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Housing Unpacked
Glossary

Floor area ratioFAR

A zoning limit expressed as total building floor area divided by lot area; a FAR of 2.0 allows a building with twice as much floor space as the land it sits on.

Floor area ratio is one of the main ways zoning codes control the size of a building. It is the total floor area of all stories divided by the area of the lot. A FAR of 1.0 on a 10,000 square foot lot allows 10,000 square feet of building, which could be one story covering the whole lot or two stories covering half of it.

Floor area ratio
FAR = total building floor area ÷ lot area
Maximum floor area = lot area × maximum FAR

Assume a 40,000 square foot lot zoned for a maximum FAR of 3.0. The largest building allowed has 120,000 square feet of floor area. At an assumed 1,000 square feet of gross floor area per apartment, that is about 120 units.

FAR works together with height limits, setbacks, and lot coverage rules. A generous FAR paired with a strict height limit forces a bulky, low building; a strict FAR with a generous height limit produces a slender tower on a mostly open lot. Codes also differ on what counts as floor area, with some excluding basements, parking, or mechanical space.

For housing costs, FAR is a density control by another name. It caps the number of homes that can share the cost of a site, so a lower FAR means fewer units to spread land and fixed costs across, and higher rent per unit. It is also one of the most common subjects of a rezoning or variance request during entitlement.

Where this comes up

Analysis that uses floor area ratio in the arithmetic.

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