What it calculates
Cost = power (kW) × electricity rate (USD/kWh) × hours. The U.S. Department of Energy says: “The amount of electricity a customer uses over time is measured in kilowatt-hours (kWh).” Last checked November 13, 2026. A kilowatt-hour is the unit identity behind that product. This is not a heat-pump efficiency multiplier.
Worked example, not your equipment: 10 kW × USD 0.16/kWh × 1 hour = USD 1.60. The same identity gives 5 kW × USD 0.16/kWh × 1 hour = USD 0.80, and 15 kW × USD 0.16/kWh × 1 hour = USD 2.40. The full product is calculated first. The displayed cost is then rounded to the nearest cent, with a half cent rounded up.
What it does not do
Gas, oil and “not sure” are refused. Do not invent a kW rating for them. Compressor, blower, fixed fees, taxes, tiered or time-of-use rates and other household loads are excluded. A thermostat’s Aux runtime is not proof that every strip ran at full nameplate power, or that all stages were on. If the rating is unknown, leave the power field empty and ask for documentation. The frame does not fill in 10 kW.
Accepted entries are 0.01–100 kW, 0–10 USD/kWh and 0–744 hours. Power and hours allow two decimal places; the rate allows six. These are input limits, not equipment ratings or a recommended runtime. Zero hours is valid arithmetic, not a promise of free heat. Outdoor temperature is not an input and does not select a lockout. This page does not list thermostat lockout temperatures.
Embed this calculator
Copy the frame and the credit link together. Leave the link followable. The frame is 1280px tall so the source line and credit link stay visible in a narrow column. The instruction page stays unframeable; only the calculator frame can be embedded.
Sources and last checked: U.S. Department of Energy, Electricity 101. “The amount of electricity a customer uses over time is measured in kilowatt-hours (kWh).” Last checked November 13, 2026. Cost = kW × USD/kWh × hours. The full product is calculated first, then the displayed cost is rounded to the nearest cent, with a half cent rounded up. Electricity 101. Calculation and input limits.