Commercial Zoning Setback and Lot Coverage Calculator

ANA›Life Services Authority›National Calculator Authority›Commercial Zoning Setback and Lot Coverage Calculator

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Commercial Zoning Setback and Lot Coverage Calculator

Calculate required setbacks (front, rear, and side yards) and the maximum allowable building footprint area based on your lot dimensions, zoning district, and local coverage limits.

Lot Width (ft)

Lot Depth (ft)

Required Front Setback (ft)

Required Rear Setback (ft)

Required Left Side Setback (ft)

Required Right Side Setback (ft)

Maximum Lot Coverage Allowed (%)

Proposed Building Footprint (sq ft) (optional)

Calculate

function comCalc() { var resultDiv = document.getElementById('com-result'); resultDiv.style.display = 'none'; resultDiv.innerHTML = '';

// --- Parse inputs --- var lotWidth = parseFloat(document.getElementById('com-lot-width').value); var lotDepth = parseFloat(document.getElementById('com-lot-depth').value); var frontSetback = parseFloat(document.getElementById('com-front-setback').value); var rearSetback = parseFloat(document.getElementById('com-rear-setback').value); var leftSetback = parseFloat(document.getElementById('com-side-setback-left').value); var rightSetback = parseFloat(document.getElementById('com-side-setback-right').value); var maxCoveragePct = parseFloat(document.getElementById('com-max-coverage').value); var proposedRaw = document.getElementById('com-proposed-footprint').value.trim(); var proposedFootprint = proposedRaw === '' ? null : parseFloat(proposedRaw);

// --- Validation --- var errors = [];

if (isNaN(lotWidth) || lotWidth 100) errors.push('Maximum Lot Coverage must be between 1 and 100 percent.'); if (proposedFootprint !== null && (isNaN(proposedFootprint) || proposedFootprint = lotDepth) errors.push('Front + Rear setbacks equal or exceed Lot Depth — no buildable depth remains.'); } if (!isNaN(lotWidth) && !isNaN(leftSetback) && !isNaN(rightSetback)) { if (leftSetback + rightSetback >= lotWidth) errors.push('Left + Right setbacks equal or exceed Lot Width — no buildable width remains.'); }

if (errors.length > 0) { resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; resultDiv.style.display = 'block'; return; }

// --- Core Calculations ---

// 1. Gross Lot Area var lotArea = lotWidth * lotDepth;

// 2. Buildable Envelope Dimensions (after setbacks) var buildableWidth = lotWidth - leftSetback - rightSetback; var buildableDepth = lotDepth - frontSetback - rearSetback;

// 3. Maximum Buildable Envelope Area (geometric limit from setbacks) var envelopeArea = buildableWidth * buildableDepth;

// 4. Maximum Allowable Footprint from Coverage Limit // Max Footprint (coverage) = Lot Area × (Max Coverage % / 100) var maxFootprintByCoverage = lotArea * (maxCoveragePct / 100);

// 5. Effective Maximum Footprint = min(envelope area, coverage-limited area) var effectiveMaxFootprint = Math.min(envelopeArea, maxFootprintByCoverage);

// 6. Actual Coverage % if proposed footprint given
var actualCoveragePct = null;
var coverageCompliant = null;
var envelopeCompliant = null;
if (proposedFootprint !== null) {
actualCoveragePct = (proposedFootprint / lotArea) * 100;
coverageCompliant = actualCoveragePct ✓ ' + yesText + ''
'✗ ' + noText + ''; }

// --- Build Output --- var html = '### Results '; html += 'ParameterValue'; html += 'Gross Lot Area' + fmt(lotArea) + ' sq ft (' + fmt(lotArea/43560) + ' acres)'; html += 'Buildable Width (after side setbacks)' + fmt(buildableWidth) + ' ft'; html += 'Buildable Depth (after front & rear setbacks)' + fmt(buildableDepth) + ' ft'; html += 'Max Buildable Envelope Area (setbacks only)' + fmt(envelopeArea) + ' sq ft'; html += 'Max Footprint by Coverage Limit (' + fmt(maxCoveragePct,1) + '%)' + fmt(maxFootprintByCoverage) + ' sq ft'; html += 'Effective Max Allowable Footprint' + fmt(effectiveMaxFootprint) + ' sq ft';

var limitingFactor = (envelopeArea Binding Constraint' + limitingFactor + '';

if (proposedFootprint !== null) { html += 'Proposed Building Footprint' + fmt(proposedFootprint) + ' sq ft'; html += 'Actual Lot Coverage' + fmt(actualCoveragePct) + '%'; html += 'Coverage Compliance' + badge(coverageCompliant, 'Compliant', 'Exceeds ' + fmt(maxCoveragePct,1) + '% limit') + ''; html += 'Setback Envelope Compliance' + badge(envelopeCompliant, 'Fits within envelope', 'Exceeds buildable envelope') + ''; var overallOk = coverageCompliant && envelopeCompliant; html += 'Overall Compliance' + badge(overallOk, 'COMPLIANT', 'NON-COMPLIANT') + ''; }

html += ''; resultDiv.innerHTML = html; resultDiv.style.display = 'block'; }

#### Formulas Used

Gross Lot Area Lot Area = Lot Width × Lot Depth

Buildable Envelope Dimensions Buildable Width = Lot Width − Left Side Setback − Right Side Setback Buildable Depth = Lot Depth − Front Setback − Rear Setback

Setback Envelope Area Envelope Area = Buildable Width × Buildable Depth

Maximum Footprint by Coverage Limit Max Footprint (coverage) = Lot Area × (Max Coverage % ÷ 100)

Effective Maximum Allowable Footprint Effective Max = min(Envelope Area, Max Footprint by Coverage)

Actual Lot Coverage (if proposed footprint entered) Actual Coverage % = (Proposed Footprint ÷ Lot Area) × 100

#### Assumptions & References

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References

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