Ramp Length Calculator
A 1:12 slope travels 12 cm forward for every 1 cm of rise. The run is the height times that figure, and the board itself is the hypotenuse of the triangle made by rise and run.
Your numbers
Hypotenuse
180.6cm
Run
180cm
Grade (%)
8.33%
Angle (°)
4.76°
What it means
At 1:12 or gentler, this is a slope a wheelchair user can manage unaided.
Formula
Hypotenuse = √(Rise² + (Rise × Slope 1:n)²)
The usual wheelchair standard is 1:12. A 15 cm step needs 180 cm of run, so check the space before you buy.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Rise (cm)How far it climbs, straight up. | 15 | 0 and up |
| Slope 1:nHow far you travel level per 1 of rise — 12 for a 1:12 ramp. | 12 | 0 and up |
Step by step
Quick reference table
Results when only Rise (cm) changes and everything else stays put.
| Rise (cm) | Hypotenuse (cm) | Run (cm) | Grade (%) (%) |
|---|---|---|---|
| 7.5 | 90.3 | 90 | 8.33 |
| 11.3 | 136.1 | 135.6 | 8.33 |
| 15 | 180.6 | 180 | 8.33 |
| 22.5 | 270.9 | 270 | 8.33 |
| 30 | 361.2 | 360 | 8.33 |
What each result means
| Result | At default values |
|---|---|
| Hypotenuse (cm)The longest side of a right triangle, facing the right angle. | 180.6 |
| Run (cm)How far it travels horizontally. | 180 |
| Grade (%) (%)How far you rise over 100 of horizontal run. | 8.33 |
| Angle (°) (°)An angle in degrees; a full turn is 360°. | 4.76 |
Common mistakes
The usual wheelchair standard is 1:12. A 15 cm step needs 180 cm of run, so check the space before you buy.
Glossary
- Rise
- How far it climbs, straight up.
- Slope 1:n
- How far you travel level per 1 of rise — 12 for a 1:12 ramp.
- Hypotenuse
- The longest side of a right triangle, facing the right angle.
- Run
- How far it travels horizontally.
- Grade (%)
- How far you rise over 100 of horizontal run.
- Angle (°)
- An angle in degrees; a full turn is 360°.
Frequently asked questions
Q. How is Ramp Length Calculator calculated?
Hypotenuse = √(Rise² + (Rise × Slope 1:n)²) — A 1:12 slope travels 12 cm forward for every 1 cm of rise. The run is the height times that figure, and the board itself is the hypotenuse of the triangle made by rise and run.
Q. Can you walk through an example?
With Rise 15cm, Slope 1:n 12, the answer is Hypotenuse 180.6cm.
Q. What do I need to enter?
Enter Rise, Slope 1:n. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Rise (cm) moves the answer to Rise (cm) 7.5 → Hypotenuse (cm) 90.3 and Rise (cm) 30 → Hypotenuse (cm) 361.2. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The usual wheelchair standard is 1:12. A 15 cm step needs 180 cm of run, so check the space before you buy.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.