About this Device Power Cost
Electricity bills are often a mystery. By breaking down the cost of individual appliances, you can identify where your money is going. This tool converts Wattage and Usage Hours into Kilowatt-hours (kWh) and multiplies by your utility rate to find the exact cost.
Who this calculator is for
- Homeowners, renters, and office managers estimating the running cost of a device.
- PC builders and lab teams comparing the energy cost of always-on equipment.
- Anyone deciding whether a more efficient appliance is worth the upgrade.
When to use it
- Use it to estimate the monthly and yearly cost of a PC, heater, server, or appliance.
- Use it when comparing the energy impact of two devices with different wattage ratings.
- Use it before budgeting for 24/7 equipment like networking gear or home labs.
How to use this calculator
- Find the Wattage of your device (check the sticker on the back or power brick).
- Estimate how many Hours per Day it runs.
- Enter your Electricity Rate (Cost per kWh found on your utility bill).
- See the daily, monthly, and yearly cost.
Key assumptions
- Wattage is treated as a steady average draw over the entered daily runtime.
- Monthly cost is estimated using a 30-day month and yearly cost uses 365 days.
- Negative wattage, hours, or utility-rate values are invalid.
Dataset sources
- Effective date
- 2024
- Last reviewed
- 2026-05-05
State and national average retail rates are planning references, not a utility tariff or time-of-use schedule.
Public U.S. Energy Information Administration data.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
Inputs explained
Device Wattage
The power consumption of the device. For variable devices (like a fridge), use the average running watts.
Hours Used
Average active runtime per day.
Cost per kWh
The rate your utility company charges. The US average is roughly $0.15/kWh, but it varies from $0.10 to $0.30+.
Understanding your results
Example scenarios
Space Heater
1500 Watts. 4 Hours/day. Rate $0.15. Cost = $27.00/month.
Gaming PC
400 Watts. 6 Hours/day. Rate $0.15. Cost = $10.80/month.
LED Bulb
10 Watts. 8 Hours/day. Rate $0.15. Cost = $0.36/month.
Key Features
- Annual Cost Projection
- kWh Consumption
- Adjustable Rates
Tips & Best Practices
- Devices in 'Standby' still consume power (Phantom Load). A TV might use 50W while off.
- Heating and cooling appliances (AC, Heater, Dryer) are usually the most expensive to run.
- Check if your utility offers 'Time of Use' rates, where electricity is cheaper at night.
Glossary of Terms
- kWh
- Kilowatt-hour. A unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour.
- Watt
- A unit of power. 1000 Watts = 1 Kilowatt.