Inputs
units:
Enter if known, or it will auto-calculate.
1 :
For example, 1:50 ≈ 2%.
Used for along-slope length and elevation change.
to
Typical lawn/yard drainage often 1%–5%. Adjust to your spec.
Results
Percent Grade
—
Angle (°)
—
Ratio (1:X)
—
Along-slope length
—
Elevation change over distance
—
Drainage check
—
Batch Segments
| # | Label | Start Elevation | End Elevation | Horizontal Distance | Units | Rise | Slope % | Angle ° | Ratio 1:X | Within Range? |
|---|
Example Data
Illustrative landscape segments with varied elevations and distances.
| Label | Start Elevation | End Elevation | Horizontal Distance | Units | Computed Slope % |
|---|---|---|---|---|---|
| Lawn to drain | 102.00 | 101.60 | 20 | ft | 2.0 |
| Path segment A | 101.60 | 101.20 | 48 | ft | 0.83 |
| Drive apron | 101.20 | 100.20 | 60 | ft | 1.67 |
| Ramp to entry | 100.20 | 99.20 | 12 | ft | 8.33 |
Formulas Used
- Percent grade:
% = 100 × rise / run, run ≠ 0. - Angle (degrees):
θ = arctan(rise / run) × 180/π. - Ratio:
1 : XwhereX = run / rise(rise ≠ 0). - Along-slope length:
L = √(run² + rise²). - Elevation change over a horizontal distance
d:Δh = d × (% / 100).
How to Use
- Select SI or US units.
- Enter any two values among rise, run, percent, angle, ratio.
- Click Calculate. The tool derives the rest consistently.
- Provide a horizontal distance to project along-slope length and elevation change.
- Set a target drainage range to check compliance.
- Use the Batch Segments table for multiple areas; add rows, then export.
- Download results or tables as CSV or PDF for records.
Guidance values are illustrative; confirm project requirements, codes, and accessibility standards for your site.
Recommended Slopes for Common Features
Guidance ranges; verify project specs, codes, and accessibility standards locally.
| Feature | Typical Slope % | Approx. Ratio (1:X) | Notes |
|---|---|---|---|
| Lawns / turf areas | 1 – 5% | 1:100 – 1:20 | Promotes drainage without erosion; comfortable to walk. |
| Paved patios / walks | 1 – 2% | 1:100 – 1:50 | Sheds water away from structures; comfortable surface. |
| Residential driveways | 1 – 3% | 1:100 – 1:33 | Limits ponding; steeper sections require traction control. |
| Swales / drainage channels | 2 – 4% | 1:50 – 1:25 | Maintains positive flow while minimizing erosion risk. |
| ADA cross‑slope (walks) | ≤ 2% | ≥ 1:50 | Cross‑slope typically limited to two percent for accessibility. |
| ADA ramps (max) | 8.33% | 1:12 | Maximum running slope for ramp segments; landings required. |
Quick Conversions (Percent ↔ Degrees ↔ Ratio)
| Percent % | Degrees (°) | Approx. Ratio (1:X) |
|---|---|---|
| 0.5% | 0.286 | 1:200 |
| 1% | 0.573 | 1:100 |
| 2% | 1.146 | 1:50 |
| 5% | 2.862 | 1:20 |
| 8.33% | 4.760 | 1:12 |
| 10% | 5.710 | 1:10 |
Conversions use θ = arctan(%/100) and X ≈ 100/% for small angles.
Slope Risk & Maintenance Bands
| Band | Interpretation | Typical Actions |
|---|---|---|
| < 1% | Low fall; drainage may be insufficient. | Add crown, regrade, or subsurface drainage as needed. |
| 1% – 5% | Good for lawns and general surfaces. | Maintain smooth grades; direct flow away from structures. |
| 6% – 8% | Steeper; walking comfort reduces. | Consider steps, handrails, or textured surfaces. |
| 9% – 25% | Challenging for maintenance. | Erosion control, terracing, or groundcovers; limit mowing. |
| ≥ 33% (≈ 3:1) | Very steep; mowing hazardous. | Retaining structures or stabilization; specialized groundcovers. |
Values are indicative; verify site constraints, soils, rainfall, and safety needs.