What size heat pump do I need for a 1,200 sq ft house?

About 2 to 3 tons. In a mixed climate like Atlanta the estimate is 2 tons (cooling load 22,700 BTU/h, heating load 22,800 BTU/h). Hot climates need more cooling capacity and cold climates more heating capacity, as the table shows.

How many BTU do I need for 1,200 square feet?

For cooling, roughly 24,700 BTU/h in a hot, dry climate and 19,500 BTU/h in a cold one. For heating, from 18,000 to 36,000 BTU/h depending on how cold winters get. Older, drafty homes need up to 30% more.

Is it better to oversize or undersize a heat pump?

Neither, but slight undersizing is usually less harmful for cooling. An oversized unit short-cycles and leaves the air clammy. In cold climates, size for the heating load and check the unit’s output at 5°F, or plan for backup heat on the coldest nights.

What size heat pump for a 1,200 sq ft house?

Short answer: 2 to 3 tons, depending on your climate and insulation. In a mixed climate like Atlanta: 2 tons.

By climate

Hot and dry (Phoenix)2 ton
Hot and humid (Houston)2 ton
Mixed (Atlanta)2 ton
Cold (Chicago)3 ton
Very cold (Minneapolis)3 ton

Average insulation, 8 ft ceilings, three occupants.

Best 2-ton heat pumps

Most efficient

Arcoaire B5H3V24KAAA

2 ton central · Deluxe 23 VS Heat Pump · cold-climate certified

SEER2: 23.0
HSPF2: 10.5
Heat at 5°F: 23,000

Top-rated certified model in the size most 1,200 sq ft homes need.

Full specs and running cost

Best for cold winters

York HH824E2S12

2 ton central · LX SERIES · cold-climate certified

SEER2: 18.0
HSPF2: 8.5
COP at 5°F: 2.46

Cold-climate certified, best efficiency at 5°F in this size.

Full specs and running cost

Compare all 2-ton heat pumps

Work it out for your home

Pre-filled with 1,200 sq ft. Pick your city and adjust insulation, sun and ceiling height.

Your space

Area to heat and cool sq ftCeiling heightInsulationSun exposurePeople who usually use itIncludes the kitchen?

Your climate

StateCity

Mini-split size: 24,000 BTU
Central / ducted size: 2 ton
Cooling load: 24,700 BTU/h
Heating load: 18,000 BTU/h

See 24,000 BTU mini-splits See 2-ton central heat pumps

Rule-of-thumb estimate: cooling follows the ENERGY STAR room sizing table, heating uses typical BTU per square foot for the climate (NOAA 1991-2020 heating degree days). For a whole-house system, ask your installer for a Manual J load calculation.

More detail

Cooling and heating loads by climateBTU/h

Hot and dry (Phoenix)cooling 24,700 · heating 18,000
Hot and humid (Houston)cooling 24,700 · heating 18,000
Mixed (Atlanta)cooling 22,700 · heating 22,800
Cold (Chicago)cooling 21,600 · heating 32,400
Very cold (Minneapolis)cooling 19,500 · heating 36,000

Cooling follows the ENERGY STAR sizing table; heating uses BTU per sq ft for the climate (NOAA 1991-2020 normals).

How insulation changes the sizein Atlanta

Poor2.5 ton · heating 29,600 BTU/h
Average2 ton · heating 22,800 BTU/h
Good2 ton · heating 18,200 BTU/h
Very good2 ton · heating 14,800 BTU/h

Top 5 2-ton heat pumpsranked by SEER2

#	Model	SEER2	EER2	HSPF2	COP at 5°F
1	Arcoaire B5H3V24KAAA	23.0	13.5	10.5	2.10
2	Carrier 27VNA324A*030also sold as 1 other model number	23.0	14.0	10.5	2.10
3	Lennox SL25XPV-024-230A	22.8	14.4	9.2	1.88
4	Trane 5TWV0X24A1also sold as 1 other model number	22.4	12.0	10.0	2.20
5	GE NS22H24MA4-**A	22.0	13.5	9.5	2.32

Questions3

What size heat pump do I need for a 1,200 sq ft house?: About 2 to 3 tons. In a mixed climate like Atlanta the estimate is 2 tons (cooling load 22,700 BTU/h, heating load 22,800 BTU/h). Hot climates need more cooling capacity and cold climates more heating capacity, as the table shows.
How many BTU do I need for 1,200 square feet?: For cooling, roughly 24,700 BTU/h in a hot, dry climate and 19,500 BTU/h in a cold one. For heating, from 18,000 to 36,000 BTU/h depending on how cold winters get. Older, drafty homes need up to 30% more.
Is it better to oversize or undersize a heat pump?: Neither, but slight undersizing is usually less harmful for cooling. An oversized unit short-cycles and leaves the air clammy. In cold climates, size for the heating load and check the unit’s output at 5°F, or plan for backup heat on the coldest nights.

Other sizes

All sizing guides