RightSizeTools Practical sizing calculators
Geometry Basics

Pythagorean Theorem Calculator

Use this when you know the two legs of a right triangle and need the diagonal/hypotenuse.

Last updated: August 2026

Unit system Switch between U.S. customary and metric units. Your choice is remembered on other calculators.

Known square sides

Enter the two sides that meet at the square 90° corner.

Visual guide

Which measurement goes where?

Enter the two legs that meet at the 90° corner. The diagonal side is the hypotenuse.

ft
ft

Buying and sizing notes

How to use this estimate

What this includes

  • The required inputs shown on this page
  • common planning assumptions
  • optional advanced adjustments where provided

What it does not include

  • site-specific professional design
  • local code approval
  • manufacturer-specific requirements
  • installation quality

Common mistakes

  • Leaving a required input at the default when your situation is different
  • ignoring product labels or ratings
  • treating the estimate as an exact final answer

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