Free HVAC Sizing Calculator

Your Recommendation

2.5 tons

30,000 BTU/hr

Recommended Size Range

2.0 – 3.0 tons

Based on Manual J simplified formula

Estimated Installation Cost

$4,750 – $7,000

Includes equipment + labor in your city

Base BTU (sq ft × 25) 37,500

Climate adjustment +15%

Insulation adjustment 0%

Stories adjustment 0%

Final BTU load 43,125

This estimate uses a simplified Manual J formula. Actual sizing requires an in-home load calculation by a licensed HVAC tech. Costs reflect 2025–2026 Sunbelt market averages.

Learn About AC Installation →

How the Calculator Works

Our calculator uses a simplified version of Manual J — the industry-standard HVAC sizing methodology. Here's what each factor means for your system.

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Square Footage

The base rule of thumb: roughly 1 ton of cooling capacity per 600 sq ft, or 25 BTU per square foot. Larger homes need proportionally larger systems, but not always linearly — layout and ceiling height matter too.

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Climate Zone

Extreme heat cities like Yuma (summer highs 110°F+) require 20–25% more cooling capacity than national averages. Kansas City, with more moderate summers, requires a smaller upsize. Climate is the single biggest variable in Sunbelt sizing.

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Insulation Quality

Poor insulation (older homes, single-pane windows, no attic insulation) can increase the cooling load by 15%+. Good insulation (spray foam, double-pane windows, R-38 attic) can reduce the required tonnage by 10%, saving on equipment cost.

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Number of Stories

Multi-story homes have more exterior wall surface area relative to square footage, which increases heat gain. A 3-story home adds roughly 10% to the cooling load versus a single-story home of the same square footage.

HVAC Installation Cost by City

Installed cost (equipment + labor) per ton, 2025–2026 Sunbelt market rates:

City	Cost / Ton	Typical 2-Ton	Typical 3-Ton	Typical 5-Ton
🌵 Yuma, AZ	$2,200–$3,200	$4,400–$6,400	$6,600–$9,600	$11,000–$16,000
🌵 Tucson, AZ	$2,100–$3,100	$4,200–$6,200	$6,300–$9,300	$10,500–$15,500
🌪️ Tulsa, OK	$1,900–$2,800	$3,800–$5,600	$5,700–$8,400	$9,500–$14,000
🌿 Greenville, SC	$2,000–$2,900	$4,000–$5,800	$6,000–$8,700	$10,000–$14,500
🌾 Kansas City, MO	$1,800–$2,700	$3,600–$5,400	$5,400–$8,100	$9,000–$13,500

Costs reflect 2025–2026 market averages for split-system central AC replacement. New construction, high-efficiency systems (18+ SEER2), or complex ductwork may cost more.

HVAC Sizing FAQ

Is bigger always better for AC?

No — and oversizing is a common mistake. An oversized AC unit cools the space too fast, causing short-cycling: the unit runs briefly, shuts off, then runs again. This wastes energy, wears out the compressor, and leaves the home humid because the unit doesn't run long enough to remove moisture from the air. Always size to your actual load, not "just in case."

What's the difference between tons and BTU?

1 ton of cooling = 12,000 BTU/hr. The "ton" term comes from the cooling power of melting one ton of ice over 24 hours (which absorbs 12,000 BTU/hr). Modern HVAC systems are rated in both tons and BTU — they're just different units for the same thing. Common residential sizes: 1.5 ton (18,000 BTU), 2 ton (24,000), 2.5 ton (30,000), 3 ton (36,000), 4 ton (48,000), 5 ton (60,000).

Why is sizing different in Sunbelt cities?

Sunbelt cities run 2–3× more cooling hours per year than northern states. Extreme summer temperatures (105–115°F in Phoenix, Yuma, or Tucson) mean the delta between outdoor and desired indoor temperature is much larger, requiring proportionally more cooling capacity. The "Rule of 600 sq ft per ton" assumes moderate climates — in extreme heat zones, that drops to 400–500 sq ft per ton for proper sizing.

Should I trust this calculator or get a Manual J done?

Use this as a starting point, not a final answer. A proper Manual J calculation by a licensed HVAC technician accounts for window placement, ceiling height, local design temperatures, duct leakage, and other factors that a simplified formula can't capture. That said, most reputable HVAC contractors size homes very close to what this calculator produces — it's a solid sanity check before getting quotes.

What SEER2 rating should I choose?

Minimum federal standard for Sunbelt states (IECC Zones 1–3) is 15 SEER2 for new equipment. For Sunbelt homes where cooling costs dominate the utility bill, a 16–18 SEER2 unit typically pays back the upcharge in energy savings within 4–7 years. Systems 18+ SEER2 with variable-speed compressors offer the best efficiency but cost $1,500–$3,000 more upfront.

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