Floor Area Ratio Calculator
Construction
Calculate floor area ratio with explicit inputs and a worked example.
Formula
FAR = total floor area / site area
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Enter floor area as defined by the applicable local planning rules.
Example Calculation
Example inputs
- Total floor area: 300 m²
- Site area: 200 m²
300 m² of floor space on a 200 m² site gives a ratio of 1.5.
Frequently asked questions
How do I use this calculator?
Enter total floor area, site area. The result updates automatically. Use Reset to restore the example values.
What method does it use?
FAR = total floor area / site area. Enter floor area as defined by the applicable local planning rules.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.