Triangle Perimeter Calculator
Calculate the perimeter of a triangle from three side lengths. This page also validates whether the side lengths form a valid triangle and classifies the triangle by side type.
Formula:
Perimeter = a + b + c
| Metric | Value |
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Privacy: calculations run locally in your browser. No inputs are stored or transmitted.
How it works
This calculator adds the three sides to get the perimeter. It also checks whether the side lengths satisfy the triangle inequality.
A valid triangle must satisfy:
a + b > c,
a + c > b,
b + c > a
Examples
- 3, 4, 5 → perimeter = 12
- 5, 5, 5 → equilateral triangle
- 5, 5, 8 → isosceles triangle
FAQ
- What is triangle perimeter?
Triangle perimeter is the total length around the triangle, equal to the sum of all three side lengths.
- What formula is used?
This page uses perimeter = a + b + c.
- Why does the calculator validate side lengths?
A valid triangle must satisfy the triangle inequality: each side must be less than the sum of the other two sides.
- Can this calculator classify the triangle?
Yes. It labels the triangle as equilateral, isosceles, or scalene based on the side lengths.
- Are calculations stored?
No. Everything runs locally in your browser.