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Geometry

Rectangle Diagonal Calculator

Find the diagonal from a rectangle’s two perpendicular sides.

Use consistent dimensionsArea and volume units explained below
Geometry desk
Geometry desk

Match each dimension to the shape and keep units consistent.

See the method

Set the dimensions

Runs on your device

Your measurement

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter length, width.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

Input reference and sample values

Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.

InputFormat and unitsSample
LengthNumeric value. Unit: m. Must be greater than zero.6
WidthNumeric value. Unit: m. Must be greater than zero.4

Result for these sample inputs

7.21110255 m

Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.

The method, explained

Diagonal = √(length² + width²).

A WORKED EXAMPLE

Using length = 6 m, width = 4 m, the result is 7.21110255 m. Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Use the indicated units consistently. Ideal shapes are assumed; dimensions must describe the same object. Display rounding does not increase measurement precision.

Methodology maintained by ClarityKit. How these tools are built and checked.