Electric Heating Cost Calculator
Calculate the electricity cost of heating a room from size, insulation, temperature difference, heater efficiency, and rate.
Shows daily and monthly cost.
Heating a space electrically can be cheap or expensive depending on whether you are using resistance heat (100% efficient but costly per BTU) or a heat pump (200-400% efficient because it moves heat rather than generating it).
Heat load calculation
The simplified heat load formula for residential spaces:
BTU/hour = room area (sq ft) x ceiling height (ft) x 0.133 x delta T (F) x insulation factor
Insulation factors: poor (old home, single-pane windows) = 0.20, average = 0.15, good (modern, well-insulated) = 0.10.
The constant 0.133 accounts for the thermal properties of a typical wall assembly. This is a rough estimate — a proper Manual J calculation by an HVAC engineer considers window area, infiltration, duct losses, and climate data.
Efficiency and COP
Electric resistance heaters (baseboard, plug-in space heaters): 100% efficient. Every watt in becomes one watt of heat.
Heat pumps: A coefficient of performance (COP) of 2.5-4.0 means for every watt of electricity consumed, you get 2.5-4 watts of heat. A COP of 3 means 300% effective efficiency.
kWh/hour = (BTU/hr) / 3,412 / (efficiency/100)
Daily cost = kWh/hour x run_hours x electricity_rate
Space heater reality check
A 1,500 W space heater running 8 hours a day costs about $1.56 at $0.13/kWh. Per month that is $47. For a single room that is often more than heating the whole house with gas. Electric resistance heat is convenient but expensive compared to gas or a heat pump — unless you have cheap electricity (solar, hydro regions) or are only supplementing.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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