Heating and Cooling
Size a system and compare what it costs to run.
- Find the right BTU size for a room air conditionerAC BTU calculatorEnter the size of your room to see the cooling capacity to look for in a window or wall air conditioner.Open calculator
- Compare the running cost of window units and central airWindow AC vs central AC costCompare what room air conditioners and a central system cost to run, and see how long a higher price takes to pay back.Open calculator
- Compare heating a home with a heat pump or a gas furnaceHeat pump vs gas furnace calculatorSee what the same heat costs from a gas furnace and from a heat pump, at your state prices or your own.Open calculator
- Find the right dehumidifier size for a roomDehumidifier sizeEnter your room and how damp it feels to see the capacity ENERGY STAR recommends, then estimate what it costs to run.Open calculator
- Estimate what a smart thermostat could saveSmart thermostat savingsEnter what heating and cooling cost you, and see about what a smart thermostat could save and when it pays for itself.Open calculator
- Compare heating with propane or an electric heat pumpPropane vs electric heating costSee what the same heat costs from a propane furnace and from an electric heat pump at your prices.Open calculator
- Look up the insulation R-value for your climate zoneInsulation R-value by climate zonePick your climate zone and attic to see the R-value ENERGY STAR recommends to add in an existing home.Open calculator
How heating and cooling equipment is sized and compared
Heating and cooling equipment is rated in Btu per hour, where a Btu is the heat needed to warm one pound of water by one degree Fahrenheit. A ton of cooling is 12,000 Btu per hour. Efficiency ratings such as AFUE, HSPF2 and SEER2 say how much of the energy you buy comes back as heat or cooling.
Size and cost are two different questions. The sizing calculators here follow published ENERGY STAR charts for rooms and spaces. A whole-house system is sized by a contractor with a load calculation, and the calculators here do not replace it. The cost calculators multiply the energy a system uses by your price, and let you replace our starting prices with the rates on your bills.
Many choices here depend on the climate where you live and on the fuel you buy. That is why the cost calculators ask for your state or your own prices, and why the comparison between a heat pump and a gas furnace shows a break-even price, the price at which the two cost the same, instead of declaring a winner for everyone.
See how we handle data and formulas on the methodology and sources page.