Construction geometry
Rectangle diagonal and perimeter
Find the target diagonal, perimeter and area of an assumed rectangle from two perpendicular side lengths.
Your inputs
Complete the fields for your selected method. Zero means intentionally zero, not unknown. Currency selection labels amounts; it does not convert exchange rates.
How this calculation works
diagonal = sqrt(length² + width²); perimeter = 2 × (length + width); area = length × width
Measurement arithmetic for the stated ideal shape. Verify dimensions and assumptions at the site. No structural sizing, code compliance, safe load, stair approval, accessibility certification or boundary survey is supplied. The sides are assumed perpendicular. A calculated diagonal is a layout target; this tool does not certify that an existing structure is square. Equal diagonals alone do not prove every quadrilateral is a rectangle.
What information do I need?
Use records for the same job, equipment or accounting period. Only the fields for your selected entry method are required. An unknown amount is not zero.
Input definitions and where to find them
- Rectangle length (ft): Measure the stated distance and select its unit. Feet, inches and meters are supported. A perpendicular height is not a sloping length.
- Rectangle width (ft): Measure the stated distance and select its unit. Feet, inches and meters are supported. A perpendicular height is not a sloping length.
Use the Where to find this value controls beside the inputs for available work-it-out helpers. Estimates remain your assumptions; a helper does not verify the source figures.
Worked example
Example amounts use US dollars (USD).
Example answer: Target rectangle diagonal is 20.0000 ft for the illustrative inputs below.
Example inputs
- Rectangle length: 12.00 ft
- Rectangle width: 16.00 ft
- Target rectangle diagonal
- 20.0000 ft
- Rectangle perimeter
- 56.0000 ft
- Rectangle area
- 192.0000 ft²
- Target diagonal in meters
- 6.0960 m
These illustrative values are not recommended rates or industry averages. Replace every example input with your own figures.
Use the result well
Find the target diagonal, perimeter and area of an assumed rectangle from two perpendicular side lengths.
Keep inputs on the same scope and time basis. Calculations retain precision internally; displayed values generally round to two decimal places, with extra precision for very small values and whole-unit rounding where required. Economic comparisons describe your supplied assumptions and do not guarantee future results.
This tool provides business arithmetic. It does not approve engineering designs, establish legal or tax treatment, select equipment or certify safe operating conditions.