Calculate BTU needs, compare heating costs, size your AC or furnace, and estimate energy savings — all for free. No signup, no guesswork.
BTU calculators, AC tonnage, furnace sizing, ductwork, heat load, and mini-split calculators.
SEER savings, insulation R-value, window U-factor, air leak costs, thermostat savings, and energy audits.
Heating cost comparison, radiant floor, boiler sizing, heat pump COP, fireplace efficiency, and fuel costs.
Ceiling fan sizing, whole-house fans, attic ventilation, evaporative coolers, dehumidifiers, and air purifiers.
Calculate how many BTUs you need to heat or cool a room based on its size, insulation level, climate zone, and sun exposure.
Determine the right air conditioner size in tons for your home based on square footage, climate, and home characteristics.
Perform a simplified Manual J heat load calculation for your home to determine heating and cooling requirements.
Compare the annual cost of heating your home with natural gas, electricity, propane, oil, and heat pumps side by side.
Calculate how much you can save by upgrading to a higher SEER-rated air conditioner. Compare old and new systems side by side.
Calculate the total R-value of your wall or attic assembly and see if you meet recommended levels for your climate zone.
Rate your home energy efficiency with a simple self-audit. Get a score from 0 to 100 and personalized improvement recommendations.