Floor Area Ratio (FAR) Calculator

Calculate maximum building floor area from lot size and FAR zoning limits, accounting for setbacks and lot coverage requirements.

Inputs

Lot Area

sq ft

FAR Limit

Number of Floors

Max Lot Coverage

Lot Width

Lot Depth

Front Setback

Side Setback

Rear Setback

Tab to move between fields

Results

Max Floor Area (by FAR)

40,000 sq ft

≈ 9 basketball courts

Planned Floor Area

48,000 sq ft

≈ 11 basketball courts

Actual FAR2.4

FAR ComplianceNo — exceeds FAR limit

Building Footprint12,000 sq ft

Open Space8,000 sq ft

Open Space %40%

Potential Residential Units53

Est. Building Height48 ft

Coverage CompliantYes

How to Use This Calculator

Enter Lot Area, FAR Limit, and Number of Floors.
Set Max Lot Coverage, Lot Width, and Lot Depth.
Adjust Front Setback, Side Setback as needed.
Review Max Floor Area (by FAR) (sq ft) and Planned Floor Area (sq ft).
Use Actual FAR and FAR Compliance to inform your decision.

How the result changes with Lot Area

Lot Area	Max Floor Area (by FAR)	Planned Floor Area
50,900	101,800 sq ft	52,800 sq ft
175,650	351,300 sq ft	52,800 sq ft
325,350	650,700 sq ft	52,800 sq ft
450,100	900,200 sq ft	52,800 sq ft

What each input means

Lot Area: Total lot area in square feet.
FAR Limit: Maximum Floor Area Ratio allowed by zoning. Suburban: 0.3-0.5, Urban: 1.0-5.0, Downtown: 5-15+.
Number of Floors: Planned number of above-grade stories.
Max Lot Coverage: Maximum percentage of lot that the building footprint may cover.
Lot Width: Width of the lot at the building line.
Lot Depth: Depth of the lot from front to rear property line.
Front Setback: Required distance from front property line to building.
Side Setback: Required distance from side property line to building (each side).
Rear Setback: Required distance from rear property line to building.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Lot Area = 20000, FAR Limit = 2, Number of Floors = 4, Max Lot Coverage = 60 = 9 input(s) provided
Calculate Max Floor Area
Max Floor Area
40000 = 40000
Calculate Planned Floor Area
Planned Floor Area
48000 = 48000
Calculate Actual FAR
Actual FAR
2.4 = 2.4
Calculate FAR Compliance
No — exceeds FAR limit = No — exceeds FAR limit

Engine last updated August 5, 2026. Checked against 2 independently-derived tests — how we verify calculators.

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