Inputs
Switching units will convert all current area values.
m²
Net site area used for FSR calculations.
If provided, we’ll assess compliance and margin.
Gross Floor Area Components
| Component / Level | Area | |
|---|---|---|
| Total GFA | 0 m² |
Your inputs save automatically on this device.
Results
Enter values to see FSR and compliance.
Floor Space Ratio
—
Total GFA
— m²
Allowed GFA
— m²
Margin
— m²
Example Data Table
Click a row to populate inputs.
| Scenario | Site area | Allowed FSR | Built GFA | FSR |
|---|---|---|---|---|
| Urban infill lot | 2,200 m² | 2.5 | 5,100 m² | 2.32 |
| Midrise mixed-use | 3,600 m² | 3.0 | 9,800 m² | 2.72 |
| Suburban parcel | 4,800 m² | 1.0 | 4,100 m² | 0.85 |
Formula Used
FSR = Total Gross Floor Area ÷ Site Area. Values are dimensionally consistent and unitless. Allowed floor area (if any) equals Allowed FSR × Site Area. Margin equals Allowed Floor Area − Built Floor Area.
Always reference your local by-law definitions for “gross floor area,” “net site area,” and exclusions (e.g., parking, mechanical, balconies). Jurisdictions vary on what's counted.
How to Use This Calculator
- Select your unit system. Enter the Site area and, if applicable, the Allowed FSR.
- Add rows under Gross Floor Area Components for each building, wing, or level. Enter areas; totals update automatically.
- Review FSR, Allowed GFA, and Margin in the results panel. The status chip shows compliance.
- Click Download CSV for a spreadsheet export, or Export PDF for a formatted summary.
- Use Load example or click an Example Data Table row to trial typical scenarios.
- Use Copy shareable link to generate a permalink embedding your current inputs.
FSR vs Storeys at Assumed Coverage
Approximate relationship: FSR ≈ Site Coverage × Storeys. Table shows FSR for common coverages across storey counts.
| Storeys | 40% coverage | 50% coverage | 60% coverage |
|---|
Allowed GFA Cheat Sheet
For the current site area, allowed floor area at typical FSR limits. Enter site area above to populate values.
| FSR | Allowed Floor Area |
|---|
FAQs
Floor Space Ratio (FSR) is the ratio of total gross floor area to the net site area. It is dimensionless and used to regulate development intensity.
It depends on your jurisdiction. Some exclude structured parking, mechanical rooms, or balconies. Always check the local by-law definitions and exclusions.
Yes. Site coverage compares ground-level building footprint to site area. FSR compares total floor area across all storeys to site area.
Adjust the site area and the calculator will recompute FSR, allowed floor area, and compliance automatically. Use the shareable link to communicate updates.
Results are computed using straightforward arithmetic on your inputs. Precision depends on your data quality and rounding requirements in your jurisdiction.
Yes. Use local autosave, copy a shareable permalink, download a CSV for spreadsheets, or generate a PDF summary for quick review and approvals.