Calculating your diagonal is straightforward once you know the Diagonal of Rectangle formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Diagonal of Rectangle Calculator.
What is Diagonal of Rectangle?
The Diagonal of Rectangle calculation tells you your diagonal from a few simple inputs. The figure you are solving for here is the diagonal.
The Diagonal of Rectangle formula
The core formula is:
Diagonal = √(Length ^ 2 + Width ^ 2)Here is what each input means:
- Length — a number. Example: 3.
- Width — a number. Example: 4.
How to calculate it step by step
- Write down the length (for example, 3).
- Write down the width (for example, 4).
- Apply the formula above to get your diagonal.
- Double-check the result with the Diagonal of Rectangle Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Length | 3 |
| Width | 4 |
| Diagonal | 5.0000 |
With length of 3 and width of 4, the diagonal works out to 5.0000.
Example 2
With length of 6 and width of 4, the diagonal works out to 7.2111.
| Result | Value |
|---|---|
| Diagonal | 7.2111 |
Example 3
With length of 1.5 and width of 4, the diagonal works out to 4.2720.
| Result | Value |
|---|---|
| Diagonal | 4.2720 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Diagonal of Rectangle Calculator does it instantly, for free, with the formula and a worked example built in.
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