AC decision guide
AC Size & Tonnage: Why Load Calculation Matters
AC tonnage describes cooling capacity, but the correct capacity depends on the home's actual heating and cooling loads rather than a universal square-feet-per-ton shortcut.
The decision this page helps with
How should I think about AC capacity before selecting replacement equipment?
Use tonnage as a capacity concept and rely on proper load calculation for actual equipment sizing.
What the reviewed evidence supports
load calculation
Residential equipment sizing should be based on a recognized load calculation process rather than a simplistic square-foot table.
What can change the decision or cost
- actual design cooling load
- equipment capacity
- duct and building characteristics
Limits and exclusions
- ComfortGauge does not publish a square-feet-to-tonnage table as a substitute for Manual J load calculation.
Reviewed sources and provenance
Quantitative claims are shown only while their required reviewed evidence remains publishable.
- acca manual j — supports load_calculation, equipment_sizing
Frequently asked questions
Is one ton of AC equal to a fixed number of square feet?
No. Building envelope, windows, orientation, infiltration, ducts, climate, and internal loads all affect the required capacity.
Why can an oversized AC be a problem?
A capacity mismatch can contribute to short cycling and comfort or humidity problems, which is why proper load calculation matters.