Maths - Rectangles

Introduction:

This page allows you to calculate every dimension of a Rectangle, if you know enough dimensions already. The actual shape that you are interested in can be any physical object whatsoever, possibly a section of lawn in a garden, or any other DIY task.
Click on any of the links at the top of the page to reveal (or hide) more information about this calculator.

Caveats:

If you are reading this paragraph, then you probably don't have JavaScript installed/enabled on your computer.
At this point in time the calculators on this site are entirely dependent on JavaScript. Given enough time and money it is hoped to develop a version in the future which will be able to operate independently. Since JavaScript runs on your own computer, rather than on this server, it has been possible to set up this site much more quickly than if a server-side language was used, and it is possible to serve far more pages with the available bandwidth.
If you think that you can assist with this project in any way, then please visit the Support section and leave a message.

Definitions:

Rectangle

A two-dimensional object with four sides, of which two pairs are parallel. Opposite sides therefore have the same length, and all corners are right angles (90 degrees.)

Square

A special kind of rectangle where all four sides have an equal length. All of the formulae on this page can also be applied to squares.

Length l / Width w

The distance measured along a single edge of the rectangle. In this context which one is considered Length and which one the Width is entirely irrelevant.

Diagonal d

The distance between either of the opposite corners of the rectangle, eg from top-right to bottom-left.

Circumferance c

The distance measured once around all edges of the rectangle.

Area a

The area enclosed by the rectangle.

Definitions of all Quadrilateral (shapes with four sides):

Squares

All four sides are equal length, and all angles are right angles. Both pairs of opposite sides are parallel. Special case of a rectangle, i.e. all squares are rectangles.

Rectangles

Opposite sides have equal lengths, and all angles are right angles. Both pairs of opposite sides are parallel.

Parallelograms

A two-dimensional object with two pairs of parallel sides. Opposite sides are parallel to each other, and equal in length. No angles are right angles.

Rhombus'

All four sides are equal, but no angles are right angles. Opposite sides are parallel to each other. Special case of a parallelogram.

Kites

Adjacent sides have the same length, opposite angles at the sides are equal, angles at top and bottom are not equal to each other. No more than three angles may be right angles, but often none are.

Trapeziums

Top and bottom are parallel, but different lengths. Opposite sides are the same length as each other, but not parallel. Top two angles are equal to each other, but different from bottom two angles, which are also identical to each other.

Formulae:

• c = (2 * l) + (2 * w)
• a = l * w
• d² = l² + w²

Instructions

1. Fill in as many boxes as you can with the values that you know
2. Choose the correct units for all 'input' fields, or leave as 'Units' if not required
3. Choose the correct units for any output fields that you require
4. Click the 'CalcResult' button below the input fields
5. The value of the blank fields will be calculated
6. A 'Results Area' will be displayed below.
7. All known values will be shown. (Values for which insufficient information was given will also be identified.)
8. To do further calculations simply change any values in the input fields and click the 'CalcResult' button again. (Press the 'Clear Form' button if you want to empty all of the input fields.)
9. Press the 'Clear Results' button if you wish to discard the first results, otherwise further calculations will be added into the same area.
10. Click the 'CalcResult' button again
11. Click the 'Print Results' button to display all current results in a new, printable window.