Diagonal & Hypotenuse Calc

Diagonal Calculator – Geometry makes it fast to compute diagonals for squares, rectangles, triangles, and parallelograms. It runs offline and supports multiple units—feet, inches, cm, mm, and meters—perfect for on-site work, classrooms, and DIY projects.

Designed for engineers, carpenters, students, and designers, this tool uses standard geometry formulas and the Pythagorean theorem to deliver instant, accurate results from two known values. It also includes a TV/screen diagonal calculator and a dedicated feet-and-inches input mode to streamline construction and planning tasks.