Setback Calculator — Buildable Envelope & Lot Coverage

    Calculate buildable footprint and lot coverage based on lot dimensions and setbacks. Useful for quick site feasibility checks.

    Tips

    • Setbacks can change by zone, lot type (corner lots), and overlays.
    • Easements can further reduce buildable area.
    • Use this as a first-pass feasibility check, then confirm all constraints with local zoning documents.

    Planning tool only — setbacks, easements, and zoning overlays vary widely. Confirm all constraints with the local planning department.

    Example Calculation

    A 100×120 ft lot with 20 ft front/rear setbacks and 10 ft side setbacks leaves an 80×80 ft buildable envelope (6,400 sqft), which is 53.3% lot coverage.

    Setback Example Scenarios

    Lot (ft)Setbacks (ft)Buildable Envelope (ft)
    50×10020/20/5/540×60
    60×12025/25/6/648×70
    80×12020/20/8/864×80
    100×12020/20/10/1080×80

    Frequently Asked Questions

    What is a buildable envelope?

    The portion of a lot where a building can be placed after accounting for required setbacks.

    Does this include height limits or floor area limits?

    No. This calculator only evaluates a 2D footprint based on setbacks.

    What about corner lots?

    Corner lots may have additional street-side setbacks and special rules. Confirm with local zoning.

    Do easements count like setbacks?

    They can function similarly by restricting building placement. Always check title documents and surveys.

    Is lot coverage the same as FAR?

    No. Lot coverage is footprint area; FAR is total floor area across levels.

    Typical Results

    Front setback(typical suburban residential)20–30 ft
    Side setback(typical residential)5–10 ft
    Rear setback(typical residential)15–25 ft

    💡 Verify setbacks with your local planning department — they vary by lot size, zone, and overlay district.

    Common Mistakes

    • •Measuring from the curb or sidewalk instead of the actual property line
    • •Forgetting that accessory structures (sheds, garages) also have setback requirements
    • •Not accounting for easements, which further restrict where you can build

    Related Guides & Tools

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