1000 W for 3 h/day
- Energy
- 90 kWh
- Days
- 30
- Rate
- $0.16 per kWh
Electricity Calculator
Estimate appliance electricity use from watts, hours per day, days, and price per kWh, then see kWh and cost examples.
Inputs explainedResult checksExample valuesRuns in your browser
Formula steps
- Convert watts to kilowatts by dividing by 1,000.
- Multiply by hours per day and number of days to get kWh.
- Multiply kWh by your electricity rate.
Examples
Recent answers
Recent electricity estimates will appear here.
Electricity cost math stays local and uses the rate you enter.
Inputs and recent answers stay in this browser tab and are not sent to a server.
How to use the Electricity Calculator
- Enter watts, hours per day, days, and your rate per kWh.
- Press Estimate electricity cost to see kWh and cost.
- Use your real utility rate when you want a closer estimate.
- Remember bills can include taxes, fees, tiered rates, and variable device power.
What people use it for
Estimate appliance energy use.
Compare a heater, AC, computer, or light over time.
Turn watts and usage time into kWh.
Multiply kWh by your local rate.
Check whether a device is worth measuring with a plug-in power meter.
Compare monthly and yearly energy-cost scenarios.
Quick examples
Space heater
1,500 W, 4 h/day, 30 days, $0.16/kWh180 kWh, about $28.80
LED bulb
10 W, 5 h/day, 365 days, $0.16/kWh18.25 kWh, about $2.92
Gaming PC
450 W, 3 h/day, 30 days, $0.18/kWh40.5 kWh, about $7.29
Window AC
900 W, 8 h/day, 30 days, $0.16/kWh216 kWh, about $34.56
Need the guide or a nearby tool?
Need a slower walkthrough, a related calculator, or the full library? These links keep you close to the task you started.
- How to use the Electricity CalculatorSee slower examples, input meanings, formula notes, result limits, and mistakes to avoid.
- Everyday ToolsBrowse related calculators and utilities in the same category.
- Electrical Calculator HubCompare this with the nearby tools and checks in the same job path.
- Calculator and utility guidesFind more guides that use real tool inputs and example numbers.
- All free toolsSearch every live tool, converter, calculator, AI helper, and browser utility.
Frequently asked questions
Plain-language answers about when to use the tool, what it does with your inputs, what to double-check, and how privacy works.
When should I use the Electricity Calculator?
Use it when your task matches one of these common needs: Estimate appliance energy use. Compare a heater, AC, computer, or light over time. It works best when you already know the measurements, amounts, units, or options the page asks for.
What is the Electricity Calculator doing with my inputs?
In plain language: The calculator divides watts by 1,000 to get kilowatts, then uses kWh = (watts / 1,000) x hours per day x days. Estimated cost = kWh x rate per kWh. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.
What do the main Electricity Calculator inputs mean?
Watts: the device power draw from a label, meter, or reasonable estimate. One kilowatt is 1,000 watts. Hours per day: how long the device actually runs on an average day, not always how long it is plugged in. Days: how many days are in the estimate window, such as 30 for a rough month or 365 for a year. Rate per kWh: your electricity price for one kilowatt-hour before taxes, fixed charges, or other bill fees.
How should I read the Electricity Calculator answer?
Read the headline answer, then check the smaller lines beside it. For everyday tools, those lines usually show the distance, time, cost, units, or setting that made the answer change.
What should I double-check before trusting the answer?
This is an appliance-level estimate from the numbers you enter. Real bills can include taxes, fees, tiered rates, demand charges, standby use, cycling devices, seasonal changes, and variable power draw. Also check the unit, scale, mode, and result limit because small input changes can change the answer.
What is a kilowatt-hour?
A kilowatt-hour is energy use. Running a 1,000 watt device for 1 hour uses 1 kWh. Running a 100 watt device for 10 hours also uses 1 kWh.
How do I estimate monthly electricity cost?
Use 30 or 31 days, enter the device watts, estimate average hours per day, and enter your rate per kWh. For example, 1,500 W for 4 hours a day over 30 days is 180 kWh, which costs $28.80 at $0.16/kWh.
Why can my real bill be different from this estimate?
The calculator only estimates one device from watts, time, and rate. Your full bill can include fixed fees, taxes, tiered pricing, demand charges, fuel adjustments, standby loads, and other devices.
What if the appliance cycles on and off?
Use average watts or average running time when you have it. Refrigerators, air conditioners, heaters, pumps, and dehumidifiers can cycle, so nameplate watts can overstate or understate real energy use.
Is kW the same as kWh?
No. kW is power, or how fast energy is being used. kWh is energy over time, which is why bills usually charge by kilowatt-hour.
Does standby power count?
Yes, if the device uses power while idle and you include that wattage and time. A plug-in power meter can help when the standby draw is small but runs all day.
Does the site save what I enter?
No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.