How to calculate slope in percent, degrees and rise
Slope can be expressed as percent, degrees, rise per metre or a 1:n ratio. The Slope calculator converts between these forms without treating them as equivalent numbers.
Slope (%) = rise ÷ horizontal distance × 100. A 10 cm drop over 5 m is 2%. This also means 2 cm of rise or fall per horizontal metre.
A 5% slope corresponds to arctan(0.05), about 2.86°, not 5°. This distinction matters when drawings and product instructions use different conventions.
For 2% over 7.5 m, the rise is 7.5 × 0.02 = 0.15 m, or 15 cm. The corresponding angle is only about 1.15°.
The percentage formula uses horizontal distance. A tape laid directly on a steep ramp measures the inclined length, which is a different value. Identify horizontal, vertical and inclined dimensions before calculating.
The 1:n form expresses the same geometry differently: 1:20 equals 5%. Inclined length can be obtained with Pythagoras from horizontal distance and rise.
The calculator converts geometry; it does not decide the required regulatory or technical slope for a roof, ramp, drain or terrace. Obtain the target value from the relevant project specification.
For an outdoor aggregate layer use the Gravel calculator; for a concrete element use the Concrete calculator.
Collection
6 / 17
Calculate a weighted average, distinguish assessment and subject weights, find the mark you need next and work out attendance separately.
Learn how to calculate actual working time, handle breaks, split shifts, midnight crossings and decimal hours.
Understand the difference between weight, fat mass, lean mass and muscle mass, and why the scale tells only part of the story.