Triangle area calculator
Calculate the area of a triangle from a base and its perpendicular height. Both measurements must use the same length unit.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Base | Enter base using the definition in the method and example. |
| Perpendicular height | Enter perpendicular height using the definition in the method and example. |
Understanding your result
Read Triangle area (square units) in the units and model stated on this page. The formula A = base × height ÷ 2 defines the relationship; measurement accuracy and model applicability are separate from numerical precision.
Common mistakes
- Using a different mathematical definition or operation than the one stated by this tool.
Check your calculation
- Use the worked example as a known reference case, then change one input at a time and check the direction and units of the response.
Calculation checks, sources and review limits
How much area does a triangle cover?
Enter a base and the perpendicular distance to the opposite vertex. The area is half their product.
Common uses
- Calculate the area of a triangular surface.
- Solve an area problem when base and height are known.
How it works
Multiply base by the perpendicular height and divide by two. The height is the shortest distance from the opposite vertex to the line containing the base. A sloping side usually is not the perpendicular height.
Worked example
A base of 8 and a perpendicular height of 5 give an area of 8 × 5 ÷ 2 = 20 square units.