Air Conditioner Tonnage Calculator
Estimate air conditioner size from room area.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Air Conditioner Tonnage Calculator
How to use this tool
- Enter your values in the fields above.
- Press Generate. The result appears below the buttons.
- Use Load sample to see a worked example, or Clear to start again.
Worked example
For a 1,200 sq ft room with an 8 ft ceiling: 1,200 x 20 = 24,000 BTU/h, which is 24,000 / 12,000 = 2.00 tons.
What this tool does not do / Limits
This is a rough sizing estimate only. It ignores insulation, windows, sunlight, climate, occupancy and heat from appliances, so a real installation needs a proper load calculation.
Frequently asked questions
Why 20 BTU per square foot?
It is a common rough rule for a normally insulated room. A sun-facing room with large windows may need more, and a well-shaded room may need less.
Should I round up or down?
Round to the nearest standard size, and do not greatly oversize: an oversized unit cools fast but dehumidifies poorly and cycles on and off.
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