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AC Sizing Calculator
Buying a window unit or estimating central AC? Get a quick BTU estimate based on room size and a few sanity-check factors. Note: full Manual J is more accurate for whole-house decisions — see our Pro tool.
Enter the room area.
FAQ
Bigger AC is better, right? +
Wrong. An oversized AC cools fast but doesn't run long enough to remove humidity — you get cold + clammy. Right-sizing matters.
What's a 'ton' of cooling? +
12,000 BTU/hr = 1 ton. A typical home needs 2–5 tons total. A bedroom needs 5,000–10,000 BTU.
When do I need Manual J? +
For whole-house central air decisions, get a real Manual J load calculation. This calculator is a rough check, not a permit-grade tool.