Preventive Maintenance Schedule Calculator

ANA›Life Services Authority›National Calculator Authority›Preventive Maintenance 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; } }

Preventive Maintenance Schedule Calculator

Calculate maintenance intervals, next service dates, and annual maintenance costs based on equipment usage patterns and service requirements.

Last Service Date

Maintenance Interval Type

Time-Based (Days) Usage-Based (Hours/Miles/Units) Combined (Whichever Comes First)

Time Interval (Days)

Usage Interval (Hours/Miles/Units)

Current Usage Since Last Service

Average Daily Usage (Hours/Miles/Units per Day)

Cost Per Service Session ($)

Estimated Downtime Per Service (Hours)

Equipment Hourly Operating Value ($/hr)

Calculate Maintenance Schedule

(function() { // Set default last service date to today var today = new Date(); var yyyy = today.getFullYear(); var mm = String(today.getMonth() + 1).padStart(2, '0'); var dd = String(today.getDate()).padStart(2, '0'); document.getElementById('pre-last-service').value = yyyy + '-' + mm + '-' + dd;

window.preToggleIntervalType = function() { var type = document.getElementById('pre-interval-type').value; var timeGroup = document.getElementById('pre-time-group'); var usageGroup = document.getElementById('pre-usage-group'); var currentUsageGroup = document.getElementById('pre-current-usage-group'); var dailyUsageGroup = document.getElementById('pre-daily-usage-group');

if (type === 'time') { timeGroup.style.display = ''; usageGroup.style.display = 'none'; currentUsageGroup.style.display = 'none'; dailyUsageGroup.style.display = 'none'; } else if (type === 'usage') { timeGroup.style.display = 'none'; usageGroup.style.display = ''; currentUsageGroup.style.display = ''; dailyUsageGroup.style.display = ''; } else { timeGroup.style.display = ''; usageGroup.style.display = ''; currentUsageGroup.style.display = ''; dailyUsageGroup.style.display = ''; } };

window.preCalc = function() { var errors = [];

var lastServiceStr = document.getElementById('pre-last-service').value; if (!lastServiceStr) errors.push("Please enter the last service date."); var lastServiceDate = new Date(lastServiceStr + 'T00:00:00'); if (isNaN(lastServiceDate.getTime())) errors.push("Invalid last service date.");

var intervalType = document.getElementById('pre-interval-type').value; var timeInterval = parseFloat(document.getElementById('pre-time-interval').value); var usageInterval = parseFloat(document.getElementById('pre-usage-interval').value); var currentUsage = parseFloat(document.getElementById('pre-current-usage').value); var dailyUsage = parseFloat(document.getElementById('pre-daily-usage').value); var serviceCost = parseFloat(document.getElementById('pre-service-cost').value); var downtimeHours = parseFloat(document.getElementById('pre-downtime-hours').value); var hourlyRate = parseFloat(document.getElementById('pre-hourly-rate').value);

if (intervalType === 'time' || intervalType === 'combined') { if (isNaN(timeInterval) || timeInterval 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = '⚠ ' + errors.join('⚠ ') + ''; return; }

var todayDate = new Date(); todayDate.setHours(0, 0, 0, 0); lastServiceDate.setHours(0, 0, 0, 0);

// Days elapsed since last service var msPerDay = 24 * 60 * 60 * 1000; var daysElapsed = Math.floor((todayDate - lastServiceDate) / msPerDay);

var nextServiceDate = null; var daysUntilService = null; var triggerReason = ''; var usageRemaining = null; var daysUntilUsageTrigger = null;

if (intervalType === 'time') { // Next service = last service date + time interval nextServiceDate = new Date(lastServiceDate.getTime() + timeInterval * msPerDay); daysUntilService = Math.floor((nextServiceDate - todayDate) / msPerDay); triggerReason = 'Time interval (' + timeInterval + ' days)';

} else if (intervalType === 'usage') { // Usage remaining = usageInterval - currentUsage usageRemaining = usageInterval - currentUsage; if (usageRemaining = 100 ? '#c0392b' : compliancePct >= 80 ? '#e67e22' : '#27ae60';

var usageRow = ''; if (intervalType !== 'time' && !isNaN(usageRemaining)) { usageRow = 'Usage Remaining Until Service' + usageRemaining.toFixed(1) + ' units'; }

resultDiv.style.display = 'block'; resultDiv.innerHTML = '### Maintenance Schedule Results ' + '' + '⚠ Status: ' + urgency + (isOverdue ? ' — ' + overdueBy + ' day(s) past due' : '') + '' + '' + '' + 'Maintenance Interval Progress' + compliancePct.toFixed(1) + '%' + '' + '' + '' + '' + '' + '' + 'Last Service Date' + lastServiceStr + '' + 'Days Elapsed Since Last Service' + daysElapsed + ' days' + 'Next Service Date' + nextServiceFormatted + '' + 'Days Until Next Service' + (isOverdue ? '' + daysUntilService + ' (overdue)' : daysUntilService + ' days') + '' + usageRow + 'Trigger Reason' + triggerReason + '' + 'Estimated Annual Services' + annualServices.toFixed(2) + ' services/year' + 'Annual Maintenance Cost$' + annualMaintenanceCost.toFixed(2) + '' + 'Annual Downtime Cost$' + annualDowntimeCost.toFixed(2) + '' + 'Total Annual Cost of Maintenance$' + totalAnnualCost.toFixed(2) + '' + 'Average Daily Maintenance Cost$' + costPerDay.toFixed(2) + '/day' + ''; }; })();

#### Formulas Used

Next Service Date (Time-Based): Next Service Date = Last Service Date + Time Interval (days)

Days Until Service (Usage-Based): Usage Remaining = Usage Interval − Current Usage Since Last Service Days Until Service = Usage Remaining ÷ Average Daily Usage

Combined Mode: Next Service = MIN(Time-Based Date, Usage-Based Date)

Annual Services: Time-Based: Annual Services = 365 ÷ Time Interval Usage-Based: Annual Services = (Daily Usage × 365) ÷ Usage Interval Combined: Annual Services = MAX(Time-Based Annual, Usage-Based Annual)

Annual Costs: Annual Maintenance Cost = Annual Services × Cost Per Service Annual Downtime Cost = Annual Services × Downtime Hours × Hourly Operating Value Total Annual Cost = Annual Maintenance Cost + Annual Downtime Cost

Interval Progress: Progress (%) = (Elapsed Days ÷ Time Interval) × 100  |  or  |  (Current Usage ÷ Usage Interval) × 100

#### Assumptions & References

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References

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