Central Air Installation Cost Calculator
| System size | Typically cools | 14.3 SEER2 floor | 16 SEER2 | 18+ SEER2 |
|---|---|---|---|---|
| 2 ton | 900-1,100 sq ft | $2,600 | $3,100 | $3,800 |
| 2.5 ton | 1,100-1,400 sq ft | $3,300 | $3,900 | $4,800 |
| 3 ton | 1,400-1,700 sq ft | $3,900 | $4,700 | $5,700 |
| 3.5 ton | 1,600-1,900 sq ft | $4,600 | $5,400 | $6,700 |
| 4 ton | 1,800-2,200 sq ft | $5,200 | $6,200 | $7,600 |
| 5 ton | 2,300-2,700 sq ft | $6,500 | $7,800 | $9,500 |
Central air is priced by the ton and the efficiency tier, and the swap is cheaper than the first-time install: a 3-ton system - the most common residential size - lands mid-band around $3,900 installed at the 14.3 SEER2 federal floor, $4,700 at 16, $5,700 at 18+, with honest bands of roughly 70% to 130% of those mids.
The scope checkboxes are where quotes diverge: a straight condenser-and-coil swap on existing copper reuses the line set; replacing the line set adds about $650; replacing the air handler too adds about $1,850 total in scope. And ducts are never in these numbers - sealing or replacing ductwork is its own trade with its own quote, from $1,000 in sealing to several thousand in new runs.
The efficiency floor moved in 2023: split-system air conditioners must now reach 13.4 SEER2 in the North and 14.3 in the Southeast/Southwest under the new test procedure - and SEER2 numbers read lower than old SEER for identical hardware, so a 14.3 SEER2 unit is not a step down from a 14 SEER one.
How to use
- Size by the rule of thumb, then verify: 450-550 sq ft of cooling per ton covers most homes, so 2,000 sq ft lands near 3.5-4 tons - a Manual J calc settles it, and oversizing cools fast but dehumidifies badly.
- Pick the efficiency tier with your run-hours in mind: in Phoenix or Houston the 16+ tier pays back in a few seasons; in Minneapolis the floor tier is usually the rational buy.
- Set the scope honestly - look at your line set age (insulated copper on the exterior wall) and whether the air handler or furnace blower was replaced in the last decade.
- Compare against two or three bids and make duct condition, pad, permit and haul-away explicit line items, not allowances.
Frequently asked questions
How much does it cost to install central air?
The common 3-ton system lands mid-band at $3,900 installed at the federal-floor 14.3 SEER2, $4,700 at 16, $5,700 at 18+, with bands of roughly 70-130% of mid. A straight swap sits at the bottom of the band; first-time installs needing line set, air handler, pad and electrical upgrades climb toward the top. Ductwork is separate - budget $1,000-5,000 more if ducts are new or failing.
What size AC do I need for my house?
Start at 450-550 sq ft per ton: 2,000 sq ft lands near 3.5-4 tons, 1,200 near 2.5. Sun, shade, insulation and ceiling height move it either way, which is why the Manual J calculation exists - and why bigger is not safer: an oversized unit cools the air fast, shuts off, and never wrings out the humidity, which is the clammy feeling people mistake for a weak AC.
Should I install a heat pump instead of AC-only?
If you heat with gas and love it, AC-only is the simpler machine. But a heat pump is the same hardware plus a reversing valve - typically $500-1,500 more installed - and it replaces or supplements your furnace with 200-300% efficient electric heat. The federal floor for split heat pumps is 14.3 SEER2 with a 7.5 HSPF2, so the efficiency baseline is the same machine either way.
Why did my old 16 SEER become 13.4 SEER2?
It did not - the test procedure changed in January 2023. SEER2 runs the blower against higher static pressure, so the same hardware scores about 0.3-0.5 SEER lower on the new scale: a 15 SEER unit is roughly a 14.3 SEER2 unit. Never compare a SEER number to a SEER2 number; compare only within the same scale, and check the EnergyGuide label which now prints SEER2.
Does a central air quote include ductwork?
Almost never in full: quotes assume existing ducts in serviceable condition, and the inspection happens mid-job - which is why duct condition is the first thing to settle. Sealing and minor repairs run $1,000-3,000; replacing ducts in an unconditioned attic can add several thousand and sometimes more than the equipment. Ask the bidder to price duct sealing as its own line before signing.