Maintained by the BuildSolver engineering team · Updated
AC size · 2,000 sq ft
What size AC for a 2,000 sq ft house
A 2,000 sq ft house needs anywhere from 1 ton to 4.5 tons of cooling in the 14 climates below. The low end is a tight 2015 house in San Francisco, CA and the high end is a 1985 house with attic ducts in Phoenix, AZ. The 400 to 600 sq ft per ton rule gives 3.33 to 5 tons for all of them. Check your zone first.
Run your own house in the calculator. It starts with a 2,000 sq ft two-story house in Albuquerque, NM, built in 1985 with ducts in the attic.
- Type the 5-digit ZIP of the job. The calculator looks up the climate zone and its design temperatures.
- Enter the conditioned floor area, stories and year built. The form starts at 2,000 sq ft.
- Pick air tightness, foundation and window type, and check the box if the ducts run through an unconditioned attic.
- Read the cooling load and tonnage, then find the row for your climate zone in the table below to see how the envelope changes the size.
Example result for the default inputs
ZIP 87102 · Bernalillo County, NM · IECC zone 4B · elevation 4,982 ft · design 95°F DB / 66°F WB cooling, 14°F heating
Cooling load
27,213BTU/h
≈ 2.5 ton (nearest 0.5) · SHR 0.97
Heating load
39,261BTU/h
- Furnace input bin 60,000 BTU/h at 80% AFUE
- Heat pump 60,000 BTU/h at 47°F (40,650 at design temp)
- Flagged for a dual-fuel system
Load breakdown by component
| Component | Cooling | Heating |
|---|---|---|
| Transmission (walls, ceiling, floor, glass, doors) | 8,347 | 25,332 |
| Solar through glass | 12,253 | - |
| Infiltration | 863 | 7,386 |
| Internal gains (people, appliances) | 2,920 | - |
| Ducts in unconditioned attic | 2,830 | 6,543 |
- These design temperatures are the worst case for the IECC climate zone. BuildSolver estimates ZIP-level values can differ by 2-8°F.
- These are preliminary design conditions. For a permit load, take the design temperatures from ASHRAE Handbook - Fundamentals 2021, Chapter 14.
- Recommended 2.5 tons rounds to 110% of computed load. Per ACCA Manual S, oversize >115% may impair dehumidification. Consider a 2-stage or variable-capacity unit.
For estimation purposes only. Consult a licensed engineer for final designs.
Room-by-room Manual J and branded PDF reports · Pro plan
How the tonnage in the table is calculated
Each of the 28 cells in the table is its own run of the BuildSolver load engine on a 2,000 sq ft house, using the whole-house Speed Sheet simplification of ACCA Manual J 8th Edition. The AC size hub has the full method and every floor area side by side.
- House geometry
footprint = 2,000 / 2 = 1,000 sq ft; side = 32 ftThe engine models a square two-story footprint with 8 ft ceilings, which gives about 2,024 sq ft of gross wall and 1,000 sq ft of ceiling under the attic.- Tonnage
tons = Q_cool / 12,000, rounded to the nearest 0.5Loads are rounded to the nearest half ton, which puts this floor area between 1 ton and 4.5 tons.- Square feet per ton
sq ft per ton = 2,000 / (Q_cool / 12,000)Computed from the unrounded load. Across this table one ton covers 450 to 2,013 sq ft.
AC size for a 2,000 sq ft house in 14 climate zones
Each row is the same 2,000 sq ft two-story house on a slab with 4 occupants and glass at 15% of floor area. Only the climate zone and the envelope change. The first house column is a 1985 build with average air sealing and ducts in a vented attic. The second is a 2015 build with a tight envelope and ducts inside conditioned space. Tons are rounded to the nearest half ton. Each cell also shows the load in BTU/h and how many square feet one ton covers.
| Zone | Reference city | Cooling design | 1985 house, attic ducts | 2015 house, ducts inside |
|---|---|---|---|---|
| 1A | Miami, FL | 92°F | 3.5 tons41,204 BTU/h · 582 sq ft/ton | 1.5 tons20,480 BTU/h · 1,172 sq ft/ton |
| 2A | Houston, TX | 96°F | 3.5 tons43,946 BTU/h · 546 sq ft/ton | 2 tons21,903 BTU/h · 1,096 sq ft/ton |
| 2B | Phoenix, AZ | 110°F | 4.5 tons53,305 BTU/h · 450 sq ft/ton | 2 tons26,756 BTU/h · 897 sq ft/ton |
| 3A | Atlanta, GA | 95°F | 2.5 tons30,086 BTU/h · 798 sq ft/ton | 1.5 tons19,766 BTU/h · 1,214 sq ft/ton |
| 3B | Las Vegas, NV | 100°F | 2.5 tons32,246 BTU/h · 744 sq ft/ton | 2 tons21,384 BTU/h · 1,122 sq ft/ton |
| 3C | San Francisco, CA | 84°F | 2 tons21,068 BTU/h · 1,139 sq ft/ton | 1 ton13,843 BTU/h · 1,734 sq ft/ton |
| 4A | St. Louis, MO | 92°F | 2.5 tons27,108 BTU/h · 885 sq ft/ton | 1.5 tons18,000 BTU/h · 1,333 sq ft/ton |
| 4B | Albuquerque, NM | 95°F | 2.5 tons27,213 BTU/h · 882 sq ft/ton | 1.5 tons18,334 BTU/h · 1,309 sq ft/ton |
| 4C | Seattle, WA | 84°F | 1.5 tons17,587 BTU/h · 1,365 sq ft/ton | 1 ton11,921 BTU/h · 2,013 sq ft/ton |
| 5A | Chicago, IL | 91°F | 2 tons26,493 BTU/h · 906 sq ft/ton | 1.5 tons16,963 BTU/h · 1,415 sq ft/ton |
| 5B | Denver, CO | 93°F | 2 tons26,011 BTU/h · 923 sq ft/ton | 1.5 tons16,807 BTU/h · 1,428 sq ft/ton |
| 6A | Minneapolis, MN | 90°F | 2 tons23,969 BTU/h · 1,001 sq ft/ton | 1.5 tons15,735 BTU/h · 1,525 sq ft/ton |
| 6B | Billings, MT | 92°F | 2 tons23,784 BTU/h · 1,009 sq ft/ton | 1.5 tons15,770 BTU/h · 1,522 sq ft/ton |
| 7 | Duluth, MN | 86°F | 1.5 tons19,659 BTU/h · 1,221 sq ft/ton | 1 ton13,041 BTU/h · 1,840 sq ft/ton |
Only 3 of the 28 engine results land inside the rule-of-thumb range of 3.33 to 5 tons, the 1985 house in zones 1A, 2A and 2B.
In Phoenix, AZ the 1985 house with attic ducts needs 4.5 tons and the tight 2015 house with its ducts inside needs 2 tons, 2.5 tons apart on the same floor area.
The highlighted Albuquerque row is the calculator's starting point. There the 1985 house needs 27,213 BTU/h, or 2.5 tons, and a heating load of 39,261 BTU/h at 14°F. Built tight in 2015 with the ducts inside, the same house needs 1.5 tons. A 500 sq ft per ton quote would put 4 tons on both. Size each house from its own row, then check the existing ducts and registers before you write the quote.
Standards and data sources
- ACCA Manual J 8th Edition - residential load procedure. The tables use its whole-house Speed Sheet simplification, which gives a single load for the whole house.
- ACCA Manual S - equipment selection against the Manual J load, including the 115% limit on cooling capacity for a single-speed unit. Selection is a separate step and part of the Pro plan.
- IECC 2021 climate zones (PNNL county map) - ZIP to county to climate zone. The zone sets the design temperatures, solar factor and envelope defaults for each row.
What the table leaves out
- Every row is one standard 2,000 sq ft house. On a real job, insulation, glass, orientation and air leakage move the load, and in this table the 1985 and 2015 builds in Phoenix, AZ already land 2.5 tons apart.
- Each row uses the worst-case design temperature of its IECC climate zone, from 84°F in the San Francisco zone to 110°F in the Phoenix zone. BuildSolver estimates ZIP-level values can differ by 2-8°F, and ASHRAE Handbook - Fundamentals 2021, Chapter 14, lists the city values.
- The engine treats both stories as one zone. The page cannot split the load between floors, and a bonus room over a garage is not modeled.
- Whole-house load only. Room-by-room Manual J and Manual S equipment selection are part of the Pro plan.
Common sizing mistakes on a 2,000 sq ft house
- Quoting 5 tons because the house is 2,000 sq ft. That is the top of the 400 sq ft per ton rule. In the St. Louis, MO row the engine puts the 1985 house at 2.5 tons and the 2015 house at 1.5 tons.
- Reusing the tonnage from a job in another market. The same 1985 house with attic ducts needs 1.5 tons in Seattle, WA and 4.5 tons in Phoenix, AZ.
- Sizing off the nameplate of the unit coming out. It may have been picked by rule of thumb, and matching it repeats whatever oversizing the last installer chose.
- Letting the heating load set the AC. In Duluth, MN the 1985 house needs 63,738 BTU/h of heat and 1.5 tons of cooling. Pick the furnace and the AC from their own loads.
What to check on a 2,000 sq ft house
The 2,000 sq ft houses on this page are two-story, three-bedroom homes with the bedrooms upstairs, matching the 4 occupants in the load. The second floor carries more of the cooling load because it sits under the attic and gets the heat that rises from below, so one system on one thermostat often leaves the upstairs warm. Expect the first comfort callback from the upstairs bedrooms in July.
- The quick form treats the house as one zone. On a two-story house the upstairs often carries more of the cooling load on a hot afternoon, so check the duct split between floors before you trust one thermostat.
- At this size, look at two small systems or one zoned variable-speed system. The whole-house number here sets the total. The room-by-room Manual J in the Pro plan gives each room's load, so you can add up each floor.
- Stair openings move air between floors. Put returns high on the second floor so the upstairs air gets back to the air handler.
Questions about AC size for 2,000 sq ft
What size AC do I need for a 2,000 sq ft house?
Climate and construction decide it. In the table on this page the answer runs from 1 ton in San Francisco, CA to 4.5 tons in Phoenix, AZ. In Chicago, IL the same house comes out at 2 tons as a 1985 build and 1.5 tons as a 2015 build. Enter your ZIP and the house details in the calculator for your own number.
How many BTU does a 2,000 sq ft house need for cooling?
The cooling loads in the table run from 11,921 to 53,305 BTU/h. Per square foot that is 6 to 26.7 BTU/h, so no single BTU per square foot number fits a house this size. Run the actual house in the calculator above for its number.
Is a 5-ton AC too big for a 2,000 sq ft house?
ACCA Manual S limits a single-speed cooling unit to 115% of the Manual J load. By that limit a 5-ton single-speed unit is oversized for the 1985 house in 13 of the 14 climates and for the 2015 house in 14 of them.
What size furnace goes with a 2,000 sq ft house?
The heating loads in the same runs go from 11,218 to 63,738 BTU/h, the highest for the 1985 house in Duluth, MN. With the engine's AFUE default for the year built, those loads call for furnace inputs from the 40,000 to the 80,000 BTU/h bin. The furnace size calculator shows the heating result for a single ZIP.
Why does a 2,000 sq ft house need a different size in Phoenix and Seattle?
Design temperature and solar load. The table uses 110°F for the Phoenix zone and 84°F for the Seattle zone, so the same 1985 house needs 4.5 tons in Phoenix and 1.5 tons in Seattle.
Can I quote a 2,000 sq ft job from this table?
Use it for the first conversation with the homeowner. In Albuquerque, NM the same 2,000 sq ft comes out at 2.5 tons or 1.5 tons depending on how the house was built, so run the load for the actual house before you order equipment. Room-by-room Manual J and Manual S equipment selection are in the Pro plan. If the job needs a permit, ask the building department whether it requires a load report from ACCA-approved software.
Used on the same job
Size the actual house in chat
Start with the ZIP. Then describe the house you are quoting, including the windows, insulation and where the ducts run, and the assistant runs the same load tools, asks for what is missing and explains the result in terms you can show the homeowner.
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