What size air conditioner do I need for my house?

AC size depends on your home's cooling load, not just square footage. A 2,000 sq ft home might need 2.5 tons in a mild climate but 4 tons in a hot, humid climate. Use our calculator above for a personalized recommendation based on your ZIP code, insulation, and home details.

How many tons of AC do I need for 2000 sq ft?

For a 2,000 sq ft home with average insulation: in a hot climate (Zone 2), you typically need 3-4 tons. In a mixed climate (Zone 4), 2.5-3.5 tons. In a cold climate (Zone 6), 2-3 tons. These are estimates -- actual tonnage depends on insulation quality, windows, and other factors.

What is a ton of AC cooling?

One ton of air conditioning equals 12,000 BTU/hr of cooling capacity. The term comes from the amount of heat needed to melt one ton of ice in 24 hours. Residential AC units typically range from 1.5 to 5 tons.

What happens if my AC is too big?

An oversized AC short-cycles (turns on and off frequently), causing poor humidity control, uneven temperatures, higher energy bills, and increased wear on the compressor. Proper sizing using Manual J calculations prevents these problems.

What SEER rating should I get?

The federal minimum is SEER2 14.3 (as of 2023). For hot climates (Zones 1-2), we recommend SEER2 16+ for energy savings. For mixed climates, SEER2 15+ is a good balance. For cold climates where AC usage is lower, the minimum SEER2 14.3 is adequate.

How accurate is this tonnage calculator?

This calculator uses simplified ACCA Manual J methodology with real climate zone design temperatures. Estimates are within +/-20%. For exact, permit-ready sizing, upload your blueprints to AutoHVAC for a full Manual J report.

AC Tonnage Calculator: What Size Air Conditioner Do I Need?

Free AC tonnage calculator. Enter your square footage and ZIP code to find the right air conditioner size in tons. Based on ACCA Manual J methodology.

Enter Your Details

Conditioned Square Footage

ZIP Code

Stories

Insulation / Home Age

Window Area

Foundation Type

Your AC Sizing

Enter your details on the left to see results.

AC Tonnage by Home Size and Climate Zone

Recommended AC tonnage ranges for average insulation, 9 ft ceilings. Your actual needs may vary by insulation, windows, and other factors.

Home Size	Hot Climate Zone 2 (tons)	Mixed Climate Zone 4 (tons)	Cold Climate Zone 6 (tons)
800 sq ft	1 - 1.5	1 - 1.5	1 - 1.5
1,000 sq ft	1 - 1.5	1 - 1.5	1 - 1.5
1,200 sq ft	1 - 1.5	1 - 1.5	1 - 1.5
1,500 sq ft	1 - 2	1 - 2	1 - 1.5
1,800 sq ft	1 - 2	1 - 2	1 - 2
2,000 sq ft	1 - 2	1 - 2	1 - 2
2,500 sq ft	1.5 - 2.5	1.5 - 2.5	1.5 - 2.5
3,000 sq ft	2 - 3	1.5 - 2.5	1.5 - 2.5
3,500 sq ft	2 - 3	2 - 3	2 - 3
4,000 sq ft	2.5 - 3.5	2.5 - 3.5	2 - 3
5,000 sq ft	3 - 4	3 - 4	2.5 - 3.5

Based on simplified ACCA Manual J. 1 ton = 12,000 BTU/hr cooling capacity.

How We Calculate This

Air conditioner tonnage is determined by your home's total cooling load, measured in BTU/hr. One ton equals 12,000 BTU/hr of cooling capacity. Here is how we calculate it:

Calculate cooling load: Envelope heat gain through walls, ceiling, floor, and windows based on outdoor design temperature minus indoor setpoint (75F).
Add solar gains: Window area multiplied by ACCA Manual J solar factors (varies by orientation, 19-68 BTU/hr per sqft) and window SHGC.
Add internal gains: Heat from people (230 BTU/hr each), appliances (2,100 BTU/hr), and lighting (500 BTU/hr).
Add infiltration and latent loads: Air leakage brings in hot, humid outdoor air. Latent load depends on wet-bulb temperature.
Convert to tons: Total cooling BTU/hr divided by 12,000 = tonnage. Rounded to nearest 0.5 ton for standard equipment sizes.

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