Triangle Calculator — free
Calculate triangle area, perimeter and angles.
How to use Triangle Calculator
Enter Triangle Measurements
Input your triangle data in the input fields at the top of the calculator. You can enter either three sides (SSS), two sides and an included angle (SAS), or two angles and a side (AAS). Select the calculation type from the dropdown menu labeled 'Select Calculation Type' before entering values.
Input Values in Correct Units
Type numerical values into each field. Use consistent units throughout (all centimeters, all inches, etc.). The calculator accepts decimal values up to 2 decimal places. Ensure all required fields are filled—empty fields will show a red border indicating missing data.
Click Calculate Button
Press the blue 'Calculate' button located below the input fields. The calculator processes your data instantly without page reload. Results appear in the 'Results' section showing area (square units), perimeter (linear units), and all three angles in degrees.
Review and Copy Results
Check the calculated values displayed in the results panel. Click the 'Copy Results' button to copy all calculations to your clipboard. Use the 'Reset' button to clear fields and start a new calculation.