Triangle Calculator
Calculate triangle area from base and height, or perimeter from three sides.
How this calculator works
How to use this calculator
Choose whether you want to calculate triangle area or perimeter. For area, enter base and height. For perimeter, enter all three side lengths.
Formula used
Triangle Area = 1/2 × base × height. Triangle Perimeter = side a + side b + side c.
Example calculation
A triangle with base 10 and height 6 has area 30 square units. A triangle with sides 3, 4, and 5 has perimeter 12 units.
What the result means
Area measures the space inside the triangle. Perimeter measures the total distance around the triangle.
Frequently asked questions
What is the triangle inequality?
For three sides to form a triangle, the sum of any two sides must be greater than the third side.
Can this calculate angles?
No. This calculator focuses on basic area and perimeter.
What units should I use?
Use consistent units. Perimeter uses length units, while area uses square units.