Math
Rectangle
Find area and perimeter from two sides.
Calculators / Math / Rectangle diagonal and angle
Rectangle diagonal and angle calculator
Calculate a rectangle’s diagonal and its angle from the horizontal width.
On this page
Diagonal length5
Diagonal angle above width36.87degrees
Calculator controls
How to calculate
Calculate a rectangle’s diagonal and its angle from the horizontal width.
Diagonal length =
sqrt(width^2+height^2)Diagonal angle above width =
atan(height/width)*180/pi degreesWorked example
- Rectangle width: 4
- Rectangle height: 3
- Diagonal length: 5
- Diagonal angle above width: 36.87 degrees
Assumptions and limits
Both side lengths use the same unit. The angle is measured above the width edge of an ideal rectangle.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Calculate a rectangle’s diagonal and its angle from the horizontal width. The diagonal is the hypotenuse of a right triangle. A 4-by-3 rectangle gives a diagonal of 5.
When this tool is useful
The diagonal is the hypotenuse of a right triangle. A 4-by-3 rectangle gives a diagonal of 5.
Understanding your inputs
| Input | Example |
|---|---|
Rectangle width width | 4 |
Rectangle height height | 3 |
Frequently asked questions
What assumptions should I check?
Both side lengths use the same unit. The angle is measured above the width edge of an ideal rectangle.
How can I check the result?
Start with the labelled example. Keep units consistent, calculate without intermediate rounding and change one input at a time. The diagram explains the model; the result table supplies the numerical answer.