AC Unit Cost

Air conditioning is sold by the ton - a unit of cooling, not of weight - and once you know that, a quote stops being a mystery and starts being arithmetic. One ton is 12,000 BTU/h of cooling. A 4 ton unit does 48,000.

What a central AC costs, installed

Bands are indicative 2026 US contractor ranges from published cost guides (HomeGuide, Angi). They are not a quote.

Read that table again: the price per ton falls

This is the part almost nobody explains, and it changes how you read a quote.

1.5 ton:  $4,700 - $6,500  ÷ 1.5  =  ~$3,100 - $4,300 per ton
5   ton:  $7,000 - $9,500  ÷ 5    =  ~$1,400 - $1,900 per ton

More than double the cooling for well under double the money. The reason is simple: a big slice of an AC job is the same work whatever hangs off the end of it - the trip, the line set, the electrical, the permit, the labor of getting the old unit out and the new one in. The box scales. The job does not.

So a contractor quoting a flat $/ton figure across sizes is not quoting the job as it is actually done, and a quote that looks cheap per ton on a big unit is not a bargain - it is arithmetic.

Efficiency moves it again

SEER2 is the efficiency label on the box, and all you need to know is that a higher number means less electricity for the same cooling. 13.4 is roughly the entry level; 20 and up is the premium end.

That is a genuine doubling for the same tonnage. Whether it pays back depends on your climate, your electricity price and how long you will own the house - in a hot, long cooling season it can; in a mild one it is a long wait. Price it, do not assume it.

Bigger is not safer - the one thing to take away

The estimating rule is one ton per 500 sq ft, so a 2,000 sq ft house prices at about 4 tons. Use it to price the job. Then stop using it, because it systematically oversizes - ACCA’s own data puts real Manual J load calculations nearer 1,400 sq ft per ton than 500.

And an oversized air conditioner is a worse air conditioner. Not more expensive-but-fine. Worse:

• It cools the air faster than it dehumidifies it. Pulling moisture out takes run time, and a big unit satisfies the thermostat and shuts off before it has had any.
• The house ends up cold and clammy rather than cool and dry - which is the feeling people blame on the unit being too small, and then oversize again.
• It short-cycles - runs in short bursts and shuts off again - which is hard on a compressor.

That is why cooling should be rounded to the nearest size actually built - and there is no 4.5 ton unit; the line goes 4, then 5 - while heating rounds up. Two opposite rules, both deliberate. Furnace replacement cost covers the other one.

How the price is built

tons = floor area ÷ (sq ft per ton)  → round to the NEAREST size built

ac unit cost = tons × $ per ton
             + ductwork (seal, repair or new)
             + line set, electrical, pad
             + permit and inspection
             + removal of the old condenser

The calculator sets that $ per ton from the size you land on - reloading it as the size changes, because the rate genuinely moves - and lets you type over it, which is how you price a high-efficiency unit. Run yours through the AC replacement cost calculator for a low-typical-high band, then price the lines locally.

What moves the total

• Tonnage, which should come from a load calculation, not from the floor plan.
• Efficiency tier, which roughly doubles the condenser between the bottom and the top.
• The ductwork. Undersized or leaking ducts throttle a new unit and are the reason some houses never feel fixed.
• The indoor coil. A condenser is rated as a matched pair with the coil it feeds - a new outdoor unit on an old indoor coil does not deliver its rated efficiency.
• Access. A ground-level condenser on a concrete pad against an accessible wall is the easy version of this job.
• A heat pump instead, which cools and heats and is priced $3,500 to $8,800 by size for the unit and a basic install.

Worked example

A 2,000 sq ft house replacing a dead central AC.

1. Size for pricing: 2,000 ÷ 500 = 4 tons → $6,500 - $8,800 installed at the entry efficiency tier.
2. Get the Manual J done anyway. At ACCA’s real-world average nearer 1,400 sq ft per ton, this house may genuinely need closer to 3 tons - which is a $5,800 - $7,800 unit, and a better-performing one.
3. Step 2 saved money and improved the result. That is the whole argument for the load calculation, in one line.
4. Add the ducts if they leak ($400 - $1,900), the permit, and the removal.

The rule of thumb sold you a bigger machine that works worse. Do not let it.

Where AC quotes go wrong

• Sizing off square footage. It oversizes. It is a pricing shortcut, not a design.
• “Go one size up to be safe.” There is no safe direction here. Up is cold and clammy.
• Paying for a SEER2 20+ condenser feeding leaking ducts. The ducts are cheaper and matter more.
• Mixing a new condenser with an old indoor coil and expecting the rated efficiency. They are rated as a pair.
• Budgeting on a tax credit without checking it still exists. The US federal 25C credit was repealed for anything placed in service after 31 December 2025 (One Big Beautiful Bill Act, P.L. 119-21), and Canada’s Greener Homes Grant is closed. Check before you count on it.

If the furnace is the same age as the AC, price the pair before committing to either - HVAC replacement cost is the full-system version of this page.