Cement Pack ProConcrete quantity tools

Site preparation

Rectangle diagonal

Calculate the corner-to-corner distance of a rectangle from its length and width.

Enter your measurements

Example values are prefilled. Replace them with your measurements before using the estimate. JavaScript is required to calculate.

ft

Enter a value greater than zero.

ft

Enter a value greater than zero.

How it is calculated

Expected diagonal = √(length² + width²).

Keep the full result when using it in another calculation. Results show up to three decimal places; very small positive results use scientific notation (for example, 1e-6). No extra material for waste is added.

Enter the planned side lengths

Enter the two perpendicular side lengths of the rectangle you intend to lay out. The calculator uses the Pythagorean theorem to find the distance between opposite corners: the square root of length squared plus width squared.

Keep both side measurements in the same unit. The diagonal result uses that same unit, so feet in produce feet out.

Use the diagonal as a comparison length

A planned rectangle 12 ft long and 16 ft wide has an expected diagonal of 20 ft. This is the target distance implied by those entered sides, not a measurement of the layout in the field.

Comparing a measured diagonal with this result can identify a difference, but the calculator does not verify the field measurements, corner angles, elevations, or the full layout. Follow the project’s layout and checking procedure.

Before you use the result

  • The formula applies to a flat rectangle with right-angle corners.
  • One diagonal measurement, or even two equal diagonals, does not by itself confirm side lengths, square corners, elevations, or the complete layout.
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