Central Air Installation Cost: By House Size, Tonnage and SEER
Air conditioning is priced by tonnage and efficiency, then again by whether you have ducts. This calculator prices the system; ductwork is a separate line.
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Installed unit price only. New ductwork adds $3,600 to $9,500, and a retrofit into a house without ducts is nearly three times the labour of a change-out.
By house size
| House | Installed |
|---|---|
| 800 sq ft | $2,320 – $5,760 |
| 1,000 sq ft | $2,900 – $7,200 |
| 1,200 sq ft | $3,480 – $8,640 |
| 1,500 sq ft | $4,350 – $10,800 |
| 2,000 sq ft | $5,800 – $14,400 |
| 2,500 sq ft | $7,250 – $18,000 |
| 3,000 sq ft | $8,700 – $21,600 |
| 3,500 sq ft | $10,150 – $25,200 |
A 2,000 sq ft house is the national reference point because it is where the most common unit size — 3 tons — lands.
By system size
| Size | Installed |
|---|---|
| 1.5 tons (18,000 BTU) | $3,650 – $6,250 |
| 2 tons (24,000 BTU) | $4,250 – $7,500 |
| 2.5 tons (30,000 BTU) | $4,500 – $8,000 |
| 3 tons (36,000 BTU) | $5,000 – $9,150 |
| 3.5 tons (42,000 BTU) | $5,450 – $9,700 |
| 4 tons (48,000 BTU) | $6,950 – $11,600 |
| 5 tons (60,000 BTU) | $7,800 – $14,000 |
Most homes need 3 to 3.5 tons. A 5-ton unit exists but is oversized for almost every house, and an oversized unit is worse than an undersized one: it cools the air without removing the humidity.
Efficiency is where the range comes from
| SEER / SEER2 | Grade | Unit only |
|---|---|---|
| 14 / 13.4 | Standard (North) | $1,725 – $3,600 |
| 15 / 14.3 | Standard (South) | $2,300 – $4,800 |
| 16 / 15.3 | High | $2,875 – $6,000 |
| 17 / 16.2 | High | $3,450 – $6,600 |
| 18 / 17.2 | High | $4,100 – $7,800 |
| 19 / 18.1 | Very high | $4,600 – $8,400 |
| 20 / 19.1 | Very high | $5,750 – $9,600 |
| 21 / 20 | Very high | $6,325 – $10,800 |
The difference between a 14 SEER and a 21 SEER unit of the same size is roughly four times the equipment cost. Whether that pays back depends entirely on how many hours a year you run it.
In a hot climate with a long cooling season, high SEER pays back. In a northern state that uses air conditioning a few weeks a year, it never does.
The ductwork is often the bigger number
Labour to install a system on existing ducts runs $1,250 to $3,000. Adding new ducts is another $965 to $2,325 in labour plus the material.
Retrofitting ducts into a house that never had them is nearly three times the labour, because they have to be routed through closets, between floors and under stairs. That is the $8,650 to $20,200 band.
The practical rule: if the house already has ducts, central air is a moderate project. If it does not, consider a ductless mini-split before you commit.
Sizing is not a square-footage formula
| Zone | BTU per sq ft | Typical states |
|---|---|---|
| Zone 1 | 50 – 60 | Florida, south Texas, southern Arizona |
| Zone 2 | 45 – 50 | Gulf states, inland California |
| Zone 3 | 40 – 45 | Mid-Atlantic, mid-South |
| Zone 4 | 35 – 40 | Northern Midwest, mountain states |
| Zone 5 | 30 – 35 | Minnesota, Maine, Montana |
The climate-zone multiplier is the honest starting point, but a proper quote uses a Manual J load calculation that also accounts for insulation, window area and orientation, and air leakage.
Ask whether the contractor ran one. A quote based purely on square footage is a guess with a price attached.
What it costs in six states
Material does not change at the state line. Labour does. These are the same 2,000 sq ft job priced with six different wage markets.
| State | Labour factor | Low | High |
|---|---|---|---|
| Oklahoma | ×0.79 | $5,639 | $13,407 |
| Kentucky | ×0.84 | $5,793 | $13,789 |
| West Virginia | ×0.92 | $5,991 | $14,282 |
| New Hampshire | ×1.08 | $6,398 | $15,292 |
| New Jersey | ×1.38 | $7,184 | $17,243 |
| Illinois | ×1.40 | $7,247 | $17,398 |
Only the labour line moves. That is a stated limitation of this model, not an oversight.
Frequently asked
Replace or repair?
Air conditioners last ten to twenty years. Past fifteen, a major repair is usually money spent on a machine that is near the end.
Does a new AC raise home value?
Not directly in the way a kitchen does. It matters at inspection and at sale, but nobody pays a premium for a new condenser.
What is SEER2?
A newer test method whose numbers run about 4.5% lower than the old SEER figures for the same equipment. A 16 SEER unit is roughly 15.3 SEER2.
Updated October 2026