Geometry
Triangle area
- where
- area (m²)
- base (m)
- perpendicular height (m)
Explain this equation
Gives the area of a triangle from its base and perpendicular height. Typical uses are gable ends, triangular infill panels and the sloping part of a stair string wall.
b is any one side taken as the base. h is the height measured square to that base, up to the opposite corner. A is the area in m².
Any triangle is exactly half of a rectangle b wide and h high, so A = bh/2. That holds whatever the shape of the triangle, provided h is truly perpendicular to b.
A gable 4 m wide and 3 m high is 6 m². Doubling either the base or the height doubles the area.
Watch out: h is not the length of a sloping side. Using the rake length instead of the vertical height overstates the area.
Calculate a triangle using its base and perpendicular height.
Enter your values to see the result.
Good to know
The height must be at right angles to the base, not the sloping side.
Sources
- Geometry / arithmetic
This is a calculation aid, not a structural design or compliance certificate. Every default is an example, not a specification for your project.