Electricity Cost Calculator
Adjust the inputs below. Results update as you type.
How it works
Cost = watts × hours / 1000 × price per kWh. US average electricity rate is about $0.13/kWh but varies from $0.09 (Louisiana) to $0.30+ (Hawaii). A 60W bulb running 8 hours/day costs about $1.87/month. Standby power (phantom load) for electronics adds 5–10% to typical household bills. Smart plugs with energy monitoring give exact readings.
Input guidance
- Confirm date/time/unit settings before comparing outputs.
- If a task has optional fields, run both with and without them to understand impact.
- Save scenario variants when making practical decisions.
The formula
Cost = (watts ÷ 1000) × hours used × price per kWh. Multiply by days for monthly or yearly totals.
Worked example
A 60-watt bulb on for 5 hours a day costs (60 ÷ 1000) × 5 × $0.15 = $0.045/day, about $16/year.
More examples to test
- Quick-pass example: run default assumptions for a first estimate.
- Refined example: update one assumption at a time to isolate impact.
How to interpret results
Use outputs as operational estimates and pair them with local constraints, business rules, or provider requirements.
When this can be inaccurate
Utilities can miss local policy details, special-case rules, and environment-specific constraints.
Change history
- June 2026: Quality-reviewed for publication with formula checks and explanatory copy updates.
Site-wide corrections also appear on the corrections log.
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Frequently asked questions
How do I calculate an appliance's electricity cost?+
Convert its wattage to kilowatts, multiply by hours of use to get kWh, then multiply by your electricity rate per kWh.
Where do I find the wattage?+
On the device label or nameplate. For variable devices, use an average; some appliances list annual kWh estimates instead.
Does standby power add up?+
Yes. Devices left in standby draw small amounts continuously, which can total a noticeable share of a home's annual bill.
Why are outputs slightly different from another tool?+
Different tools can use different rounding rules, default assumptions, and treatment of edge cases.
How can I improve estimate reliability?+
Use verified inputs from real records and re-run calculations after major assumption changes.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.
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