Central AC Replacement Cost in 2026
A new central air conditioner runs $3,900–$7,900 installed in 2026, the range driven mainly by tonnage (system size) and SEER2 efficiency tier rather than brand. A correctly-sized entry-tier system for a small-to-mid-size home sits toward the low end; a larger home needing more tonnage, or a higher SEER2 tier for lower running costs, sits toward the high end. See the full HVAC replacement cost guide for how this compares to a full furnace-plus-AC system.
| Item | Typical installed cost |
|---|---|
| Correctly-sized, entry-tier SEER2 | Low end of range |
| Larger tonnage for home size | Moves toward high end |
| Higher SEER2 tier (quieter, lower bills) | Moves toward high end |
| Oversized system (wrong for the home) | Higher cost, worse performance, not a feature |
Tonnage drives more of the price than people expect
Tonnage measures cooling capacity, not weight: one ton equals 12,000 BTU/h of cooling. A rough starting point is 1 ton per 500-600 sq ft, refined by a real Manual J load calculation that accounts for insulation, windows, ceiling height and climate zone. Bigger tonnage costs more, but bigger is not automatically better: an oversized unit short-cycles, switching on and off repeatedly rather than running a full cooling cycle, which wastes energy, leaves the home more humid than it should be, and wears the equipment out faster. The right tonnage for your actual home, not the biggest one a contractor has in stock, is what should drive the number: see the HVAC replacement cost guide's home-size breakdown for a starting estimate.
SEER2 tier: the other half of the price
SEER2 (Seasonal Energy Efficiency Ratio 2) measures cooling output over a typical season divided by the energy it takes to produce it: higher is more efficient and costs less to run, at a higher upfront price. An entry-tier system at your region's DOE minimum (13.4 SEER2 in northern states, 14.3 in the South and Southwest) sits at the bottom of the price range; stepping up a tier or two for lower summer electric bills and quieter operation moves the quote up, and a premium high-SEER2 inverter-driven system sits at the top. Whether the extra efficiency pays for itself depends on your local electricity rate and how many hours a year the system actually runs, in a market like Miami, where cooling runs nearly year-round, premium SEER2 tiers pay back fastest; see the SEER2 ratings guide for the real payback math.
Why two "same size" quotes can differ this much
A 3-ton system at the DOE minimum SEER2 and a 3-ton system two tiers up are both honestly "3-ton," but they are not the same product, and comparing their prices as if they were is the single most common way homeowners misjudge a quote. Always confirm both tonnage and SEER2 tier on every quote you compare: a lower number isn't automatically the better deal if it's a smaller or less efficient system than the one it's being compared against.
Frequently asked questions
What size AC unit do I need for my house?
Roughly 1 ton per 500-600 sq ft as a starting point, refined by a Manual J load calculation a licensed contractor should run before quoting: insulation, window count, ceiling height and climate zone all shift the real number. See the HVAC replacement cost guide for sizing by home size.
Is a higher SEER2 rating always worth paying for?
Not always: it depends on your climate and electricity rate. In a hot climate where the system runs most of the year, the efficiency gain pays back faster. In a milder climate with a short cooling season, an entry-tier system at the regional minimum can be the more cost-effective choice over the system's life.
Can I just replace the outdoor unit and keep my old indoor coil?
Technically sometimes, but it's usually a mistake. Mismatched outdoor and indoor components run below their AHRI-certified rated efficiency and can void the manufacturer's warranty on the new unit. Most contractors recommend replacing the condenser and coil together as a matched system, even though it costs more than replacing the outdoor unit alone.
Sources
Sources cited in this guide. Commercial pricing sources are marked as industry data. Guide last updated October 20, 2026.
- U.S. Department of Energy: 2023 central air conditioner and heat pump standards FAQ (PDF)
- AHRI: AHRI Certification Directory
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