Room Air Conditioner BTU Chart Calculator

Multiply the rectangular room length by width. The calculator converts metric area to square feet and looks up the base cooling capacity in the ENERGY STAR room air conditioner chart. It then applies only the chart's selected sunlight and occupancy adjustments. This is an illustrative U.S. room-AC estimate, not a measured cooling load or approval of a particular unit.

For example, a 15 × 12 ft room is 180 ft². The chart gives 6,000 BTU/h for 150–249 ft². With ordinary sunlight and two occupants, the displayed estimate remains 6,000 BTU/h. With three occupants it is 6,600 BTU/h; a very sunny room with two occupants is also 6,600 BTU/h.

The calculator accepts 100–2,500 ft². It does not extrapolate below or above that chart. Its 8-foot ceiling assumption may not fit tall rooms. It does not model insulation, climate, windows, equipment heat, kitchens, adjoining rooms, or whole-home HVAC loads.

The following U.S. ENERGY STAR chart values are in BTU per hour for an 8-foot ceiling. The calculator treats a boundary such as 150 ft² as the beginning of the next row. The source describes approximate area bands; measure carefully near a boundary.

Source reviewed 29 September 2026. The displayed bands are expressed as nonoverlapping whole-square-foot rows for clarity; the underlying area remains unrounded for lookup.

Following ENERGY STAR guidance, reduce the chart capacity by 10% if the room is heavily shaded, or increase it by 10% if very sunny. Add 600 BTU/h for each regular occupant above two. The form does not choose a sunlight category for you.

Worked example: 180 ft² gives 6,000 BTU/h. A very sunny room with three occupants gives 6,000 × 1.10 + 600 = 7,200 BTU/h. The chart also calls for another 4,000 BTU/h for a kitchen; this form has no kitchen input, so its output does not include that adjustment.

These chart adjustments do not capture heat gains from unusual glazing, poor insulation, appliances, or a different ceiling height. The U.S. Department of Energy describes proper whole-home HVAC sizing as a building load calculation rather than a single area rule.

BTU/h measures cooling capacity. Efficiency is a separate product characteristic. This calculator does not assign an efficiency rating, predict electricity use, or promise savings. For a U.S. room AC, compare the product's CEER and certified status against the current ENERGY STAR room-AC criteria, which vary by product class and capacity.

A chart estimate is a starting point for comparing room units. Installation, moisture removal, actual room heat gains, and available product sizes can change the appropriate choice. Source pages checked 29 September 2026; consult their current versions when purchasing equipment.