelve rather than a precise 365-day sum. These small rounding choices keep the math simple and the difference is negligible for budgeting. If you need exact billing-period figures, scale the daily cost — watts times hours times rate divided by 1,000 — by the actual number of days.