Quick answer
Electricity Cost Calculator quick answer
Formula: Energy = watts ÷ 1,000 × runtime × duty cycle × quantity. Cost = kWh × electricity rate.
Example: A 1,500 W heater used 5 hours per day at $0.18/kWh and a 100% duty cycle uses 7.5 kWh per day and costs about $1.35 per day.
Reviewed September 1, 2026 · Methodology
Worked example
A 1,500 W heater used 5 hours per day at $0.18/kWh and a 100% duty cycle uses 7.5 kWh per day and costs about $1.35 per day.
What to do with the result
Use the rate from your actual utility bill and realistic average power/runtime. Nameplate watts can overstate devices that cycle on and off.
Public API & AI agent access
Yes — this calculator is callable programmatically. Use GET /api/v1/electricity-cost, the public calculator API, or tannerd.net's MCP, A2A and WebMCP agent interfaces. Results include a human-facing citation URL.
Frequently asked questions
How do I calculate appliance electricity cost?
Convert watts to kilowatts, multiply by runtime to get kWh, then multiply by your electricity rate.
What is duty cycle?
The percentage of the scheduled runtime that the device is actually drawing the entered power. Use 100% for a constant load.
Formula provenance
API identifier: electricity-cost · Formula version: tncalc.electricity-cost.1.0.0 · Engine release: 6.6.1. Build provenance · Public validation · Release history.