ToolPages.slopeCalculator.title
ToolPages.slopeCalculator.description
寸法を入力
図解
2.86° angle
結果
勾配
5.00%
Moderate
Classification guide
What Is Slope Percentage?
Slope percentage (also called percent grade or gradient) measures how steeply a surface rises or falls. It is calculated as:
A 5% slope means the ground rises 5 metres for every 100 metres of horizontal distance. The same value in degrees is approximately 2.86°. This calculator converts instantly between percentage, degrees, and rise:run ratio.
Common Slope References
| Application | Slope % | Angle | Ratio |
|---|---|---|---|
| ADA wheelchair ramp (max) | 8.33% | 4.76° | 1 : 12 |
| Road maximum grade | 12% | 6.84° | 1 : 8.3 |
| Driveway (typical) | 10% | 5.71° | 1 : 10 |
| Agricultural field | 2 – 5% | 1.1 – 2.9° | 1 : 20–50 |
| Roof drainage (min) | 2% | 1.1° | 1 : 50 |
| Terrace farming limit | 20% | 11.3° | 1 : 5 |
Slope Calculator Use Cases
Drainage & Grading
Calculate whether a yard, patio, or roof has sufficient slope to drain water away. Minimum 1-2% grade prevents standing water.
Road & Driveway Design
Verify that a road or driveway grade stays within safe limits. Most road codes limit slopes to 12% and driveways to 15%.
Agricultural Land Assessment
Classify field steepness for erosion risk, equipment suitability, and irrigation planning. Fields above 8% may need contour farming.
Accessibility Compliance
Check ramp slopes against ADA (8.33% max) or building code requirements for accessible routes.
Frequently Asked Questions
What is slope percentage?
Slope percentage is the ratio of vertical rise to horizontal run, multiplied by 100. A 5% slope rises 5 metres for every 100 metres of horizontal distance.
How do I convert slope percentage to degrees?
Use the formula: angle = arctan(slope% ÷ 100). For example, 10% slope = arctan(0.10) = 5.71°. This calculator converts automatically.
What is a 1 in 12 slope in percent?
A 1:12 slope (rise 1, run 12) equals approximately 8.33%. This is the maximum ADA-compliant ramp slope in the United States.
What is a good slope for drainage?
For yards, patios, and walkways, a minimum 1–2% slope is recommended to drain water away from structures. Gutters and pipes need at least 0.5–1% grade.
What slope percentage is considered steep?
Slopes above 10% are steep for most construction. Roads are typically limited to 12% and driveways to 15%. Agricultural land above 20% usually requires terracing.
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