Buildable Envelope Calculator

Early planning and zoning screening. Estimates the rectangular buildable envelope from lot dimensions, setbacks, and lot coverage. Results update as you type.

Data stays on your device. Nothing is sent to a server.
1. Lot dimensions

Enter the overall dimensions of a rectangular lot in metres.

Width is measured along the street frontage. Depth is measured perpendicular to the street.

2. Required setbacks

Enter the minimum required setbacks in metres. Street side is assumed at the front of the lot.

3. Maximum lot coverage
Lot coverage is a hard cap on building footprint, independent of the setback envelope. A building must comply with both limits.

Enter the maximum lot coverage permitted under the applicable zone.

As a percentage of total lot area.
Formulas used

Buildable width = lot width − left setback − right setback

Buildable depth = lot depth − front setback − rear setback

Envelope area = buildable width × buildable depth

Coverage limit = lot area × maximum lot coverage %

Estimated max footprint = lower of envelope area and coverage limit

Effective lot coverage = max footprint ÷ lot area

Summary

Project / Address Lot Lot area (m²) Envelope (m²) Coverage limit (m²) Max footprint (m²) Eff. coverage Controlling limit

No lots added yet. Use Add to summary to capture the current result.

Important. This tool is for early planning screening only. It assumes a rectangular lot and applies setbacks as simple rectangular deductions. It does not account for zoning exceptions, setback averaging, permitted projections, easements, environmental buffers, floodplain requirements, riparian area regulations, access needs, servicing constraints, topography, or survey accuracy. Always confirm requirements against the applicable zoning bylaw, legal survey, title documents, and any professional advice required for the site. No liability is accepted for decisions made based on this tool.