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Free Online Quadrilateral Calculator For Six Shapes

Work out the area, perimeter and diagonals of a square, rectangle, parallelogram, rhombus, trapezoid or kite. Each shape asks only for the measurements it genuinely needs, the perpendicular height is distinguished from the slanted side, and the formula is shown with your own numbers substituted into it.

Free Forever Nothing Uploaded Six Shapes Height Not Side
Free Online Quadrilateral Calculator For Six Shapes
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🔷 Quadrilateral Calculator Six shapes · only the measurements each one needs · formula shown

The sum runs in your browser. Nothing you type is sent anywhere.

The shape

🔷 The measurements

Only the boxes this shape needs are shown.

Try one of these
The last one has a perpendicular height greater than the slanted side, which no parallelogram can have.
The area
—
Shape—
Perimeter—
Diagonals—
Extra—

Each formula with your own numbers substituted into it.

What Formula With your numbers
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How to Find the Area of a Quadrilateral

Three steps, and the second is where the mistake usually is.

1
Choose the shape Square, rectangle, parallelogram, rhombus, trapezoid or kite. Each one asks for a different set of measurements, and only the boxes it needs are shown.
2
Mind the difference between height and side For a parallelogram or a trapezoid the height is the perpendicular distance between the parallel sides, not the length of the slanted one. Mixing those two up is the single most common error in this topic, so they have separate boxes here.
3
Read the area, perimeter and diagonals Where a measurement is optional, such as the slanted sides of a trapezoid, the area still comes out without it and only the perimeter waits.

What to Know About Quadrilaterals

Height against side, and which shape is which.

The height is not the slanted side. The area of a parallelogram is the base times the perpendicular height, the straight up distance between the two parallel sides. It is not the base times the slanted side, which would give an answer that is always too large. The two have separate boxes here and the labels say which is which, because putting the slanted length into the height box is the mistake this topic is famous for.
A height taller than the side is impossible. The perpendicular height of a parallelogram can at most equal the slanted side, and it equals it only when the shape is a rectangle. If the height you type is larger, no such shape exists, and it is almost always the two numbers the wrong way round. The page says so rather than quietly producing a bigger area than the shape can hold.
A rhombus needs only its two diagonals. Half the product of the diagonals gives the area of any quadrilateral whose diagonals cross at right angles, which covers both the rhombus and the kite. No angle is needed and no side is needed, which is why those boxes are not asked for. The side length follows from the diagonals rather than the other way round.
A trapezoid gives its area without the slanted sides. The area is the average of the two parallel sides times the height, and nothing else is needed for it. The two slanted sides are only required for the perimeter, so they are optional: leave them blank and you still get the area, with the perimeter waiting.
Every square is a rectangle, and every rhombus a parallelogram. The shapes are nested rather than separate. A square is a rectangle with equal sides and also a rhombus with right angles. The separate options exist because they need different measurements, not because the shapes are unrelated, and the page says which broader families each one belongs to.
It runs in your browser with nothing uploaded. The arithmetic is in the page, so it works offline once loaded and nothing you type is sent anywhere.

Key Features & Capabilities

What it does, and what it deliberately does not.

Six shapes Square, rectangle, parallelogram, rhombus, trapezoid and kite, each with its own measurements.
Height kept apart from side Separate boxes with labels that say which is which, because confusing them is the usual error.
Impossible shapes refused A perpendicular height greater than the slanted side cannot exist, and the page says so.
Diagonals included Given where they are determined, and used as the input where that is the natural measurement.
The formula shown With your own numbers in it, so it can be copied as a method rather than just an answer.
Nothing is uploaded It runs in this tab and keeps working offline.

About Four Sided Shapes

A quadrilateral is any shape with four straight sides, and the familiar ones form a family rather than a list. A square is a rectangle with equal sides. A rectangle is a parallelogram with right angles. A rhombus is a parallelogram with equal sides. A kite and a rhombus both have diagonals that meet at right angles. They are separated here because each needs different measurements, not because they are unrelated shapes.

The formulas are short, and the difficulty is never the arithmetic. It is knowing which length goes where. The area of a parallelogram is its base times its perpendicular height, and the perpendicular height is the straight up distance between the two parallel sides. It is not the length of the slanted side. Those two are different numbers for every parallelogram except a rectangle, and using the slanted side gives an area that is always too big.

That is why this page keeps them in separate boxes with labels that say which is which, and why it refuses a height that is larger than the slanted side. No parallelogram can have one: the perpendicular distance between two lines is the shortest distance between them, so it cannot exceed any other distance across the shape. When those two numbers arrive the wrong way round, saying so is more useful than returning a confident wrong area.

The other decision worth mentioning is which measurements are genuinely required. A rhombus is completely determined by its two diagonals, so asking for an angle as well would be redundant. A trapezoid needs only its two parallel sides and the height for its area; the slanted sides matter only for the perimeter. Making those optional means the area still appears when you do not have them, which is the common case in a homework question.

Frequently Asked Questions

Shapes, heights, diagonals and what is needed.

The height is the perpendicular distance between the two parallel sides, measured straight up. The side is the slanted edge, which is longer. Only the height belongs in the area formula.

Because the perpendicular height you entered is greater than the slanted side. The perpendicular distance between two lines is the shortest distance between them, so no such shape exists. The two numbers are almost always the wrong way round.

No. The two diagonals determine it completely, and half their product is the area. The side length comes out of the diagonals rather than being needed as an input.

Yes. The area is the average of the two parallel sides times the height, and the slanted sides are needed only for the perimeter. Leave them blank and the area still appears.

Yes, and it is also a rhombus. The shapes are nested: a square is a rectangle with equal sides and a rhombus with right angles. The separate options exist because they need different measurements.

Its area comes from the diagonals alone, but a kite has two pairs of equal sides of different lengths, so both are needed for the perimeter.

No. The arithmetic runs in your browser, so nothing you type leaves the page and it works offline.

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