Floor area ratio (FAR) calculator
Floor area ratio — plot ratio in the UK and Gulf, FSI in India — is the single number that caps how much you can build on a site. It is gross floor area divided by plot area. Enter the site and the permitted ratio to see both what you have designed and what the zoning allows.
floor area ratio calculator
- Floor area ratio
- 3
- Site coverage
- 50%
- Maximum permitted GFA
- 4,500m²
- Remaining allowance
- 0m²
Formula
FAR = gross floor area ÷ plot area · coverage = footprint ÷ plot areaWhat counts as gross floor area varies by jurisdiction — basements, plant rooms, balconies and parking are often excluded. Always read the local definition before trusting a ratio.
Worked examples
| Input | Result |
|---|---|
| 4500 m² GFA on a 1500 m² plot | FAR 3.0 — at the limit in most mid-rise zones |
| Same GFA on 3000 m² | FAR 1.5 — typical suburban office allowance |
| 750 m² footprint on 1500 m² | 50% site coverage |
Questions
Is FAR the same as plot ratio and FSI?
Yes — floor area ratio (US), plot ratio (UK, UAE, Australia) and floor space index (India) all describe gross floor area divided by plot area. FSI is sometimes quoted as a percentage.
Does FAR limit building height?
Only indirectly. FAR caps total area; height comes from FAR combined with the coverage limit and setbacks. A low coverage limit with a high FAR forces a tower; the reverse forces a podium.
Which areas are excluded from GFA?
Commonly basements, plant, refuse and lift cores, and sometimes balconies and parking. The exclusions are worth 10–20% of a scheme, so model them as separate area schemes in Revit rather than one lump figure.
Precisa de um especialista certificado em CAD/BIM para alterar este ficheiro?
TaskBider drafters, detailers and BIM coordinators work remotely and every listing shows the pay. Typical published range for this work: $18–$45/hr.
Related tools
Popular CAD conversions
Related AEC calculators
File version help
Top freelance CAD & BIM engineers
- AutoCAD specialistspublished pay
- Revit specialistspublished pay
- Civil 3D specialistspublished pay
- Tekla Structures specialistspublished pay
- Navisworks specialistspublished pay
- ArchiCAD specialistspublished pay
- SketchUp specialistspublished pay
- SolidWorks specialistspublished pay
- 3ds Max specialistspublished pay