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Slope calculator: %, degrees and 1:n
Enter how much the ground rises and over what distance, and we give you the gradient as a percentage, in degrees and as a ratio, and whether it works for a ramp. Everything is calculated in your browser: nothing is sent.
Conversion table
The most searched gradients as a percentage, in degrees and as a ratio. 100 % is 45°: it rises as much as it advances.
| Percentage | Degrees | Ratio | Typical use |
|---|---|---|---|
| 1 % | 0.6° | 1:100 | Almost flat paving |
| 2 % | 1.1° | 1:50 | Outdoor paving, drainage |
| 5 % | 2.9° | 1:20 | |
| 6 % | 3.4° | 1:16.7 | Long accessible ramp |
| 8 % | 4.6° | 1:12.5 | Accessible ramp < 6 m |
| 10 % | 5.7° | 1:10 | Accessible ramp < 3 m |
| 12 % | 6.8° | 1:8.3 | General-use ramp |
| 15 % | 8.5° | 1:6.7 | |
| 20 % | 11.3° | 1:5 | |
| 25 % | 14° | 1:4 | |
| 33 % | 18.3° | 1:3 | |
| 50 % | 26.6° | 1:2 | |
| 100 % | 45° | 1:1 |
How we calculate
- Gradient as a percentage: rise ÷ horizontal distance × 100. Rising 1 m over 10 m is 10 %.
- Degrees: the angle whose tangent is rise ÷ distance. 10 % is about 5.7°; 100 % is 45°.
- Ratio 1:n: how many horizontal metres there are for each metre of rise. 10 % is 1:10; 50 % is 1:2.
- Length along the slope: the hypotenuse, √(rise² + distance²). It is what the ramp measures on the ground and what gets paved.
What the calculator does not do
The references are those of the Spanish building code for general-use ramps (CTE DB-SUA 1, section 4.3.1). In the garden of a private house they are not always compulsory, but they are a good measure of comfort. The calculator does not check the stability of a bank or a wall: a qualified professional calculates and signs that.
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Frequently asked questions
How do you calculate a slope percentage?
Divide the rise by the horizontal distance and multiply by 100. If the ground rises 2 m over 25 m, the gradient is 2 ÷ 25 × 100 = 8 %.
How many degrees is a 100 % slope?
45°. A 100 % slope rises as much as it advances: 1 m of rise over 1 m horizontally.
What is the maximum gradient for a ramp?
As a reference, the Spanish CTE limits general-use ramps to 12 %. On accessible routes, to 10 % on runs under 3 m, 8 % on runs under 6 m and 6 % otherwise.
What does a 1:20 slope mean?
That for each metre of rise there are 20 horizontal metres. It is 5 %, about 2.9°.