The following table provides a guide for choosing the right size air conditioner based on the area needing to be cooled. The Air conditioner output and capacity is measured in BTU per hour. This chart includes areas from 100 square feet up to 2,500 square feet for comparison.
| Area To Be Cooled (square feet) | Capacity Needed (BTUs per hour) |
|---|---|
| 100 up to 150 | 5,000 |
| 150 up to 250 | 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 |
Additional Considerations
- If the room is heavily shaded, reduce capacity by 10 percent.
- If the room is very sunny, increase capacity by 10 percent.
- If more than two people regularly occupy the room, add 600 BTUs for each additional person.
- If the unit is used in a kitchen, increase capacity by 4,000 BTUs.
- Consider where you install the unit. If you are mounting an air conditioner near the corner of a room, look for a unit that can send the airflow in the right direction.
Measuring for Central Air Conditioning Systems in Tons
The basic formula for determining the required tonnage of a central air conditioning system is as follows:
( ( House square footage times 30 then divided by 12,000 ) – 1.0 ) = Required Tonnage
If you live in an area that has higher temperatures during the summer (such as 110 degrees in the desert) then don’t subtract 1 in the formula above.
To determine a more accurate size for your region, use the chart below.
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Sources (as of 11 May 2017):
Small House Society 