What does the Triangle Calculator work out?

Area and perimeter from three sides. It is one of the Math tools on Mondo Knows.

How is the Triangle Calculator calculated?

The maths is short enough to check by hand: Heron's formula: A = sqrt(s(s-a)(s-b)(s-c)).

Do I need to sign up, and is my data stored?

No sign-up, and nothing you type is sent anywhere. The calculation runs in your own browser, so the figures stay on your device and the page works offline once loaded.

Mondo Knows Tools

Triangle Calculator

Area and perimeter from three sides. Use the free triangle calculator below to get an instant answer, with the formula shown so you can check the maths and trust the result. Free, private, and no sign-up.

Side a

Side b

Side c

Mondo says

Area

14.696938

Perimeter18

Angle A44.42 deg

Angle B57.12 deg

Angle C78.46 deg

The formula

Heron's formula: A = sqrt(s(s-a)(s-b)(s-c))

Triangle Calculator: common questions

What does the Triangle Calculator work out?: Area and perimeter from three sides. It is one of the Math tools on Mondo Knows.
How is the Triangle Calculator calculated?: The maths is short enough to check by hand: Heron's formula: A = sqrt(s(s-a)(s-b)(s-c)).
Do I need to sign up, and is my data stored?: No sign-up, and nothing you type is sent anywhere. The calculation runs in your own browser, so the figures stay on your device and the page works offline once loaded.

Mondo also knows

Right Triangle CalculatorEvery side and angle of a right triangle.➗ Math Area CalculatorArea of the common shapes.➗ Math Volume CalculatorVolume of the common solids.➗ Math Z-Score CalculatorHow many standard deviations a value sits from the mean.➗ Math

Estimates for general guidance only. This is not financial, medical or legal advice. Everything runs in your browser and nothing you type is stored.