What Size AC Do I Need? AC & Heat Pump Size Calculator (BTU and Tons)

What size AC or heat pump do I need?

Cooled living area (sq ft)Sun exposureCeiling height

40,000 BTU/hestimated cooling capacity

3.3 tons1 ton = 12,000 BTU/h

3.5 tonsnearest standard size to discuss

For a 1,600–2,000 sq ft home, a 3-ton central AC is the size most often installed.

Before you buy, ask for a Manual J load calculation. Insulation, windows, ducts, climate and layout change the right size a lot. Most US building codes require equipment to be sized this way, and an oversized unit short-cycles, removes less humidity and wears out sooner.

Estimate only. Whole-home figures use the U.S. Department of Energy rule of about 20 BTU per square foot; single rooms use the ENERGY STAR room AC sizing chart and its adjustments.

AC size chart by square feet

Estimated cooling capacity at 20 BTU per square foot with 8-foot ceilings and average sun, the size it rounds to, and the size most often installed for that home size.

Home size	Estimated BTU/h	Tons	Nearest standard size	Most often installed
1,000 sq ft	20,000	1.7	1.5 tons	1.5 tons
1,200 sq ft	24,000	2.0	2 tons	2.5 tons
1,500 sq ft	30,000	2.5	2.5 tons	2.5 tons
1,600 sq ft	32,000	2.7	2.5 tons	2.5 tons
1,800 sq ft	36,000	3.0	3 tons	3 tons
2,000 sq ft	40,000	3.3	3.5 tons	3 tons
2,200 sq ft	44,000	3.7	3.5 tons	3.5 tons
2,400 sq ft	48,000	4.0	4 tons	3.5 tons
2,500 sq ft	50,000	4.2	4 tons	3.5 tons
3,000 sq ft	60,000	5.0	5 tons	–
3,500 sq ft	70,000	5.8	5 tons	–

Sources: U.S. Department of Energy (20 BTU per sq ft); Angi, 2026 (most often installed). Residential central systems usually come in half-ton steps from 1.5 to 5 tons.

Room air conditioner BTU chart

For window units, portable units and single-zone mini-splits, ENERGY STAR publishes this chart, with four adjustments: subtract 10% for a heavily shaded room, add 10% for a very sunny room, add 600 BTU for each person beyond two, and add 4,000 BTU for a kitchen (ENERGY STAR).

Area to cool	Capacity
100–150 sq ft	5,000 BTU/h
150–250 sq ft	6,000 BTU/h
250–300 sq ft	7,000 BTU/h
300–350 sq ft	8,000 BTU/h
350–400 sq ft	9,000 BTU/h
400–450 sq ft	10,000 BTU/h
450–550 sq ft	12,000 BTU/h
550–700 sq ft	14,000 BTU/h
700–1,000 sq ft	18,000 BTU/h
1,000–1,200 sq ft	21,000 BTU/h
1,200–1,400 sq ft	23,000 BTU/h
1,400–1,500 sq ft	24,000 BTU/h
1,500–2,000 sq ft	30,000 BTU/h
2,000–2,500 sq ft	34,000 BTU/h

Why a Manual J load calculation beats any rule of thumb

Square-foot rules ignore the things that change cooling load most: insulation, window area and direction, air leakage, duct location and local design temperatures. A Department of Energy fact sheet recommends documented Manual J calculations and warns against sizing by floor area or experience alone (DOE).

Oversizing costs comfort: short cycles leave humidity in the air.
It costs energy: in a Florida study, units oversized by 50% or more used about 9% more cooling electricity and had 13% higher peak demand.
It wears equipment: frequent starts and stops shorten its life.
It’s required: the International Residential Code sizes equipment by ACCA Manual S from a Manual J load (IRC M1401.3).

SEER2 minimum efficiency by region

Since January 1, 2023, new split systems must meet these Department of Energy minimums.

Region	Central air conditioner	Heat pump
North	13.4 SEER2	14.3 SEER2, 7.5 HSPF2
Southeast	14.3 SEER2 (13.8 at 45,000 BTU/h and above)	14.3 SEER2, 7.5 HSPF2
Southwest	14.3 SEER2 (13.8 at 45,000 BTU/h and above), plus an EER2 minimum	14.3 SEER2, 7.5 HSPF2

Source: U.S. DOE, 2023 central air conditioner and heat pump standards FAQ (regional SEER2 minimums).

R-410A, R-454B and R-32: the refrigerant change

Under the EPA’s hydrofluorocarbon phasedown, new residential split systems built from January 1, 2025 use lower-impact A2L refrigerants such as R-454B and R-32 (Federal Register). In 2026 the EPA removed the installation deadline for R-410A split systems made before 2025, so remaining stock can still be installed, and existing R-410A systems can still be serviced (summary).

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Questions

What size AC do I need for a 2,000 square foot house?

Using the Department of Energy rule of about 20 BTU per square foot, 2,000 sq ft needs roughly 40,000 BTU/h, or about 3.3 tons. In Angi’s 2026 data, 3-ton units are most common for 1,600–2,000 sq ft and 3.5-ton units for 2,000–2,500 sq ft. Your insulation, windows and climate decide the final size, so ask for a Manual J calculation.

How many square feet does 1 ton of AC cool?

At 20 BTU per square foot, one ton (12,000 BTU/h) cools about 600 square feet. Well-insulated homes in mild climates may need less, and sunny homes in hot climates more.

Is a bigger air conditioner better?

No. An oversized unit cools the air quickly and shuts off before removing enough humidity, so rooms feel clammy. Frequent starts also waste energy and wear parts. A DOE fact sheet reports that units oversized by 50% or more used about 9% more cooling electricity in a Florida study.

What size mini-split do I need for a 400 sq ft room?

The ENERGY STAR chart gives 9,000 BTU/h for 350–400 sq ft and 10,000 for 400–450 sq ft. Add 10% for a very sunny room, 600 BTU for each extra person beyond two, and 4,000 BTU for a kitchen.

What is a Manual J load calculation?

It is the industry method (from ACCA) that calculates how much heating and cooling a home needs, room by room, from its size, insulation, windows, air leakage, orientation and local climate. The International Residential Code (M1401.3) requires equipment to be sized from it.

Do heat pumps use the same size as an air conditioner?

A heat pump’s cooling size is chosen the same way, but in cold climates its heating capacity at low outdoor temperatures matters too. Cold-climate heat pumps keep more of their capacity in freezing weather, and a Manual J calculation shows whether backup heat is needed.