Free Lot Coverage Ratio Calculator
Calculate the lot coverage ratio by comparing the building footprint and impervious surfaces to the total lot area, and check compliance with zoning maximum coverage limits.
Building Coverage Ratio
25.0%
Building Coverage Ratio vs Total Lot Area (sq ft)
Lot Coverage Ratio
Lot coverage measures how much of a parcel is covered by buildings and impervious surfaces. Zoning codes use coverage limits to control density, manage stormwater, and preserve neighborhood character.
Building Coverage Ratio
Building Coverage = Building Footprint / Lot Area x 100
This measures only the building footprint (first floor area), not total floor area.
Impervious Coverage Ratio
Impervious Coverage = Total Impervious Surfaces / Lot Area x 100
Includes buildings, driveways, patios, walkways, and any surface that prevents water absorption.
Why Coverage Matters
Example Calculation
10,000 sq ft lot, 2,500 sq ft building footprint, 800 sq ft driveway/patio, 200 sq ft other impervious, 35% max building coverage, 60% max impervious.
- 01Building coverage: 2,500 / 10,000 = 25.0%
- 02Total impervious: 2,500 + 800 + 200 = 3,500 sq ft
- 03Impervious coverage: 3,500 / 10,000 = 35.0%
- 04Remaining building capacity: 3,500 - 2,500 = 1,000 sq ft
- 05Remaining impervious: 6,000 - 3,500 = 2,500 sq ft
- 06Open space: 10,000 - 3,500 = 6,500 sq ft (65.0%)