Uses the same engine as the full calculator (occupants 2, one large window assumed).
| Cooling load | — |
Common 300 sq ft room dimensions: 15×20 ft, 12×25 ft, 10×30 ft. The load depends on area, not shape.
US (single room): at roughly 22 BTU per sq ft, 300 sq ft carries about 6,600 BTU/hr, which the DOE room air conditioner chart matches to a 7,000 BTU window or portable unit. The smallest residential central system is 18,000 BTU — installing one here would oversize the room by 2.7× and cause short-cycling.
| US climate zone | Cooling load | Room unit |
|---|---|---|
| Zone 1 — Hot (FL, S.TX, AZ desert) | 8,400 BTU/hr | 9,000 BTU |
| Zone 2 — Warm (Deep South, TX) | 7,500 BTU/hr | 8,000 BTU |
| Zone 3 — Moderate (TN, NC, MO) | 6,600 BTU/hr | 7,000 BTU |
| Zone 4 — Mild (Mid-Atlantic, PNW) | 6,000 BTU/hr | 6,000 BTU |
| Zone 5 — Cool (Upper Midwest, New England) | 5,400 BTU/hr | 6,000 BTU |
India (single room, split AC): at hot-climate loads (~100 BTU/sq ft once ceiling and sun factors apply), a 300 sq ft room needs about 30,000 BTU/hr → a 2.5 ton split. Top floor under an RCC roof, or large west-facing windows? Step up half a ton or pick a high-ISEER model.
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.
0.75 ton 1 ton 1.5 ton 2 ton 2.5 ton 3 ton 3.5 ton 4 ton 5 ton
About 6,600 BTU/hr in a moderate US climate, which matches a 7,000 BTU window or portable unit.
No. The smallest residential central system is 18,000 BTU, which is 2.7× the load of a 300 sq ft room. It would short-cycle and leave the room cold and humid.
A 2.5 ton split — Indian room loads run near 100 BTU/sq ft once ceiling height and sun are counted.
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How these figures are derived: BTU per square foot, honestly · refine for your exact room with the full tonnage calculator.