What Size AC for a 2,000 Sq Ft Home in Buffalo?

What size AC a 2,000 sq ft Buffalo home needs

Start with 20 BTUs per square foot and you get 40,000 BTUs, call it a 3 or 3.5 ton unit, for 2,000 square feet. Treat that as a first guess. The number that should go on the contract comes out of a Manual J load calculation, and a drafty 1915 Kenmore house can come out quite differently from a 2005 build in Clarence with the same floor area.

Last reviewed October 29, 2026 · Citations at the bottom

Where the 20 BTU figure comes from

This Old House offers 20 BTUs for each square foot of living space as a rough opening estimate. Multiply by 2,000 and you have 40,000 BTUs. A ton of cooling equals 12,000 BTUs an hour, so that is about 3.3 tons, which in the real catalog means choosing between a 3 ton and a 3.5 ton unit. This Old House itself tells readers to get a load calculation.

Why Manual J should settle it

The Department of Energy's guidance is to size from the actual heating and cooling loads of the house, worked out with ACCA Manual J. Rules of thumb, it says, push people toward oversized systems that waste energy and short-cycle. A DOE guide written for contractors makes the same point: oversizing often happens because a contractor used a shortcut instead of a calculation.

In this area, these are what shift the answer:

Wall insulation. Plenty of pre-war Buffalo houses have little or none, and a top floor under an uninsulated roof bakes.
Glass. Original single-pane windows let in afternoon sun and sticky lake air.
Moisture. Too much capacity drops the temperature quickly and shuts off before it has wrung water out of the air, so the house ends up cool and damp.
Ceiling heights, how open the layout is, and whether the attic or third floor is living space.

Two houses of identical square footage on the same Tonawanda block can need different equipment.

Oversizing costs you twice

A unit that is too big blasts the house cold, shuts off before it reaches efficient running, then restarts a few minutes later. All that cycling wears parts, and the bigger unit cost more up front. When a house won't stay cool, look at the ducts and insulation before blaming the tonnage.

Installed prices by size

Fixr's installed figures: a 3 ton system runs $5,000 to $9,150, a 3.5 ton $5,450 to $9,700, and a 4 ton $6,950 to $11,600. Its $8,750 national average describes a 3 ton, 16 SEER split system with new ducts in a 2,000 square foot house. Full installation costs.

What people around Buffalo want to know

How many tons of cooling does a 2,000 square foot Buffalo house need?

The 20 BTU per square foot shortcut gives roughly 40,000 BTUs, which is 3 to 3.5 tons. A Manual J calculation on your actual house should make the final call.

What does a new AC cost for 2,000 square feet?

Fixr's national average of $8,750 assumes a 3 ton, 16 SEER split system plus new ducts in a 2,000 square foot home. Reusing good existing ducts usually brings it down.