| Scenario | Unit | Plot area | Main footprint | Additional footprint | Limit | Coverage ratio | Status |
|---|---|---|---|---|---|---|---|
| Urban residential | m² | 500 | 180 | 20 | 60% | 40.00% | PASS |
| Compact infill | ft² | 4,000 | 2,100 | 150 | 55% | 56.25% | FAIL |
| Light commercial | yd² | 900 | 330 | 45 | 50% | 41.67% | PASS |
- Select a unit and use it for every area entry.
- Enter plot area from survey drawings or site plans.
- Enter footprints using covered ground-level areas.
- Add a limit if you want a pass/fail check.
- Calculate, then export CSV or PDF for records.
Coverage ratio and approval workflows
Plot coverage is commonly reviewed during concept planning, zoning checks, and permit submissions. Many residential rules cap ground coverage near 35–60%, while light commercial parcels can vary widely by corridor and use. This calculator standardizes inputs across units and produces a traceable pass/fail indicator when you enter a limit. Use it for quick feasibility, then confirm the official limit.
What counts toward building footprint
Coverage typically uses the horizontal projection of roofed or covered areas at ground level. Main structures, attached garages, covered verandas, and service annexes often count. Items like canopies, balconies, or detached shade structures may be treated differently. Enter separate footprints so the report shows how each area contributes to total coverage. Measure from scaled plans or surveys, and keep assumptions consistent.
Open area and site performance
The remaining open area helps evaluate usable outdoor space, light access, and landscape percentages. Open area also influences stormwater performance because larger permeable zones can reduce runoff. If you enable the optional paved-area input, the tool reports an impervious estimate to support early drainage discussions and surface planning. Pair these outputs with setbacks and access requirements to balance buildable area and site circulation overall.
Interpreting results for design decisions
When coverage is close to the limit, small layout changes can restore compliance: reduce a porch depth, convert a covered bay to an open terrace, or relocate an enclosed stair. If the footprint exceeds plot area, the tool flags the issue immediately. Use the precision selector to match survey rounding and drawing conventions. Run scenarios to see how extensions affect compliance.
Documentation and stakeholder reporting
A clear calculation record improves coordination between architects, engineers, contractors, and reviewers. The exported CSV supports internal cost and scope tracking, while the PDF provides a compact summary for submissions and meeting notes. Keep the project label consistent so iterations remain easy to compare. Record what was included in footprint totals for reviewers and share the same basis with project consultants.
FAQs
1) Is plot coverage the same as floor area ratio?
No. Coverage uses the ground-level footprint. Floor area ratio compares total floor area across stories to plot area. A multi‑storey building can have low coverage and high floor area ratio.
2) Which unit should I use for best accuracy?
Use the unit that matches your drawings and measurements. The tool converts internally, so accuracy depends on correct inputs, not the selected unit. Keep all area fields in the same unit.
3) Why does the calculator show an impervious estimate?
Many projects must consider runoff and paved surfaces. The impervious estimate adds driveway/paved area to the building footprint, then reports the percent of the plot that may shed water more quickly.
4) What should I enter as “additional footprint”?
Add any covered ground-level areas outside the main building footprint, such as a garage extension, covered patio, guard room, or store. If unsure, record it separately and verify requirements locally.
5) The result says FAIL. What can I adjust first?
Start with optional covered elements: porches, canopies, verandas, and secondary covered bays. Small reductions often bring coverage below the limit. Confirm whether any elements can be excluded by local rules.
6) Can I use the exports in permit packages?
Exports are helpful as supporting calculations, but they do not replace signed drawings or official forms. Attach the PDF as a summary and reference the source dimensions from your survey and plans.