Uses the same engine as the full calculator (occupants 2, one large window assumed).
| Cooling load | — |
Common 1,800 sq ft floor plans: 36×50 ft, 40×45 ft, 30×60 ft, 25×72 ft. The load depends on area, not shape.
US (whole home): cooling load does not scale linearly with floor area. The building envelope — roof, exterior walls, windows — grows with the perimeter, which rises more slowly than area, so larger homes need fewer BTU per square foot. At 1,800 sq ft the rate works out to about 19.2 BTU/sq ft, giving a design load of 34,500 BTU/hr → 3 ton system.
| US climate zone | Cooling load | System |
|---|---|---|
| Zone 1 — Hot (FL, S.TX, AZ desert) | 43,900 BTU/hr | 4 ton |
| Zone 2 — Warm (Deep South, TX) | 39,200 BTU/hr | 3.5 ton |
| Zone 3 — Moderate (TN, NC, MO) | 34,500 BTU/hr | 3 ton |
| Zone 4 — Mild (Mid-Atlantic, PNW) | 31,300 BTU/hr | 3 ton |
| Zone 5 — Cool (Upper Midwest, New England) | 28,200 BTU/hr | 2.5 ton |
India (room by room): Indian homes are cooled one room at a time, so 1,800 sq ft is not one big unit — it is 7 splits — 2.5T + 1.5T + 1.5T + 1.5T + 1.5T + 1.5T + 1.5T, about 11.5 ton in total. A typical layout at this size breaks down as:
| Room | Approx. area | Split size |
|---|---|---|
| Hall / living | ~504 sq ft | 2.5 ton |
| Bedroom 1 | ~138 sq ft | 1.5 ton |
| Bedroom 2 | ~138 sq ft | 1.5 ton |
| Bedroom 3 | ~138 sq ft | 1.5 ton |
| Bedroom 4 | ~138 sq ft | 1.5 ton |
| Bedroom 5 | ~138 sq ft | 1.5 ton |
| Bedroom 6 | ~138 sq ft | 1.5 ton |
Only cool the rooms you use. Sizing every room at once is how Indian households end up with two unused units and a higher connected load than the sanctioned supply allows — check your meter's sanctioned load before adding the last unit.
Figures assume 8 ft ceilings (9.5 ft for India), average insulation and normal sun. Your real number can swing ±30% — run the full tonnage calculator with your actual room data.
| Area | US | India |
|---|---|---|
| 1,500 sq ft | 2.5 ton system | 6 splits |
| 1,600 sq ft | 3 ton system | 7 splits |
| 1,800 sq ft | 3 ton system | 7 splits |
| 2,000 sq ft | 3.5 ton system | 8 splits |
| 2,200 sq ft | 3.5 ton system | ducted or VRF, ~10.0 ton design load |
0.75 ton 1 ton 1.5 ton 2 ton 2.5 ton 3 ton 3.5 ton 4 ton 5 ton
About 34,500 BTU/hr of design load in a moderate US climate — a 3 ton system.
About 19.2 BTU/sq ft. Larger homes need fewer BTU per square foot because envelope area grows more slowly than floor area.
7 splits — 2.5T + 1.5T + 1.5T + 1.5T + 1.5T + 1.5T + 1.5T — about 11.5 ton in total, cooling room by room.
100 sq ft 120 sq ft 150 sq ft 180 sq ft 200 sq ft 250 sq ft 350 sq ft 400 sq ft 450 sq ft 500 sq ft 600 sq ft 700 sq ft 800 sq ft 900 sq ft 1,000 sq ft 1,100 sq ft 1,200 sq ft 1,300 sq ft 1,400 sq ft 1,500 sq ft 1,600 sq ft 1,800 sq ft 2,000 sq ft 2,200 sq ft 2,400 sq ft 2,500 sq ft 2,800 sq ft 3,000 sq ft 3,200 sq ft 3,500 sq ft 4,000 sq ft 4,500 sq ft 5,000 sq ft
How these figures are derived: BTU per square foot, honestly · refine for your exact room with the full tonnage calculator.