What is a rhombus?
A rhombus is a four-sided shape with all four sides the same length.
The answer
A rhombus has 4 sides, 4 vertices and 2 pairs of parallel sides. The one drawn here has 2 lines of symmetry. A square has 4. The angles inside a rhombus add up to 360°.
Rhombus diagram and properties
| Property | Count |
|---|---|
| Sides | 4 |
| Vertices (corners) | 4 |
| Angles add up to | 360° |
| Right anglesA square is a rhombus with 4. | 0 |
| Pairs of parallel sides | 2 |
| Lines of symmetryA square has 4. | 2 |
Key facts about the rhombus
- Its opposite sides are parallel, so a rhombus is a special parallelogram.
- Opposite angles are equal. The two diagonals are its lines of symmetry, and they cross at a right angle.
- A square is a rhombus whose angles are all right angles.
- People often call it a diamond, but rhombus is the word 11+ papers use.
Where you see it
The diamond on a playing card, the pattern on an argyle jumper and some road signs turned on their corner.
The common mistake
Thinking a square turned on its corner becomes a rhombus that is not a square. Turning a shape never changes its name: a square turned round is still a square, with four right angles.
An 11+ style question
A rhombus has a perimeter of 36 cm. How long is each side?
Answer: 9 cm
- All four sides of a rhombus are the same length.
- 36 ÷ 4 = 9, so each side is 9 cm.
Related shapes and skills
More shapes
Questions parents ask
How many sides and vertices does a rhombus have?
A rhombus has 4 straight sides and 4 vertices (corners). Its angles add up to 360°.
How many lines of symmetry does a rhombus have?
A rhombus like the one drawn here has 2 lines of symmetry. A square has 4.
Is a square a rhombus?
Yes. A square has four equal sides, which is all a rhombus needs. A square is a rhombus with four right angles, just as it is a rectangle with four equal sides.
What is the difference between a rhombus and a kite?
A rhombus has all four sides equal and two pairs of parallel sides. A kite has two pairs of equal sides that sit next to each other, and no parallel sides.
Shape questions are quick marks in the 11+
Angles, symmetry, nets and 3D shapes come up in 11+ maths and non-verbal reasoning. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.