Triangle Calculator
Solve any triangle from three sides, two sides and an angle, or two angles and a side. Get area, perimeter, angles and heights.
Enter three side lengths to solve the triangle.
Triangle Calculator on True Calculator gives you an instant, accurate answer with no sign-up and no app install. Solve any triangle from three sides, two sides and an angle, or two angles and a side. Get area, perimeter, angles and heights. Every result shows the formula and a worked example so you can verify the calculation yourself, and all values are computed in your own browser — your numbers never leave your device.
Popular uses: triangle calculator · triangle area calculator · triangle solver
Last updated: August 2026
How We Calculate
This calculator uses standard mathematical formulas verified by our team. All calculations are performed instantly in your browser using JavaScript — no data is sent to any server. The formulas used are industry-standard and match those used by banks, financial institutions and health organizations.
For financial calculators, we use RBI-approved formulas and regularly updated bank rates. For health calculators, we use WHO-recommended formulas and medical standards. All rates and standards are sourced from official government and regulatory websites.
Frequently Asked Questions
What is the SSS method?
SSS (Side-Side-Side) uses all three sides. The calculator uses law of cosines for angles and Heron's formula for area.
What is the SAS method?
SAS (Side-Angle-Side) uses two sides and the included angle. The law of cosines finds the third side.
How is triangle area calculated?
From three sides: Heron's formula. From two sides and angle: ½ × a × b × sin(C).
You might also need
Related calculators from other categories
Date
Age Calculator
Find your exact age in years, months and days from your date of birth — plus the weekday you were born on. Free and works offline.
Date
Date Difference Calculator
Count the exact number of days, weeks, months and business days between two dates. Perfect for deadlines, leave planning and projects.
Time
Time Duration Calculator
Calculate hours and minutes between two times, across midnight if needed. Ideal for shifts, travel time and event planning.
Health & Fitness
BMI Calculator
Calculate your Body Mass Index instantly and see your WHO weight category — underweight, normal, overweight or obese. Free for men and women.