What is this calculator?
Find perimeter and area from three side lengths.
What can you use it for?
Use it when solving an exercise, checking a result, or working with the particular quantities shown in this form. Find perimeter and area from three side lengths.
How to use it
- Enter side a.
- Enter side b.
- Enter side c.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
Area = √[s(s−a)(s−b)(s−c)], where s = (a+b+c)/2
Heron’s formula uses three positive side lengths. Each pair of sides must sum to more than the remaining side.
Worked example
Side a: 3, Side b: 4, Side c: 5. The result is 6 (triangle area).
Assumptions and limits
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.
Frequently asked questions
What inputs does the Triangle Calculator need?
Use side a, side b, side c. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Triangle Calculator?
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.