Does Triangle Calculator upload my file or text to Tool-You servers?

No. Triangle Calculator runs in this browser tab. Files stay on the device. Limit note: All sides > 0. Degenerate (a+b=c) is rejected. Units are yours.

Should I use Rectangle Calculator instead of Triangle Calculator?

Use Triangle Calculator when you need Area and perimeter from three sides. Use Rectangle Calculator when you need Area, perimeter, and diagonal of a rectangle. They share a category (Calculate) but not the same job.

What are the limits of Triangle Calculator?

All sides > 0. Degenerate (a+b=c) is rejected. Units are yours. Also: Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.

Triangle Calculator

Area and perimeter from three sides.

Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.

What Triangle Calculator does

Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.

Triangle Calculator sits in the Calculate group on purpose. It is not Rectangle Calculator (Area, perimeter, and diagonal of a rectangle.) and not Circle Calculator (Area from radius, diameter, or circumference.). Choose this page when you need Area and perimeter from three sides. If you stretch Triangle Calculator into a neighbor’s job, the result will look wrong even though the site chrome looks the same.

How to use Triangle Calculator

Confirm you need Triangle Calculator, not Rectangle Calculator (Area, perimeter, and diagonal of a rectangle.). Address: /triangle.
Enter the numbers or dates Triangle Calculator uses. Area and perimeter from three sides.
Read the result as Triangle Calculator defines it — not as Circle Calculator (Area from radius, diameter, or circumference.). Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.
Triangle Calculator is an estimate in the browser, not professional advice. All sides > 0. Degenerate (a+b=c) is rejected. Units are yours.
Need a different formula? Try Circle Calculator (Area from radius, diameter, or circumference.) instead of stretching Triangle Calculator.

When not to use Triangle Calculator

Skip Triangle Calculator when a neighbor tool matches better — start with Rectangle Calculator or Circle Calculator — or when the description already warns the job will fail. In the tool’s own words: Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.

Questions about Triangle Calculator

What does Triangle Calculator do that other Calculate pages on this site do not?: Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD. Short version: Area and perimeter from three sides.
Does Triangle Calculator upload my file or text to Tool-You servers?: No. Triangle Calculator runs in this browser tab. Files stay on the device. Limit note: All sides > 0. Degenerate (a+b=c) is rejected. Units are yours.
Should I use Rectangle Calculator instead of Triangle Calculator?: Use Triangle Calculator when you need Area and perimeter from three sides. Use Rectangle Calculator when you need Area, perimeter, and diagonal of a rectangle. They share a category (Calculate) but not the same job.
What are the limits of Triangle Calculator?: All sides > 0. Degenerate (a+b=c) is rejected. Units are yours. Also: Heron's formula. Sides must form a triangle (strict inequality). Not a right-triangle-only tool and not CAD.