Slope Calculator

Slope Calculator – Calculate slope for construction

Slope is a key measurement in many construction projects – from roofs to ramps and inclines. It can be expressed in three different ways: as a percentage, in degrees, or as a ratio, and different contexts use different representations. This calculator converts the slope into all these forms at once.

Three ways to express slope

Percentage indicates the rise relative to the horizontal distance in hundredths – for example, a 10% slope means a rise of 10 centimeters for every meter. Degree angle expresses the same thing as a geometric angle relative to the horizontal plane – this is often used in the context of roof slopes. Ratio (for example, 1:12) indicates how many units of horizontal distance are needed for one unit of rise – this is a common way to express the slope of ramps and inclines, especially in accessibility requirements.

Accessibility slope requirement for ramps

For ramps intended for wheelchair or walker users, the commonly applied recommendation is 1:12, which corresponds to about an 8.3% slope – a steeper ramp is difficult or impossible to use independently with assistive devices. For long ramps, an even gentler slope and intermediate landing areas for resting are often recommended.

Importance of roof slope

The slope of a roof affects both appearance and functionality – a slope that is too gentle can collect snow and water problematically, while a steep roof drains rainwater and snow more effectively but requires more roofing material and can be more challenging to maintain. Different roofing materials (for example, metal roofing vs. felt roofing) have their own recommended slope ranges, which the manufacturer usually specifies.

Practical examples of slope

• Yard drainage: typically, a slope of 1-2% is sufficient to direct rainwater away from the building.
• Deck flooring: typically about a 1-2% slope for water drainage.
• Driveway ramp to garage: usually no more than about 15-20%, to avoid scraping the bottom of the car at a steep point.
• Gentle shed roof: often about 3-15°, while a steeper gable roof can be 30-45° or more.

The exact slope requirement for ramps and inclines varies depending on the intended use and local regulations – always check the current requirements for your project.