Click here to see information for all quadrilaterals.
For a trapezoid calculator, click here trapezoids.
For a kite calculator, click here kites.
For a rhombus calculator, click here rhombuses.
For a square and rectangle calculator, click here squares.

First, click on one of the choices, enter the data in the appropriate input boxes, then click “CALCULATE”.

If an obtuse angle is input, the program will automatically convert it to an acute angle.

Parallelogram area = (height × AB) or (height × DC)

Lines AC and DB are called diagonals.
Diagonals bisect each other.
Diagonals are not equal.
Diagonals do not bisect the vertex angles.

Line ‘h’ is perpendicular to lines AB & DC and is called the height or altitude.

• BOTH pairs of opposite sides are equal.
AB = DC   and   AD = BC

• BOTH pairs of opposite angles are equal.
∠ A = ∠ C   and   ∠ B = ∠ D

• Adjacent angles are supplementary.
∠ A + ∠ D   =   ∠ D + ∠ C =   ∠ C + ∠ B =   ∠ B + ∠ A = 180°

• Each diagonal forms 2 congruent triangles.
Δ ADC = Δ ABC and Δ DAB = Δ DCB

The default setting is for 5 significant figures but you can change that by inputting another number in the box above.

Answers are displayed in scientific notation and for easier readability, numbers between .001 and 1,000 will be displayed in standard format (with the same number of significant figures.)
The answers should display properly but there are a few browsers that will show no output whatsoever. If so, enter a zero in the box above. This eliminates all formatting but it is better than seeing no output at all.