How Our Calculators Work
Every estimate on this site uses a straightforward formula. Here's exactly how we calculate heating costs — no black boxes, no guesswork.
The Core Formula
Cost = (Wattage ÷ 1,000) × Hours × Electricity Rate ($/kWh)
Cost = (BTU/hr ÷ Efficiency) × Hours × Fuel Rate
We start with your heater's output
Electric heaters are rated in watts (e.g., 1,500W). Gas and propane heaters are rated in BTU/hr. We divide watts by 1,000 to get kilowatts, or divide BTU output by efficiency to get actual fuel consumption.
We apply your local utility rate
Default rates come from the U.S. Energy Information Administration (EIA) — state-average residential electricity prices ($/kWh) and natural gas prices ($/therm). You can override these with your actual bill rate for a more precise estimate.
We multiply by your usage hours
You tell us how many hours per day and days per month you run the heater. Longer run times increase cost linearly — double the hours, double the cost.
For heat pumps, we factor in COP
Heat pumps move heat rather than generate it, so we divide electricity consumption by the Coefficient of Performance (COP). A COP of 3 means 3 units of heat output per 1 unit of electricity input.
Annual estimates add heating degree days
State-level annual cost projections use Heating Degree Days (HDD) data from NOAA to account for how cold — and how long — winters are in your region.
Data Sources
- U.S. EIA — Form EIA-861M (monthly residential electricity prices by state)
- U.S. EIA — Natural gas residential prices by state
- NOAA — Annual Heating Degree Days (HDD) by state
- DOE — Typical equipment efficiency ratings (HSPF, COP, AFUE)