Inputs
Used for rise, run, and slope length.
Decimal places for results.
Enter any two of rise, run, percent grade, or angle. The calculator will compute the rest.
ft
ft
%
°
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Results
Rise: – ft
Run: – ft
Slope length: – ft
Percent grade: – %
Angle: – deg
Ratio: rise:run = –
One-in-N: 1 in –
Example Data Table
Start with these examples or add your own scenarios below.
| # | Timestamp | Rise | Run | Percent | Angle (°) | Slope length | Ratio | 1 in N | Notes |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Preset | 0.5 ft | 6 ft | 8.333% | 4.76° | 6.02 ft | 1:12 | 12.00 | Typical accessibility ramp section |
| 2 | Preset | 3 ft | 50 ft | 6.000% | 3.43° | 50.09 ft | 3:50 | 16.67 | Common roadway grade |
Formulas Used
\( \text{percent grade} = 100 \times \frac{\text{rise}}{\text{run}} \)\( \theta = \arctan\!\left( \frac{\text{rise}}{\text{run}} \right) \; [\text{degrees}] \)\( \text{slope length} = \sqrt{\text{rise}^2 + \text{run}^2} \)\( \text{one-in-}N = \frac{\text{run}}{\text{rise}} \)(for rise > 0)
How to calculate stopping distance grade incline?
Stopping distance combines reaction distance and braking distance. A grade changes effective deceleration. Define downhill grade as positive (increases stopping distance), uphill as negative (reduces stopping distance).
Equations (small angles / highway use)
v_{\mathrm{m/s}} = v_{\mathrm{km/h}} \times \frac{1000}{3600} = v_{\mathrm{mph}} \times 0.44704G = \frac{\text{grade}\%}{100}(use+Gfor downhill,+Gmagnitude)a_{\mathrm{downhill}} \approx g \, (\,\mu - G\,)a_{\mathrm{uphill}} \approx g \, (\,\mu + G\,)s_r = v \, t_r(reaction distance)s_b = \dfrac{v^2}{2 a}(braking distance)s_{\mathrm{total}} = s_r + s_b
Here g = 9.81 \ \mathrm{m/s^2}, \mu is tire–road friction (e.g., dry ~0.7, wet ~0.4). If \mu \le G on a downhill, braking distance diverges (insufficient friction).
Worked example
Given: v = 60 km/h, t_r = 1.5 s, \mu = 0.7, grade = ±6%.
| Scenario | a (m/s²) | s_r (m) | s_b (m) | s_total (m) |
|---|---|---|---|---|
| Downhill 6% | 6.278 | 25.00 | 22.12 | 47.12 |
| Uphill 6% | 7.456 | 25.00 | 18.63 | 43.63 |
Tip: Use this calculator to find grade from rise/run or angle, then plug G into the formulas above.
How to Use This Calculator
- Select the measurement unit and desired precision.
- Provide any two of: Rise, Run, Percent grade, or Angle.
- Click Calculate. The remaining values are computed instantly.
- Click Add to Table to log a scenario for export.
- Use Download CSV for spreadsheets or Download PDF for reports.
- Use Share URL to copy a link with your current inputs.