Hypotenuse and Adjacent Side Calculator

By: Patrick Myers Patrick Myers is the CEO and Founder of Calculator Academy. He has over eight years of experience developing online calculators and holds a B.S. in Mechanical Engineering. His work focuses on formula implementation, calculator accuracy, unit conversions, and creating practical tools that are easy to use.

Last Updated: July 3, 2026
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This calculator was built with Calculator Academy’s community calculator studio with AI assistance, and was reviewed by the Calculator Academy team before publication.

About the Hypotenuse and Adjacent Side Calculator

Use this tool to find the base length and sloped length of a right triangle when you know the vertical rise and the base angle. It is helpful for geometry problems, ramps, roof or stair layout sketches, and any situation where the angle is measured upward from the horizontal adjacent side.

How to use this calculator

  1. Enter the rise length in inches.
  2. Enter the angle in degrees, greater than 0 and less than 90.
  3. Review the automatically updated adjacent side and hypotenuse.
  4. Check the slope percent and run per 1 inch of rise if needed.
  5. Use 90 degrees minus your angle if your angle was measured from vertical instead of from the base.

How it works

The calculator treats the rise as the side opposite the entered angle. The entered angle is the acute angle between the adjacent base side and the hypotenuse of a right triangle.

It converts the angle from degrees to radians for the trigonometric functions, then calculates adjacent side = rise ÷ tan(angle). The hypotenuse is calculated as hypotenuse = rise ÷ sin(angle).

The slope percent is tan(angle) × 100, and the run per 1 inch rise is adjacent ÷ rise. Inputs must use a positive rise and an angle greater than 0° and less than 90°.

Example calculation

For a rise of 12 in and an angle of 30°, adjacent = 12 ÷ tan(30°) = 20.78 in. Hypotenuse = 12 ÷ sin(30°) = 24 in. The slope is tan(30°) × 100 = 57.74%, and the run per 1 in rise is 20.78 ÷ 12 = 1.73 in.

Frequently asked questions

What does adjacent side mean in this calculator?

It is the horizontal base side next to the entered angle, not including the hypotenuse.

What if my angle is measured from the vertical rise?

Use 90° minus that angle before entering it, because the calculator expects the angle from the horizontal base to the hypotenuse.

Why must the angle be less than 90 degrees?

A right triangle already has one 90° angle, so the entered acute base angle must be between 0° and 90°.

Are the results in inches?

Yes. Because the rise is entered in inches, the adjacent side and hypotenuse are also returned in inches.