Electric Heating Cost Calculator
Calculate the electricity cost of heating a room from room size, insulation, temperature difference, heater efficiency, and electricity rate.
Shows daily and monthly costs.
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.