Gutter Slope and Pitch Calculator
ANA›Life Services Authority›National Calculator Authority›Gutter Slope and Pitch 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; } }
Gutter Slope and Pitch Calculator
Calculate the required drop, slope ratio, and angle for proper gutter drainage. A minimum slope of 1/16 inch per foot (0.52%) is recommended for effective water flow.
Gutter Length (feet)
Slope Input Method
Slope Ratio (inches per foot) Known Drop (inches) Slope Percentage (%)
Slope Ratio (inches per foot)
Recommended: 0.0625 to 0.5 inches per foot
Total Drop (inches)
Slope Percentage (%)
Calculate
function gutToggleInputs() { var type = document.getElementById('gut-slope-type').value; document.getElementById('gut-ratio-group').style.display = (type === 'ratio') ? '' : 'none'; document.getElementById('gut-drop-group').style.display = (type === 'drop') ? '' : 'none'; document.getElementById('gut-percent-group').style.display = (type === 'percent') ? '' : 'none'; document.getElementById('gut-result').style.display = 'none'; }
function gutCalc() { var resultDiv = document.getElementById('gut-result'); resultDiv.style.display = 'block';
var length = parseFloat(document.getElementById('gut-length').value); var type = document.getElementById('gut-slope-type').value;
// --- Validation --- if (isNaN(length) || length 0.5) { warnings.push('⚠️ Slope exceeds 1/2 inch per foot. Water may flow too fast and overshoot the downspout.'); } if (totalDropInches > 3) { warnings.push('⚠️ Total drop exceeds 3 inches. Consider splitting the gutter run with a center outlet or two downspouts.'); }
- var warningHtml = warnings.length > 0
- ? '' + warnings.join('') + ''
- '';
- var dropDisplay = dropFeet > 0
- ? dropFeet + ' ft ' + dropRemIn.toFixed(3) + ' in'
- totalDropInches.toFixed(3) + ' in';
resultDiv.className = 'calc-result calc-success'; resultDiv.innerHTML = '### Results ' + '' + 'Gutter Length' + length.toFixed(2) + ' ft' + 'Total Drop' + dropDisplay + '' + 'Slope Ratio' + slopeInchesPerFoot.toFixed(4) + ' in/ft' + 'Slope Percentage' + slopePercent.toFixed(4) + '%' + 'Slope Angle' + angleDeg.toFixed(4) + '°' + 'Rise : Run1 : ' + riseRunX.toFixed(2) + '' + '' + warningHtml; }
#### Formulas Used
Total Drop (inches): Drop = Slope (in/ft) × Length (ft)
Slope Ratio (inches per foot): Slope (in/ft) = Total Drop (in) ÷ Length (ft)
Slope Percentage: Slope (%) = [Total Drop (in) ÷ (Length (ft) × 12)] × 100
Slope Angle (degrees): θ = arctan[Total Drop (in) ÷ (Length (ft) × 12)]
Rise : Run Ratio: Run per 1 unit Rise = (Length (ft) × 12) ÷ Total Drop (in)
#### Assumptions & References
- The recommended minimum gutter slope is 1/16 inch per foot (0.0625 in/ft), equivalent to approximately 0.52%, to ensure adequate drainage without standing water.
- The commonly recommended optimal slope is 1/4 to 1/2 inch per foot (0.25–0.5 in/ft) for most residential applications.
- Slopes exceeding 1/2 inch per foot may cause water to overshoot the downspout during heavy rain.
- For gutter runs longer than 40 feet, it is advisable to slope from the center toward two downspouts at each end, or use a larger gutter profile.
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