BTU & Room Size

Bigger isn’t always better! Maximize your unit’s performance with these tips from Energy Star to enjoy a room that’s cool, dry & comfortable. Portable options (think window units & rolling models) are best-suited for single-area use.

Calculate room square footage:

• Square & rectangular rooms: Multiply length by width.
  (e.g., L. 12 ft. x  W. 10 ft. = 120 sq. ft.)
• Triangular rooms: Multiply the longest length by the longest width & divide by two. 
  ( e.g. L. 13 ft. x W. 15 ft. = 195 sq. ft. ÷ 2 = 97.5 sq. ft.) 
• Complex shapes: Subdivide into squares/rectangles & triangles, then use above formulas to calculate total square footage.

Use square footage to choose an A/C unit with the BTU capacity needed to cool that area:

Then adjust BTUs with the following considerations:

• Reduce BTU capacity by 10% for heavily shaded rooms

• Increase BTU capacity by 10% for very sunny rooms

• Add 600 BTUs for every person who regularly occupies the room
  (beyond two)

• Add 4000 BTUs if unit will be used in a kitchen