Triangle Calculator
Three-side (SSS) solver uses Heron’s formula for area and the cosine rule for angles.
Inputs and units
- Side a: Enter your value in the format and unit shown.
- Side b: Enter your value in the format and unit shown.
- Side c: Enter your value in the format and unit shown.
- Dimension unit: Choose Metres, Centimetres, Millimetres, Feet, Inches.
Calculation method
Three-side (SSS) solver uses Heron’s formula for area and the cosine rule for angles.
Worked example
The example values are: Side a = 3; Side b = 4; Side c = 5; Dimension unit = m
- Perimeter (m): 12
- Area (m²): 6
- Angle A (degrees): 36.8698976458
- Angle B (degrees): 53.1301023542
- Angle C (degrees): 90
Assumptions and limitations
Enter all three sides in the same unit.
Using your result
Select Calculate after changing inputs. Copy result copies the displayed output; Download result saves a text file. Reset returns the form to its example inputs. Calculations run in your browser.
Triangle Calculator FAQs
What method does this calculator use?
Three-side (SSS) solver uses Heron’s formula for area and the cosine rule for angles.
What should I check before using the result?
Enter all three sides in the same unit.