Calculator
Fill any two of these: rise, run, length, angle, or grade. If you enter more, values are checked for mismatches.
Example data table
Sample scenarios to see typical outputs.
| Rise (m) | Run (m) | Angle (°) | Grade (%) | Ramp length (m) |
|---|---|---|---|---|
| 0.30 | 3.60 | 4.7636 | 8.3333 | 3.6125 |
| 0.50 | 5.00 | 5.7106 | 10.0000 | 5.0249 |
| 0.80 | 10.00 | 4.5739 | 8.0000 | 10.0319 |
| 1.20 | 12.00 | 5.7106 | 10.0000 | 12.0599 |
| 0.15 | 2.40 | 3.5763 | 6.2500 | 2.4047 |
Formula used
- Angle:
θ = arctan(rise / run) - Grade percent:
grade% = (rise / run) × 100 - Ramp length:
length = √(rise² + run²) - If angle is known:
rise = tan(θ) × run,run = rise / tan(θ) - If length and angle are known:
rise = sin(θ) × length,run = cos(θ) × length - Slope ratio:
1 : (run / rise)
Calculations assume a right triangle where rise and run are perpendicular.
How to use this calculator
- Choose the unit for your distances.
- Enter any two values (rise, run, length, angle, or grade).
- Click Calculate to see results above the form.
- Optionally enable slope guidance warnings for a quick check.
- Use the download buttons to export the last result.
FAQs
1) What is a ramp angle?
It is the incline measured from the horizontal run to the ramp surface. It’s commonly expressed in degrees or radians, and it directly relates to how steep a ramp feels when used.
2) What is grade percent?
Grade percent is the slope written as a percentage: (rise ÷ run) × 100. A higher percent means a steeper ramp for the same horizontal distance.
3) Which inputs should I enter for best accuracy?
Rise and run are usually the most direct measurements. If you only know the ramp surface length, pair it with rise or run to solve the triangle cleanly.
4) Can I enter more than two inputs?
Yes. The calculator computes using a valid pair, then checks extra fields for mismatches. If numbers don’t align, you’ll see a warning to recheck measurements or units.
5) What does the slope ratio mean?
The ratio is shown as 1 : (run/rise). For example, 1 : 12 means 1 unit up for every 12 units forward.
6) Why does my length input get rejected sometimes?
In a right triangle, the ramp length (hypotenuse) must be greater than both rise and run. If it is not, the geometry is impossible, so the calculator asks you to revise inputs.
7) What do the guidance warnings check?
They flag steep grades that may require special design choices. These messages are informational only. Always confirm your design against local rules and project requirements.
8) Do the downloads include my inputs?
Yes. CSV and PDF exports include both the inputs you entered and the computed outputs. Run a new calculation to refresh the saved result used for downloads.