What size heat pump do I need for a 4,000 sq ft house?

About more than 5 tons (two systems). In a mixed climate like Atlanta the estimate is 5+ tons (cooling load 59,400 BTU/h, heating load 76,000 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 4,000 square feet?

For cooling, roughly 65,000 BTU/h in a hot, dry climate and 51,000 BTU/h in a cold one. For heating, from 60,000 to 120,000 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 4,000 sq ft house?

Short answer: more than 5 tons (two systems), depending on your climate and insulation. In a mixed climate like Atlanta: more than 5 tons.

By climate

Hot and dry (Phoenix)5+ ton
Hot and humid (Houston)5+ ton
Mixed (Atlanta)5+ ton
Cold (Chicago)5+ ton
Very cold (Minneapolis)5+ ton

Average insulation, 8 ft ceilings, three occupants.

Work it out for your home

Pre-filled with 4,000 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: Multi-zone
Central / ducted size: Over 5 ton
Cooling load: 65,000 BTU/h
Heating load: 60,000 BTU/h

This is more than one indoor unit can handle well - look at multi-zone systems or a ducted central heat pump.

See mini-splits See 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 65,000 · heating 60,000
Hot and humid (Houston)cooling 65,000 · heating 60,000
Mixed (Atlanta)cooling 59,400 · heating 76,000
Cold (Chicago)cooling 56,600 · heating 108,000
Very cold (Minneapolis)cooling 51,000 · heating 120,000

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

Poor5+ ton · heating 98,800 BTU/h
Average5+ ton · heating 76,000 BTU/h
Good5 ton · heating 60,800 BTU/h
Very good5 ton · heating 49,400 BTU/h

Questions3

What size heat pump do I need for a 4,000 sq ft house?: About more than 5 tons (two systems). In a mixed climate like Atlanta the estimate is 5+ tons (cooling load 59,400 BTU/h, heating load 76,000 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 4,000 square feet?: For cooling, roughly 65,000 BTU/h in a hot, dry climate and 51,000 BTU/h in a cold one. For heating, from 60,000 to 120,000 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