Right triangle calculator
Enter any two values — rise, run, diagonal, or angle — and solve for everything else.
in
in
Right triangle
Rise
36″
36.0000″
Run
48″
48.0000″
Diagonal
60″
60.0000″
Angle
36.9°
36.8699°
Pitch
9/12
75.0% grade
Area
864 sq in
6.00 sq ft
How It Works
The right triangle is the foundation of construction math. Every rafter, stair stringer, and slope calculation comes down to the relationship between rise (vertical), run (horizontal), and diagonal (hypotenuse).
Enter any two known values and the calculator solves for everything else using the Pythagorean theorem and basic trigonometry. Results include pitch (rise per 12 inches of run) and grade (rise as a percentage of run) — the two most common ways contractors express slope.
Common Uses
- Finding rafter length from roof pitch and span
- Calculating stair stringer diagonal from rise and run
- Converting between pitch, angle, and grade for slopes
- Squaring foundations using 3-4-5 triangles
These calculators are provided for estimation and educational purposes only. Not a substitute for professional engineering judgment.