Floor Area Ratio (FAR) Calculator

Find the floor area ratio of a building.

Total floor area

Lot area

FAR 0.6

As percentage (%) 60

Formula: FAR = total floor area ÷ lot area

Step-by-step with your numbers:

1. Values used:

2. Total floor area = 3,000

3. Lot area = 5,000

5. FAR = Total floor area / Lot area = 3,000 / 5,000 = 0.6

6. As percentage = 60%

Did we solve your problem today?

FAR is total floor area divided by the lot size — a key zoning metric.

The math behind it

FAR = total building floor area ÷ lot area. A FAR of 1.0 means the floor area equals the lot.

3,000 ft² on 5,000 ft² → FAR 0.6.

Setback?

FAR is separate from setback/height limits; check your local zoning.