What is the standard FAR formula?

• A. Lot Area divided by (Number of stories times Floor area per story)
• B. (Number of stories times Floor area per story) divided by Lot Area
• C. Total nonresidential floor area divided by Lot Area
• D. Floor area per story divided by Lot Area multiplied by number of stories

Answer: (B)

FAR measures how dense a building project is by comparing the total floor area to the size of the site. The standard way to express it is total floor area divided by the lot area. When each story has the same floor area, the total floor area equals the number of stories times the floor area per story, so FAR can be written as (number of stories × floor area per story) divided by lot area. That is why the correct form matches this expression.

For example, if you have 4 stories and each story is 2,500 square feet on a 12,500-square-foot lot, the total floor area is 10,000 square feet, and FAR = 10,000 / 12,500 = 0.8. This shows how the ratio governs allowable building mass on the site.

The other formulations either misstate the relationship or rely on single-story-area values in a way that isn’t as universal (especially if floor areas vary by story). The robust standard is total floor area divided by lot area, which is equivalently (number of stories × floor area per story) / lot area.