FAR Calculator

FAR is a zoning metric equal to a building's total (gross) floor area divided by the lot's area: FAR = floor area ÷ lot area. A FAR of 1.0 means the floor area can equal the lot area; a FAR of 2.0 allows floor area up to twice the lot size (typically achieved by building multiple stories).

Multiply your zoning district's allowed FAR by your lot's area: maximum floor area = FAR × lot area. For example, a 3,000 sq ft lot in a zone with a 4.0 FAR limit allows up to 3,000 × 4.0 = 12,000 sq ft of total floor area across all stories.

Generally yes — FAR typically counts the gross floor area of every story, which is how a small lot can still support a large total floor area by building multiple stories. Exact rules on what counts (basements, parking garages, mechanical space) vary by local zoning code.

Check your local zoning ordinance or contact your municipality's planning/zoning department — allowed FAR varies by zoning district and is set locally, not by any national standard.

Many zoning codes exclude parking structures, mechanical penthouses, stairwells, elevator shafts, open balconies, and uncovered roof decks from the gross floor area used in FAR calculations — meaning a building can sometimes have more usable space than the raw FAR number suggests. Exact exclusions vary by jurisdiction, so confirm with your local zoning code.