This calculator sizes a central AC system from home size and climate, then prices the equipment, labor, and any ductwork separately. A 1,000 sq ft home in a cool climate needs a 2-ton unit; the same footprint in a humid climate needs 2.5 tons. At the default 13–15 SEER2, mid-range brand, existing ductwork, that 2-ton system prices at $3,502–$6,290 installed — inside the dataset's own $3,500–$6,500 band for a small home.
How this calculator sizes the system
The starting point is a planning ratio this calculator applies internally: home square footage divided by 500, then adjusted for climate before rounding up to the nearest standard equipment size (1.5, 2, 2.5, 3, 3.5, 4 or 5 tons). That is this tool's own sizing model, not an industry standard — real HVAC sizing is done with an ACCA Manual J heat-load calculation that accounts for insulation, window area, orientation, and duct leakage, none of which a square-footage form can see.
The climate adjustment moves the raw tonnage before rounding: a cool climate multiplies by 0.85, moderate by 1.0, hot by 1.15, and humid by 1.2. So the same 1,000 sq ft home needs 2 tons in a cool climate (1,000 ÷ 500 × 0.85 = 1.7, rounded up to 2) but 2.5 tons in a humid one (1,000 ÷ 500 × 1.2 = 2.4, rounded up to 2.5). That half-ton swing moves every downstream dollar figure, because equipment and labor both scale off a tonnage multiplier keyed to the rounded size.
What the SEER2 rating actually changes
Raising the efficiency tier from 13–15 SEER2 to 16–19 or 20+ moves the equipment price directly — the mid-range 20+ band runs $6,680–$10,540 before the tonnage multiplier is even applied, against $2,920–$4,600 at the base tier. That is the single largest lever in this calculator, larger than climate or brand.
One caveat is worth stating plainly: this page could not independently verify a standalone efficiency-minimum standard for cooling-only central air conditioners. ENERGY STAR's published Key Product Criteria cover heat pumps specifically — split systems at ≥15.2 SEER2/≥11.0 EER2, single-package units at ≥15.2 SEER2/≥10.0 EER2 — and those figures are verified, but a cooling-only AC page distinct from the heat pump criteria was not located. If a contractor cites a SEER2 minimum for a cooling-only system, ask which certification document it comes from; this calculator does not state one as fact.
What this estimate excludes
The ductwork line only appears when it applies. Existing ductwork in good condition adds nothing; repairs add $800–$2,500; and ductwork built from scratch adds $4,000–$8,000 — a separate job priced in more detail on the ductwork installation calculator. There is no federal tax credit built into this estimate: the 25C Energy Efficient Home Improvement Credit, which covered up to $600 for a qualifying central AC, ended for systems placed in service after December 31, 2025. State and utility rebates may still apply and are not modeled here.
Why the same system costs different amounts by region
Labor is roughly a quarter to a third of an installed system, and it is the piece that varies most by where the crew is based. The Bureau of Labor Statistics counted 409,670 HVAC mechanics and installers nationally as of May 2025, with a mean hourly wage of $31.14 and a mean annual wage of $64,780 — just below the $65,360 mean across all construction and extraction occupations. A technician's hourly rate sits inside a wide percentile band, and a quote that lands near the top of this calculator's labor range is often simply reflecting a higher local wage rather than a padded bid.
Methodology
Tonnage is this calculator's own model: home sq ft ÷ 500, adjusted by a climate multiplier (cool 0.85, moderate 1.0, hot 1.15, humid 1.2), rounded up to the nearest standard equipment size. Equipment and labor bands are held in the module and scaled by a per-tonnage multiplier fit to the dataset's own sourced variants (HomeGuide, Angi, This Old House). Wage figures are BLS OEWS May 2025 for SOC 49-9021. No SEER2 minimum for cooling-only equipment is stated as fact; only the verified heat-pump criteria are cited, with that scope made explicit.
Sources
- HomeGuide — AC Replacement/Install Cost (2026) — accessed 2026-07-13
- Angi — Insider's Price Guide: New Heating and Cooling System (2026) — accessed 2026-07-13
- This Old House — Air Conditioner Costs (2026) — accessed 2026-07-13
- U.S. Bureau of Labor Statistics — OEWS Profile, HVAC Mechanics and Installers (49-9021), May 2025 — accessed 2026-09-07
- ENERGY STAR — Heat Pump Equipment Key Product Criteria — accessed 2026-09-07