To determine what size air conditioner you need, the primary factor is the square footage of the space you want to cool. The general approach is:

1. Measure the length and width of each room or area to be cooled.
2. Multiply length by width to get the square footage of each room.
3. Add the square footage of all rooms to get the total area.
4. Multiply the total square footage by 20 to 25 to estimate the required BTUs (British Thermal Units), which measure cooling capacity.

For example, if your total space is 1,200 square feet:

• 1,200 x 25 = 30,000 BTUs needed.

Here is a general sizing guide based on square footage and BTUs:

Square Footage| BTUs Needed| AC Size in Tons
---|---|---
Under 600| 12,000| 1
600 - 1,000| 18,000| 1.5
1,000 - 1,500| 24,000| 2
1,500 - 2,000| 30,000| 2.5
2,000 - 2,500| 34,000| 3
2,500 - 3,300| 42,000| 3.5

(1 ton = 12,000 BTUs)

. Additional factors to consider when sizing your air conditioner include:

• Ceiling height (higher ceilings require more BTUs)
• Insulation quality of the home
• Number and size of windows and their sun exposure
• Number of occupants and heat generated by appliances
• Whether the unit is window-mounted or central air

Avoid oversizing the unit, as a too-large AC will short cycle, reducing efficiency and comfort

. If you want to cool multiple rooms or an entire home, it is best to consult a professional HVAC technician for a detailed load calculation to ensure optimal sizing and efficiency

. In summary, calculate your total square footage, multiply by about 20-25 BTUs per square foot, and select an air conditioner with the corresponding BTU capacity to meet your cooling needs.