Tree Age Estimator
ANA›Life Services Authority›National Calculator Authority›Tree Age Estimator
.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; } }
Tree Age Estimator
Estimate a tree's approximate age based on its trunk diameter at breast height (DBH) and species growth factor.
Measurement Type
Diameter (DBH) Circumference (CBH)
Trunk Diameter at Breast Height (inches)
Tree Species
Silver Maple (Growth Factor: 3.0) American Elm (Growth Factor: 3.5) Red Oak (Growth Factor: 4.0) Sugar Maple (Growth Factor: 4.5) White Oak (Growth Factor: 5.0) Dogwood (Growth Factor: 5.5) Redbud (Growth Factor: 6.0) Ironwood (Growth Factor: 7.0) Custom Growth Factor
Custom Growth Factor
Growth factor = average years of growth per inch of diameter. Typically ranges from 2 (fast) to 7 (slow).
Estimate Age
function treUpdateLabel() { var type = document.getElementById('tre-measurement-type').value; var label = document.getElementById('tre-trunk-label'); var input = document.getElementById('tre-trunk-value'); if (type === 'circumference') { label.textContent = 'Trunk Circumference at Breast Height (inches)'; input.placeholder = 'e.g. 56.5'; } else { label.textContent = 'Trunk Diameter at Breast Height (inches)'; input.placeholder = 'e.g. 18'; } }
document.getElementById('tre-species').addEventListener('change', function() { var customField = document.getElementById('tre-custom-gf-field'); customField.style.display = (this.value === 'custom') ? 'block' : 'none'; });
function treCalc() { var resultDiv = document.getElementById('tre-result'); resultDiv.className = 'calc-result'; resultDiv.innerHTML = '';
var measureType = document.getElementById('tre-measurement-type').value; var trunkVal = parseFloat(document.getElementById('tre-trunk-value').value); var speciesVal = document.getElementById('tre-species').value;
// Validate trunk measurement if (isNaN(trunkVal) || trunkVal 300) { resultDiv.className = 'calc-result calc-error'; resultDiv.innerHTML = '⚠ Diameter seems unrealistically large. Please check your input.'; return; }
// Determine growth factor var growthFactor; if (speciesVal === 'custom') { growthFactor = parseFloat(document.getElementById('tre-custom-gf').value); if (isNaN(growthFactor) || growthFactor 20) { resultDiv.className = 'calc-result calc-error'; resultDiv.innerHTML = '⚠ Growth factor seems unrealistically high. Typical range is 2–7.'; return; } } else { growthFactor = parseFloat(speciesVal); }
// Core formula: Age = DBH (inches) × Growth Factor var estimatedAge = dbh * growthFactor;
// Confidence range ±20% var lowerBound = Math.round(estimatedAge * 0.80); var upperBound = Math.round(estimatedAge * 1.20); var ageRounded = Math.round(estimatedAge);
// Circumference display var cbh = (measureType === 'circumference') ? trunkVal : (dbh * Math.PI); var dbhDisplay = dbh.toFixed(2); var cbhDisplay = cbh.toFixed(2);
resultDiv.className = 'calc-result calc-success'; resultDiv.innerHTML = '### Estimated Tree Age ' + 'Approximate Age: ' + ageRounded + ' years
' + 'Likely Range: ' + lowerBound + ' – ' + upperBound + ' years (±20%)
' + '' + 'Inputs Used:
' + '' + '' + '' + '' + '' + 'Note: This is an estimate. Actual age may vary based on soil, climate, and growing conditions.
'; }
#### Formula
Estimated Age (years) = DBH (inches) × Growth Factor
Where:
- DBH = Diameter at Breast Height, measured at 4.5 feet (1.37 m) above ground
- Growth Factor = Species-specific average years of growth per inch of diameter
- If circumference (CBH) is provided: DBH = CBH ÷ π
Example: A Red Oak (Growth Factor = 4.0) with a DBH of 18 inches: Age ≈ 18 × 4.0 = 72 years (range: 58–86 years)
#### Assumptions & References
- Reference: Bernatzky, A. (1978). Tree Ecology and Preservation; ISA Best Management Practices.
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