HVAC Size Calculator
Find the right size air conditioner, heat pump, or furnace for your home. Don't overpay for too much unit or suffer with too little.
Total area you want to heat/cool. Don't include unfinished basements or garages.
Your HVAC Size Recommendation
Estimated Equipment Cost (2026)
📍 In the Kansas City metro? Get your exact price.
The figures above are national averages. If you're in the Kansas City area and ready to move forward, Cross Mechanical — a licensed, locally owned HVAC company (5.0★ from 45+ reviews) — will give you a real, no-pressure quote. Honest $85 service call.
Get My Real Quote →⭐ Keep Your HVAC Healthy Between Service Calls
Three items that pay for themselves on any HVAC system — they extend equipment life and cut energy bills more than people realize.
MERV 13 Pleated HVAC Filters (6-pack)
MERV 13 is the sweet spot for residential systems — high enough to catch fine dust and allergens without restricting airflow like MERV 16 filters do. Buy them six at a time and change every 60-90 days. This single habit prevents most blower-motor failures.
View on Amazon →Smart Wi-Fi Thermostat (Nest or Ecobee)
Programmable thermostats from 1995 don't count — a real smart thermostat learns your schedule and can cut HVAC runtime 10-15%. Ecobee includes a remote sensor that fixes hot/cold rooms by averaging temperatures across the house. Pays for itself in a season.
View on Amazon →Whole-Home Dehumidifier (50 pint)
Kansas summers are humid enough that a properly-sized AC runs less than it should because the air feels hotter than the thermostat reads. A 50-pint dehumidifier paired with the HVAC lets you raise the set-point 2-3 degrees and still feel comfortable — lower bills, same comfort.
View on Amazon →As an Amazon affiliate, HomeCalc Tools earns a small commission if you purchase through these links — at no extra cost to you. We only recommend products we would actually use ourselves.
What Size AC Unit Do I Need for My House?
Choosing the right HVAC size is one of the most important decisions you'll make for your home comfort. The general rule of thumb is 1 ton of cooling capacity per 500-600 square feet, but this varies significantly by climate zone, insulation quality, and home characteristics. Our calculator uses a modified Manual J calculation method to give you an accurate recommendation.
Why HVAC Sizing Matters
An undersized system will run constantly, struggle on hot days, and drive up your energy bills. But oversizing is just as bad — an oversized AC unit will short cycle, turning on and off too frequently. This prevents proper dehumidification, creates uneven temperatures, wastes energy, and shortens the equipment's lifespan. Getting the right size means lower bills, better comfort, and equipment that lasts 15-20 years.
HVAC Tonnage Chart by Square Footage
For a moderate climate with average insulation: 600-1,000 sq ft needs 1.5 tons, 1,000-1,500 sq ft needs 2-2.5 tons, 1,500-2,000 sq ft needs 2.5-3 tons, 2,000-2,500 sq ft needs 3-3.5 tons, and 2,500-3,500 sq ft needs 3.5-4 tons. Hot climates add 0.5-1 ton, while well-insulated homes can subtract 0.5 tons.
Central AC vs. Heat Pump: Which Should You Choose?
Heat pumps cost 20-40% more upfront but provide both heating and cooling, and they're significantly more efficient in moderate climates (Zones 2-4). In very cold climates (Zone 5), you may still need a furnace backup. Many states also offer heat pump tax credits and rebates of $2,000-$8,000 through the Inflation Reduction Act, making them increasingly cost-competitive.
What Happens When You Get the Size Wrong
An oversized HVAC system is just as bad as an undersized one — arguably worse, since most homeowners never realize the problem. Oversized AC cools the air too fast and shuts off before it can pull humidity out, leaving a clammy 72-degree house that feels worse than a properly sized 74-degree house. Oversized furnaces cycle on and off rapidly, which wears out the heat exchanger and blower years early. Both scenarios spike your energy bills because short-cycling is the most inefficient way to run any HVAC system. Right-sizing is the cheapest performance upgrade you'll ever buy — it costs nothing extra at purchase and pays back in lower bills and a longer equipment life.
The Manual J Conversation You Should Have
If a contractor proposes a system size without doing a Manual J load calculation — a room-by-room measurement of your home's heat gain and loss — politely ask them to do one. Manual J is the industry standard and any reputable HVAC contractor knows it. If they refuse or claim "experience" is enough, that's a sign they're guessing, and guesses tend to round up (oversized). Our calculator above gives you a credible second opinion before you sign anything.