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Rectangle Diagonal Calculator

Calculate rectangle diagonal using the Pythagorean theorem d = √(l² + w²).

Author

Dr. Aisha Bello

Math editorial contributor

Nigerian public health specialist with an MPH from Harvard, working on vaccine distribution logistics in West Africa

Reviewed by

Dr. Samuel Okafor

Math content reviewer

Nigerian-Canadian data scientist with a PhD from the University of Toronto, building ML models for early cancer detection

Last updatedFebruary 22, 2026

PublishedFebruary 22, 2026

Table of Contents

  1. Reference values
  2. Calculator
  3. Reference table
  4. FAQs
  5. Methodology and review
  6. Related conversions

5 units Length; 6 units Width =

7.81025 units

Representative value from the Rectangle Diagonal Calculator reference table.

Reference Values

Browse 25 reference values with individual detail pages for quick lookup.

Browse all reference values

Rectangle Diagonal Calculator

Calculate rectangle diagonal using the Pythagorean theorem d = √(l² + w²).

Calculated Result

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Reference Table

Use this complete table for quick lookup and internal linking to specific value pages.

Rectangle Diagonal Calculator Reference
ScenarioDiagonal
1 units Length; 1 units Width1.414214 units
1 units Length; 3 units Width3.162278 units
1 units Length; 6 units Width6.082763 units
1 units Length; 12 units Width12.041595 units
1 units Length; 24 units Width24.020824 units
2 units Length; 1 units Width2.236068 units
2 units Length; 3 units Width3.605551 units
2 units Length; 6 units Width6.324555 units
2 units Length; 12 units Width12.165525 units
2 units Length; 24 units Width24.083189 units
5 units Length; 1 units Width5.09902 units
5 units Length; 3 units Width5.830952 units
5 units Length; 6 units Width7.81025 units
5 units Length; 12 units Width13 units
5 units Length; 24 units Width24.515301 units
10 units Length; 1 units Width10.049876 units
10 units Length; 3 units Width10.440307 units
10 units Length; 6 units Width11.661904 units
10 units Length; 12 units Width15.620499 units
10 units Length; 24 units Width26 units
20 units Length; 1 units Width20.024984 units
20 units Length; 3 units Width20.223748 units
20 units Length; 6 units Width20.880613 units
20 units Length; 12 units Width23.323808 units
20 units Length; 24 units Width31.240999 units

Frequently Asked Questions

Common questions about Rectangle Diagonal Calculator, formulas, and typical use cases.

What does the Rectangle Diagonal Calculator calculator do?

It helps with finding corner-to-corner measurements for rectangular panels and screens.

What formula does the Rectangle Diagonal Calculator calculator use?

Rectangle diagonal = √(length² + width²).

What inputs are valid?

Length and width should be zero or greater. Physical dimensions are typically positive.

When would I use this?

finding corner-to-corner measurements for rectangular panels and screens

Methodology and Review

This page combines a live calculator, precomputed reference values, and FAQ content from the same conversion definition to reduce mismatch between calculator output and lookup tables.

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