Rectangle Diagonal
The diagonal is the hypotenuse of a right triangle whose legs are the sides, so Pythagoras gives it. Screen sizes, picture frames and whether something clears a doorway all come down to this figure.
Your numbers
Diagonal
183.58cm
Area
14,400cm²
Perimeter
500cm
Waist-to-chest
1.778
Formula
Diagonal = √(Length ² + Width ²)
The diagonal alone is not enough for moving furniture. Anything with thickness needs room to rotate, so the opening has to be a little wider than the diagonal.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Length (cm)The measurement across, side to side. | 160 | 0 and up |
| Width (cm)The measurement front to back. | 90 | 0 and up |
Step by step
Quick reference table
Results when only Length (cm) changes and everything else stays put.
| Length (cm) | Diagonal (cm) | Area (cm²) | Perimeter (cm) |
|---|---|---|---|
| 80 | 120.42 | 7,200 | 340 |
| 120 | 150 | 10,800 | 420 |
| 160 | 183.58 | 14,400 | 500 |
| 240 | 256.32 | 21,600 | 660 |
| 320 | 332.42 | 28,800 | 820 |
What each result means
| Result | At default values |
|---|---|
| Diagonal (cm)Corner to opposite corner. | 183.58 |
| Area (cm²)The space a shape covers — length squared. | 14,400 |
| Perimeter (cm)The total length around the outside of a shape. | 500 |
| Waist-to-chestWidth over height — the same idea as an aspect ratio. | 1.778 |
Common mistakes
The diagonal alone is not enough for moving furniture. Anything with thickness needs room to rotate, so the opening has to be a little wider than the diagonal.
Glossary
- Length
- The measurement across, side to side.
- Width
- The measurement front to back.
- Diagonal
- Corner to opposite corner.
- Area
- The space a shape covers — length squared.
- Perimeter
- The total length around the outside of a shape.
- Waist-to-chest
- Width over height — the same idea as an aspect ratio.
Frequently asked questions
Q. How is Rectangle Diagonal calculated?
Diagonal = √(Length ² + Width ²) — The diagonal is the hypotenuse of a right triangle whose legs are the sides, so Pythagoras gives it. Screen sizes, picture frames and whether something clears a doorway all come down to this figure.
Q. Can you walk through an example?
With Length 160cm, Width 90cm, the answer is Diagonal 183.58cm.
Q. What do I need to enter?
Enter Length, Width. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Length (cm) moves the answer to Length (cm) 80 → Diagonal (cm) 120.42 and Length (cm) 320 → Diagonal (cm) 332.42. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The diagonal alone is not enough for moving furniture. Anything with thickness needs room to rotate, so the opening has to be a little wider than the diagonal.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.