What this calculator does
Floor area ratio (FAR) works out ratio of building floor area to lot size, and the max floor area a zoning FAR limit allows. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaFAR = total floor area / lot area; maximum allowed floor area = FAR limit × lot area
The inputs explained
| Field | What to enter |
|---|---|
| Lot area (sq ft) | A number, measured in sq ft. Starts at 6000. |
| Total building floor area (sum of all floors) (sq ft) | A number, measured in sq ft. Starts at 3000. |
| Local FAR limit (zoning cap) | A number. Starts at 0.5. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with lot area
Every other input is held at the calculator’s starting values while lot area varies. Select any row to load that scenario into the calculator.
How the answer changes with lot area