Electricity Bill Calculator

Estimate what an appliance costs to run per month and year from its wattage, usage hours, and your energy rate.

Power (Watts)

Find the wattage on the appliance label or nameplate.

Hours Used per Day

Days Used per Month

Electricity Rate ($/kWh)

Your price per kilowatt-hour, shown on your utility bill.

Results update as you type.

Monthly Cost

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Monthly Energy (kWh)—

Annual Cost—

How it works

An electricity bill calculator estimates what a single appliance or device costs to run by combining its power draw with how long you use it and the price your utility charges per kilowatt-hour. Electricity is billed by the energy consumed, not by the device itself, so a modest gadget left on all day can quietly cost more than a powerful one used briefly. Seeing the monthly and yearly figure turns an abstract wattage rating into real dollars you can act on. The calculation rests on the kilowatt-hour, the unit utilities meter and bill. Multiply an appliance's wattage by the hours it runs each day and the days it runs each month, then divide by one thousand to convert watt-hours into kilowatt-hours. Multiplying that energy by your local rate gives the monthly cost, and multiplying by twelve projects the annual total. Homeowners auditing a space heater, renters comparing an old refrigerator to a newer model, and anyone hunting down phantom loads use this to decide whether an upgrade or a habit change is worth it. Because rates vary widely by region and season, entering your own per-kilowatt-hour price makes the estimate specific to your household rather than a national average.

Formula

kWh = Watts × Hours/day × Days/month ÷ 1000; Monthly Cost = kWh × Rate; Annual Cost = Monthly Cost × 12

Wattage measures power — the rate at which energy is drawn — while a bill charges for energy, which is power multiplied by time. Multiplying watts by the daily hours and monthly days gives watt-hours, and dividing by one thousand converts them into kilowatt-hours, the unit your meter records. Multiplying that energy by the per-kilowatt-hour rate lands on the monthly cost, and scaling by twelve extends it across a full year of steady use.

Source:Standard cost calculation

We review all our tools from time to time to ensure accuracy.

Worked example

Power (Watts):1000Hours Used per Day:5Days Used per Month:30Electricity Rate ($/kWh):0.15

A 1,000-watt heater run 5 hours a day for 30 days uses 1,000 × 5 × 30 ÷ 1,000 = 150 kWh. At $0.15 per kWh, that is 150 × $0.15 = $22.50 per month, or roughly $270 across a full year.

How to use this calculator

1
Enter your values
Enter power (watts), hours used per day, days used per month and electricity rate ($/kwh).
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?

Look for a rating label on the back or underside of the device, near the power cord, or on the nameplate. It lists watts (W) directly, or volts and amps that you multiply together to get watts. Motors and heaters often show a peak figure higher than typical draw. If only amps are shown, multiply by your outlet voltage — 120 volts in the United States — to estimate the wattage.

What electricity rate should I enter?

Use the price per kilowatt-hour from your most recent utility statement, usually printed near the usage summary. In the United States residential rates commonly fall between roughly 10 and 30 cents per kilowatt-hour, but they vary sharply by state, provider, and season. If your plan has tiered or time-of-use pricing, enter the rate for the tier or hours the appliance actually runs to get the most accurate estimate.

Does a device use power when it is switched off?

Often yes. Many electronics draw standby or phantom power to keep remotes, clocks, and network features alive, typically one to a few watts each. Individually small, these loads add up across a whole home and run every hour of the year. To include them, enter the standby wattage with 24 hours a day. A smart power strip or unplugging idle chargers eliminates most of this waste.

Why does my estimate differ from my actual bill?

This calculator covers one appliance at a steady wattage, while your bill totals every device in the home. Real draw also fluctuates: refrigerators and air conditioners cycle on and off, and heaters modulate with the thermostat. Bills add fixed service charges, taxes, and delivery fees on top of energy. Treat the result as a per-device estimate for comparison and budgeting, not a precise prediction of the whole household total.

How can I cut an appliance's running cost?

Reduce any of the three factors: wattage, hours, or rate. Replace incandescent bulbs and old motors with efficient LED or ENERGY STAR models to lower wattage. Cut runtime with timers, thermostats, and simply switching things off when idle. Shift heavy loads like laundry or dishwashing to off-peak hours if your plan charges less then. Small changes to a device that runs many hours daily produce the biggest yearly savings.