Small parts, big consequences
Square inches are the unit of louvers, filters, speaker grilles and the print area on labels — anything sized in inches that needs to fit in a hole sized in inches. The calculator converts to square feet too, because ventilation specs often flip between the two mid-document.
Sources and standards
Where these figures come from
Every formula on this page is implemented from the published reference material below. Where a value depends on a regional code, the calculator lets you override it rather than assuming one jurisdiction.
- NIST Office of Weights and Measures — the US customary and SI conversion factors used throughout this tool.
- International Code Council — the International Residential Code and International Building Code.
Figures, formulas and reference tables last verified: 19 September 2026.