About the Kite Calculator
A kite is a four-sided shape with two pairs of equal sides next to each other, and diagonals that cross at right angles. This calculator uses the lengths of the two diagonals and the point where the cross diagonal meets the long one, and from them it works out the area, the two different side lengths and the perimeter. Type the long diagonal, the cross diagonal and where they meet and the kite area appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Kite Calculator
- 1Enter the long diagonal, the cross diagonal and where they meet.
- 2Pick the units or options from the menus if the kite area tool offers them.
- 3Read the kite area in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the kite area
Designers use it for flying kites, signs, tiles and jewellery. Students use the area formula as an exercise in geometry, and carpenters use it to cut kite-shaped panels from their diagonals.
If the crossing point is exactly in the middle of the long diagonal, the kite is a rhombus and all four sides are equal, which you can check with the results.
How the kite area is worked out
Area = ½ × diagonal 1 × diagonal 2. Each short side is √(x² + (d2 ÷ 2)²) and each long side is √((d1 − x)² + (d2 ÷ 2)²), where x is the distance along d1 to the crossing point. A kite with a long diagonal of 10, a cross diagonal of 6, crossing 3 from the top, has an area of 30, short sides of 4.243, long sides of 7.616 and a perimeter of 23.72.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Area from diagonals
- Both pairs of sides
- Perimeter shown
Mistakes to avoid with kite area
The cross diagonal must be perpendicular to the long one, which is what makes the formulas work. The crossing distance must be greater than zero and less than the long diagonal. A value outside that range cannot form a kite.
On phone and computer
On a phone, type into the boxes one after another and read the kite area underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the kite area move. The kite calculator works the same on both. Shapes with equal sides are close relatives. Check a diamond with Rhombus Calculator and a slanted rectangle with Parallelogram Calculator, break a kite into two pieces with Triangle Calculator, and use Area Calculator for others.
Features
- Diagonals meet at 90°
- Mid-point crossing gives a rhombus
- Same units throughout
- Clear messages when the kite area inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate kite area?
Area = ½ × diagonal 1 × diagonal 2. Each short side is √(x² + (d2 ÷ 2)²) and each long side is √((d1 − x)² + (d2 ÷ 2)²), where x is the distance along d1 to the crossing point. A kite with a long diagonal of 10, a cross diagonal of 6, crossing 3 from the top, has an area of 30, short sides of 4.243, long sides of 7.616 and a perimeter of 23.72.
What is the formula for kite area?
Area = ½ × diagonal 1 × diagonal 2. Each short side is √(x² + (d2 ÷ 2)²) and each long side is √((d1 − x)² + (d2 ÷ 2)²), where x is the distance along d1 to the crossing point. The kite calculator applies it exactly and rounds only the displayed answer to six significant figures.
How do I find the area of a kite?
Multiply the two diagonals and divide by two. This works for any shape whose diagonals are perpendicular.
What if I know the sides but not the diagonals?
You also need an angle or a diagonal. With the two side lengths and the long diagonal you can find the rest by the cosine rule.
Is a rhombus a kite?
Yes, a special one with four equal sides.
Is this kite calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.