HVAC Calculators
24 calculators24 free calculators for hvac homeowners.
Sizing your equipment
The size to shop for, from your square footage, climate and how the house holds heat.
Furnace Size
Find the right furnace size in BTU from your heated square footage, climate, insulation, and ceiling height, using the sizing factors furnace makers publish and the industry 100–140% sizing window. Picks the standard size (40,000–120,000 BTU) that fits, and flags when a home is too small or too large for one furnace.
Heat Pump Size
Find what size heat pump you need in tons for your square footage and climate, and whether a standard or cold-climate model is right for your winters.
Wood Stove Size
Find the right wood stove size for your room or house, and the firebox to shop for, from your square feet, insulation and climate.
Humidifier Size
Find what size humidifier you need, in gallons per day, for one room or the whole house, from its size, how drafty it is and your winter.
Dehumidifier Size
Find the dehumidifier size your basement or room needs from its square feet and how damp it gets, in today's pint ratings and the older ones.
Replacing, installing and repairing
What a new system, a repair or a cleaning should cost.
Furnace Replacement Cost
Replacing a gas furnace costs $3,800–$12,000 installed depending on home size and AFUE efficiency — electric furnaces run just $1,700–$7,200. Price your fuel, size, and efficiency tier in seconds.
Central AC Replacement Cost
Replacing central AC costs $4,500–$7,000 for a small home and $7,000–$11,500 for a typical 2,000 sq ft house — before efficiency upgrades. Price your size and SEER tier, and see when repair beats replacement.
Mini-Split Installation Cost
Estimate the professionally-installed cost of a ductless mini-split AC/heat pump by number of zones, square footage, and climate. See the per-zone cost and the full range — and why you can no longer count on the $2,000 federal tax credit for 2026 installs.
Geothermal Heat Pump Cost
Estimate what a geothermal (ground-source) heat pump costs to install by home size and ground-loop type — horizontal, vertical, pond, or open-loop. The loop field is the biggest cost driver. Shows the real price before incentives, and why the 30% federal tax credit no longer applies in 2026.
Whole-House Humidifier Cost
Estimate the installed cost of a whole-house humidifier by type — bypass, fan-powered, or steam — plus water-line and humidistat add-ons. See why the type drives the price, and the one requirement (forced-air heating) that decides if you can even add one.
Whole House Fan Cost
A whole-house fan costs $600–$2,300 installed — and then $3–$24 a month to run, against central AC's $80–$200. Price your home size and wiring, and see whether the old-school cooler fits your climate.
Bathroom Exhaust Fan Cost
Replacing a bathroom fan costs $150–$550; installing one from scratch with new wiring and outside venting runs $250–$950+. Price your job and fan type — and see what size fan your bathroom actually needs.
HVAC Repair Cost Estimator
Estimate what an HVAC repair should cost before you say yes to a quote. Pick the part, your system, and your local labor rate to see a fair total for parts, labor, and the service fee.
HVAC Duct Cleaning Cost
Estimate air-duct cleaning cost the honest way — a flat price per HVAC system, not per vent. See typical 2026 prices, dryer-vent and sanitizing add-ons, what the EPA actually says about whether you need it, and how to avoid the $49 'whole-house special' scam.
Running costs and savings
What heating, cooling and the small appliances cost to run, and what changes save.
Firewood
Find how many cords of firewood your house needs for a winter, in full cords and face cords, from its size, your climate and what you burn it in.
Wood Pellet
Find how many 40-lb bags of wood pellets your stove will burn this winter, what they will cost, and how much it goes through on a midwinter day.
Gas Fireplace Running Cost
See what your gas fireplace costs to run per hour and per month on natural gas or propane, plus what leaving the pilot light on adds.
Heat Pump vs Gas Furnace
Compare a heat pump against a gas furnace for your home. See your annual heating cost each way, the payback period on the extra upfront cost, and net savings over time.
Electric Baseboard Heating Cost
See what one room costs to heat with electric baseboard for a month, from the room size, how it holds heat, the weather and where you set the thermostat.
Thermostat Setback Savings
See how much you save by turning your thermostat down in winter or up in summer. Anchored to your real bill using the Department of Energy’s setback rule of thumb.
AC vs. Evaporative Cooler
In dry climates a swamp cooler runs on about one-fourth the electricity of central AC. Compare annual operating costs — power and water — for your home and climate, including the honest answer for humid regions.
Space Heater Running Cost
See what a space heater costs to run per hour, per day and per month from its wattage, the hours it runs and your electricity rate.
Basement Dehumidifier Running Cost
Estimate what it costs to run a basement dehumidifier — per month and per year — by unit size (pint capacity), ENERGY STAR, how damp the basement is, and your electricity rate. See why the biggest savings come from fixing the moisture, not the setpoint.
Air Purifier Running Cost
Calculate what an air purifier really costs to run — electricity by size, hours, and your kWh rate, plus the replacement filters that usually cost more than the power. ENERGY STAR savings included.
About HVAC Calculators
Your HVAC system typically accounts for 40-50% of your home's energy bill, making sizing and efficiency decisions among the most consequential choices you'll make for your property. Unlike most home systems, an undersized unit will run constantly without reaching your target temperature, while an oversized unit cycles on and off inefficiently—both scenarios cost you thousands in wasted energy. Our HVAC calculators help you determine what your home actually needs based on square footage, climate zone, insulation quality, and window efficiency, so you can avoid overpaying for unnecessary capacity or underpaying for insufficient cooling and heating.
Whether you're replacing an aging system, shopping for quotes from contractors, or trying to understand why your utility bills have spiked, these tools give you the technical foundation to make decisions with confidence. You'll learn to calculate your home's heating and cooling load, estimate seasonal energy costs for different efficiency ratings, and compare the long-term value of high-SEER units against cheaper alternatives. Many homeowners save thousands by catching contractor oversizing before signing a contract, and others recoup equipment costs through lower monthly bills within five to seven years.
Start with your home's square footage and local climate, then use our calculators to get the specific numbers you need for conversations with contractors or to validate the recommendations you've already received.