ZONING
Lot coverage calculator
Lot coverage is the building footprint divided by the lot area, expressed as a percentage. Most residential districts cap it, and that cap is usually what decides whether a house plan fits the lot.
THE MATH
How it's calculated
Coverage % = building footprint ÷ lot area × 100. Maximum footprint = lot area × coverage limit.
WORKED EXAMPLE
Given: A 2,400 sq ft footprint on an 8,000 sq ft lot, with a 35% cap
Result: 2,400 ÷ 8,000 = 30% coverage, and the 35% cap allows up to 2,800 sq ft of footprint
QUESTIONS
Lot coverage calculator questions
What counts toward the footprint?
Usually the ground-floor area under roof measured to the outside of the walls, plus the attached garage and covered porches. Some ordinances add decks, patios and accessory buildings. Read the definition in the local code, because it varies by city.
Is lot coverage the same as floor area ratio?
No. Coverage measures the footprint against the lot and counts one story. Floor area ratio measures total floor area against the lot and counts every story, so a two-story house can hit an FAR cap while sitting at 30% coverage.
Is impervious coverage a separate limit?
Often. Impervious coverage adds driveways, walkways and patios and is capped separately for stormwater reasons. A plan can pass building coverage and still fail impervious coverage.
Do setbacks change the answer?
Setbacks decide where the footprint may go, coverage decides how large it may be. On a narrow lot the setbacks often bind first, leaving buildable area well below the coverage cap.
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