Inputs
Results
Profile preview (not to scale). Horizontal = run; vertical = drop.
Formulas Used
- Grade (%) = (rise ÷ run) × 100
- Angle (rad) = atan(rise ÷ run); Angle (°) = Angle (rad) × 180/π
- Ratio (1 in N) where N = run ÷ rise = 100 ÷ Grade(%)
- Given Grade and Run: rise = run × Grade(%) ÷ 100
- Given Grade and Slope Length: rise = slopeLen × sin(Angle); run = slopeLen × cos(Angle)
- Conversions: Grade(%) = tan(Angle) × 100
How to Use
- Choose a Mode for what you need to solve.
- Set Units, enter Length, Drop/Rise, or Slope values.
- Select Length type: horizontal Run or surface Slope length.
- Optionally enter a Start Elevation and choose direction.
- Adjust drainage and grade limits to flag potential issues.
- Press Compute; export results to CSV or PDF if needed.
Example Data
| # | Length (run) | Slope (%) | Drop | Angle (°) | Ratio (1:N) |
|---|---|---|---|---|---|
| 1 | 20 | 2 | 0.4 | 1.146 | 50 |
| 2 | 40 | 5 | 2 | 2.862 | 20 |
| 3 | 60 | 10 | 6 | 5.710 | 10 |
Values auto-switch between ft/m when the unit selector changes.
FAQs
Run is the horizontal projection. Slope length is measured along the driveway surface.
Many projects aim for at least 2% for surface drainage. Adjust the “Min drainage slope” to suit your codes and conditions.
Yes. Angle, percent grade, and “1 in N” ratio are linked. Editing any one updates the others automatically.
The calculator flags grades above your “Comfortable” and “Absolute” thresholds so you can lengthen the driveway or reduce rise.
Yes. Switch units any time. Labels and example data update automatically for consistency.
Use the buttons to export a CSV or generate a PDF report containing inputs, results, and the example table.
Design Data & Reference
Typical Driveway Slope Guidelines
| Use | Recommended Slope (%) | Notes |
|---|---|---|
| Minimum for drainage | 1–2 | Helps avoid standing water on hard surfaces. |
| Comfortable daily access | 5–8 | Most passenger vehicles climb without scraping. |
| Short steep approaches | 10–12 | May require transition ramps to prevent bottoming. |
| Snow/ice regions | ≤ 8 | Lower slopes improve traction and stopping. |
Required Run for Common Target Slopes (based on current drop)
Enter a drop and press Compute; this table updates using your current units.
| Target Slope (%) | Required Run | Required Slope Length |
|---|---|---|
| 2 | — | — |
| 5 | — | — |
| 8 | — | — |
| 10 | — | — |
| 12 | — | — |
Quick Conversion Chart
| Grade (%) | Angle (°) | Ratio (1:N) | Drop per 10 ft | Drop per 3 m |
|---|
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