Diagonal of a Square Calculator


Diagonal of a Square Calculator

Get ready, math enthusiasts! We’re venturing into the thrilling world of squares, but not just any part of the square – we’re digging into the most exciting, underappreciated part of the square… the diagonal!

To calculate the diagonal (d) of a square, you’ll need this handy, dandy formula:

d = a * sqrt(2)

where a is the length of a side of the square, and sqrt(2) is the square root of 2. Pretty straightforward, right? Let’s get down to business!

Types of Diagonal Calculations

Type Range Interpretation
Small less than 1 inch Trivial
Medium 1-10 inches Moderate
Large more than 10 inches Substantial

Example Calculations

Name Side Length Diagonal Length Calculation Process
Tiny Tim 0.5 inches 0.71 inches 0.5 * sqrt(2)
Average Joe 5 inches 7.07 inches 5 * sqrt(2)
Big Ben 20 inches 28.28 inches 20 * sqrt(2)

Calculation Methods

Method Advantages Disadvantages Accuracy Level
Direct Calculation Fast, Easy Requires square root of 2 High
Using Pythagoras’ Theorem Universally Known Requires more steps High

Evolution of Diagonal Calculations

Time Period Calculation Method
Ancient Geometric Methods
Modern Algebraic Formulas

Limitations of Accuracy

  1. Measurement Error: The accuracy of the diagonal depends on the accuracy of the side length measurement.
  2. Rounding Error: The square root of 2 is an irrational number, so any calculations involving it will have some rounding error.


Alternative Method Pros Cons
Using a Ruler to Measure Diagonal Quick and Easy Not Very Accurate


  1. What is the formula for calculating the diagonal of a square? The formula is d = a * sqrt(2) where d is the diagonal and a is the side length.
  2. What is the diagonal of a square with side length of 5 inches? The diagonal is calculated as d = 5 * sqrt(2), which is approximately 7.07 inches.
  3. What does ‘sqrt’ mean in the formula? ‘Sqrt’ stands for ‘square root’. It’s a mathematical operation that, in this case, is applied to the number 2.
  4. Why do we multiply by sqrt(2) to find the diagonal? This comes from the Pythagorean theorem. In a square, the diagonal forms a right triangle with two sides of the square, and the square of the diagonal is equal to the sum of the squares of the other two sides.
  5. Is the diagonal of a square always longer than the side? Yes, the diagonal of a square is always longer than the side. It’s approximately 1.41 times the length of the side.
  6. Can the diagonal of a square be smaller than the side? No, the diagonal of a square is always longer than the side.
  7. How accurate is the diagonal calculation? The accuracy of the calculation depends on the accuracy of the measurement of the side length and on the precision of the square root of 2 used in the calculation.
  8. What are the limitations of diagonal calculations? The limitations include measurement error of the side length and rounding error due to the irrational nature of the square root of 2.
  9. Can I measure the diagonal with a ruler? Yes, you can measure the diagonal with a ruler, but it’s usually less accurate than calculation.
  10. What if my square is not perfect? If your square is not perfect, then the formula d = a * sqrt(2) may not give an accurate estimate of the diagonal.


  1. U.S. Metric Association For more information on metric measurements and conversions.