Diagonal Calculator

Diagonal Length: 0.00
Perimeter: 0.00
Area: 0.00
Width: 16 Height: 9 Diagonal: 18.36
Calculation History

Diagonal Calculator: Easily Find the Diagonal of Any Rectangle

Want to calculate the diagonal of a rectangle quickly and accurately? Whether you're working on a school project, designing furniture, or measuring a screen size, a Diagonal Calculator can save you time and eliminate errors. Instead of struggling with manual calculations or complex formulas, this digital tool gives you instant, precise results with just a few inputs.

Let's explore what a Diagonal Calculator is, how it works, and why you should use one.

What is a Diagonal Calculator?

A Diagonal Calculator is an easy-to-use online tool that helps you calculate the diagonal length of a rectangle using the width and height. It is especially useful for:

  • ✅ Finding screen sizes (TVs, monitors, smartphones)
  • ✅ Designing objects like tables, boards, or windows
  • ✅ Construction and architectural measurements
  • ✅ Geometry homework and academic projects

Just enter the rectangle's width and height, and the calculator will give you the exact diagonal in seconds.

How Does a Diagonal Calculator Work?

The Diagonal Calculator uses the Pythagorean Theorem to compute the diagonal:

Diagonal (d) = √(width² + height²)

Where:

  • Width = One side of the rectangle
  • Height = The adjacent side
  • Diagonal = The straight line from one corner to the opposite corner

You don't have to do the math yourself—just input the numbers, and let the calculator do the rest!

How to Use a Diagonal Calculator?

It's super simple and takes less than a minute:

  1. 1️⃣ Enter the Width – Input the horizontal length of the rectangle (e.g., 10 cm)
  2. 2️⃣ Enter the Height – Input the vertical length of the rectangle (e.g., 5 cm)
  3. 3️⃣ Click 'Calculate' – Instantly get the diagonal length (e.g., 11.18 cm)

This gives you the exact distance between opposite corners of the rectangle.

Example Calculation

Let's say you have a rectangle that is 10 cm wide and 5 cm high.

Using the formula:
Diagonal = √(10² + 5²) = √(100 + 25) = √125 ≈ 11.18 cm

So, the diagonal is 11.18 cm—perfect for precise measurements!

Why Use a Diagonal Calculator?

  • 🔹 Quick & Easy – No formulas, no confusion. Just results.
  • 🔹 Accurate Results – Eliminate errors from manual calculations.
  • 🔹 Compare Dimensions – Try different measurements and instantly see the diagonal.
  • 🔹 Perfect for Multiple Uses – Whether for screens, furniture, or blueprints, it fits all purposes.
  • 🔹 Great for Students & Professionals – Ideal for geometry learners, architects, designers, and engineers.

It's like having a smart assistant for all your measurement needs!

Factors That Affect Diagonal Length

Here are the key factors that influence the diagonal:

  • ✔️ Width and Height – Larger sides mean a longer diagonal
  • ✔️ Units Used – Make sure to use the same unit (cm, inch, mm, etc.) for both width and height
  • ✔️ Precision – For technical work, the more decimal places, the better
  • ✔️ Application – Some designs need exact diagonals, especially in construction and electronics

The Diagonal Calculator lets you play around with these inputs to get just the right result.

FAQs

A Diagonal Calculator is a tool that helps you calculate the length of the diagonal of a rectangle or square using the Pythagorean theorem. You input the length and width, and it calculates the diagonal.
It uses the formula √(length² + width²) to calculate the diagonal of a rectangle or square. Just enter the values for length and width, and the tool does the math instantly.
You need to enter:
  • Length: The length of the rectangle or square.
  • Width: The width of the rectangle or square.
No, this calculator is specifically designed for rectangles and squares. For other shapes like triangles or polygons, different formulas are needed.
Yes, the diagonal length is calculated in the same unit as the input values. If you enter length and width in meters, the result will be in meters.
No, the calculator works directly in your web browser. You don’t need to download or install any software.
Yes, the calculator supports decimal inputs for precise measurements and returns an accurate diagonal length.
Yes, the Diagonal Calculator is completely free to use without any login or registration required.