Construction Contract Payment Schedule Calculator
ANA›Life Services Authority›National Calculator Authority›Construction Contract Payment Schedule Calculator
.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }
Construction Contract Payment Schedule Calculator
Calculate milestone-based payment schedules for construction contracts including retainage withholding, progress payments, and final payment amounts.
Total Contract Value ($)
Retainage Percentage (%)
Mobilization Payment (%)
Number of Progress Milestones
Substantial Completion Payment (%)
Contract Duration (months)
Calculate Payment Schedule
function conCalc() { var contractValue = parseFloat(document.getElementById('con-contract-value').value); var retainagePct = parseFloat(document.getElementById('con-retainage').value); var mobilizationPct = parseFloat(document.getElementById('con-mobilization').value); var numMilestones = parseInt(document.getElementById('con-milestones').value); var substantialPct = parseFloat(document.getElementById('con-substantial-completion').value); var duration = parseInt(document.getElementById('con-contract-duration').value);
// Input validation if (isNaN(contractValue) || contractValue 50) { document.getElementById('con-result').innerHTML = 'Retainage must be between 0% and 50%.
'; return; } if (isNaN(mobilizationPct) || mobilizationPct 30) { document.getElementById('con-result').innerHTML = 'Mobilization payment must be between 0% and 30%.
'; return; } if (isNaN(numMilestones) || numMilestones 12) { document.getElementById('con-result').innerHTML = 'Number of milestones must be between 1 and 12.
'; return; } if (isNaN(substantialPct) || substantialPct 20) { document.getElementById('con-result').innerHTML = 'Substantial completion payment must be between 0% and 20%.
'; return; } if (isNaN(duration) || duration 120) { document.getElementById('con-result').innerHTML = 'Contract duration must be between 1 and 120 months.
'; return; }
// Validate total allocated percentages // Mobilization + substantial completion + final (retainage release) must leave room for progress payments // Final payment = retainage release at project closeout // Progress payments cover remaining percentage after mobilization and substantial completion var reservedPct = mobilizationPct + substantialPct; if (reservedPct >= 100) { document.getElementById('con-result').innerHTML = 'Mobilization + Substantial Completion percentages cannot equal or exceed 100%. Please reduce these values.
'; return; }
// Core formulas: // Retainage withheld per progress payment = Progress Payment Gross * (retainagePct / 100) // Net progress payment = Gross Progress Payment * (1 - retainagePct / 100) // Progress payment gross = contractValue * (progressPct / 100) // Remaining percentage for progress payments = 100 - mobilizationPct - substantialPct // Each milestone progress pct = remainingPct / numMilestones // Final payment (retainage release) = total retainage withheld across all payments // Total retainage = contractValue * (retainagePct / 100) * (1 - mobilizationPct/100 - substantialPct/100) // Note: retainage is typically only withheld from progress payments, not mobilization or substantial completion
var remainingPct = 100 - mobilizationPct - substantialPct; var eachMilestonePct = remainingPct / numMilestones;
// Dollar amounts var mobilizationGross = contractValue * (mobilizationPct / 100); var substantialGross = contractValue * (substantialPct / 100); var eachMilestoneGross = contractValue * (eachMilestonePct / 100);
// Retainage is withheld from progress milestone payments only (common industry practice) var retainagePerMilestone = eachMilestoneGross * (retainagePct / 100); var netPerMilestone = eachMilestoneGross - retainagePerMilestone; var totalRetainageWithheld = retainagePerMilestone * numMilestones;
// Substantial completion net (retainage sometimes withheld here too - the calculator applies it) var retainageSubstantial = substantialGross * (retainagePct / 100); var netSubstantial = substantialGross - retainageSubstantial; totalRetainageWithheld += retainageSubstantial;
// Final payment = release of all retainage var finalPayment = totalRetainageWithheld;
// Total check var totalPaid = mobilizationGross + (netPerMilestone * numMilestones) + netSubstantial + finalPayment;
// Month intervals var progressInterval = Math.floor(duration / (numMilestones + 2));
var fmt = function(n) { return '$' + n.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ','); }; var fmtPct = function(n) { return n.toFixed(2) + '%'; };
// Build schedule table var rows = ''; var cumulative = 0;
// Mobilization row cumulative += mobilizationGross; rows += '1MobilizationMonth 1' + fmtPct(mobilizationPct) + '' + fmt(mobilizationGross) + '$0.00' + fmt(mobilizationGross) + '' + fmt(cumulative) + '';
var cumulativeNet = mobilizationGross;
// Progress milestone rows for (var i = 1; i duration - 1) month = duration - 1; var completionPct = mobilizationPct + (eachMilestonePct * i); cumulative += eachMilestoneGross; cumulativeNet += netPerMilestone; rows += '' + (i + 1) + 'Progress Payment ' + i + ' (' + fmtPct(completionPct) + ' complete)Month ' + month + '' + fmtPct(eachMilestonePct) + '' + fmt(eachMilestoneGross) + '' + fmt(retainagePerMilestone) + '' + fmt(netPerMilestone) + '' + fmt(cumulativeNet) + ''; }
// Substantial completion row var scMonth = duration - 1; cumulative += substantialGross; cumulativeNet += netSubstantial; rows += '' + (numMilestones + 2) + 'Substantial CompletionMonth ' + scMonth + '' + fmtPct(substantialPct) + '' + fmt(substantialGross) + '' + fmt(retainageSubstantial) + '' + fmt(netSubstantial) + '' + fmt(cumulativeNet) + '';
// Final payment / retainage release cumulativeNet += finalPayment; rows += '' + (numMilestones + 3) + 'Final Payment (Retainage Release)Month ' + duration + '—' + fmt(finalPayment) + '$0.00' + fmt(finalPayment) + '' + fmt(cumulativeNet) + '';
var html = '### Payment Schedule Summary '; html += ''; html += 'Total Contract Value' + fmt(contractValue) + ''; html += 'Total Retainage Withheld' + fmt(totalRetainageWithheld) + ''; html += 'Mobilization Payment' + fmt(mobilizationGross) + ''; html += 'Net Per Progress Payment' + fmt(netPerMilestone) + ''; html += 'Substantial Completion (Net)' + fmt(netSubstantial) + ''; html += 'Final Retainage Release' + fmt(finalPayment) + ''; html += '';
html += ''; html += ''; html += '#MilestoneTiming% of ContractGross AmountRetainage WithheldNet PaymentCumulative Net'; html += '' + rows + ''; html += 'Totals' + fmt(contractValue) + '' + fmt(totalRetainageWithheld) + '' + fmt(totalPaid) + '' + fmt(cumulativeNet) + ''; html += '';
document.getElementById('con-result').innerHTML = html; }
#### Formulas Used
Mobilization Payment: Mobilization ($) = Contract Value × (Mobilization % ÷ 100)
Progress Payment Allocation: Remaining % = 100% − Mobilization % − Substantial Completion % Each Milestone % = Remaining % ÷ Number of Milestones Gross Milestone Payment = Contract Value × (Each Milestone % ÷ 100)
Retainage Withholding: Retainage per Payment = Gross Payment × (Retainage % ÷ 100) Net Payment = Gross Payment × (1 − Retainage % ÷ 100)
Substantial Completion: Substantial Completion ($) = Contract Value × (Substantial Completion % ÷ 100) Net Substantial = Substantial Gross × (1 − Retainage % ÷ 100)
Final Payment (Retainage Release): Final Payment = Σ All Retainage Withheld = (Retainage per Milestone × Number of Milestones) + Retainage on Substantial Completion
Verification: Total Paid = Mobilization + (Net per Milestone × Milestones) + Net Substantial + Final Payment = Contract Value ✓
#### Assumptions & References
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