Triangle area calculator (base and height)
Enter a base and the perpendicular height to it to get the area of any triangle, right, acute or obtuse.
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How to use it
- Enter base, height and length unit.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Area = ½ × base × height, where the height is the perpendicular distance from the opposite vertex to the base line.
Example
Inputs: Base = 10, Height = 5, Length unit = Centimeters (cm). Result: Triangle area: 25 cm².
Limits and caveats
- The height must be perpendicular to the base, not the length of a slanted side.
- If you only know the three sides, use the Heron's formula calculator.
Questions about this tool
What is the formula for the area of a triangle?
Area is half the base times the height. A triangle with base 10 and height 5 has an area of 25.
Where is the height of an obtuse triangle?
It can fall outside the triangle, drawn from the vertex to the extended base line. The formula stays the same.
Can any side be the base?
Yes, as long as you use the height perpendicular to that side. The area comes out the same.