How Many BTUs Does My Air Conditioner Need?

“It is hot up in the biznasty,” you may find yourself saying as the heat wave blankets your town in boiling sun rays. Air conditioning is your primary defense against this scourge and you may need to buy a new one or upgrade an old one. The first question is how many BTUs do you need? This handy chart helps you figure that out:

Via EnergyStar.gov: Square footage – BTUs

100 up to 150 – 5,000
150 up to 25 – 6,000
250 up to 300 – 7,000
300 up to 350 – 8,000
350 up to 400 – 9,000
400 up to 450 – 10,000
450 up to 550 – 12,000
550 up to 700 – 14,000
700 up to 1,000 – 18,000
1,000 up to 1,200 – 21,000
1,200 up to 1,400 – 23,000
1,400 up to 1,500 – 24,000
1,500 up to 2,000 – 30,000
2,000 up to 2,500- 34,000

If you don’t know your square footage, just multiply the length by the width. If you need to calculate for a triangular area, multiply the length by the width and divide by two.

If the room gets lots of shade, reduce BTUs by 10%.
If it’s very sunny, increase BTUs by 10%.
If the room has more than two people in it on a regular basis, add 600 BTUs for each.

For more info on which A/C to get, check out publishing sibling Consumer Reports air conditioner buying guides and ratings.