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    AC Cooling Load Calculator (BTU) — Free Manual J Lite

    Is it bad to oversize an air conditioner?

    Yes. An oversized AC cools the air quickly but shuts off before it removes enough humidity, leaving the house cold and clammy and short-cycling the compressor (which shortens its life and wastes energy). Right-sizing from a Manual J load calc — not from square-footage rules of thumb — gives longer run times and far better comfort and dehumidification.

    Run the numbers for your project

    Use the AC Cooling Load Calculator (BTU) — Free Manual J Lite to get an exact answer for your inputs.

    Open the calculator

    Related questions

    Estimates and general guidance only. Verify against your local code and AHJ before any installation. Gas, electrical, and refrigerant work is hazardous to untrained users.

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