What is the golden ratio?
The golden ratio is a special number, about 1.618, often written with the Greek letter phi. Two quantities are in the golden ratio when their ratio equals the ratio of their sum to the larger one.
If a line is divided so that the whole length divided by the longer part equals the longer part divided by the shorter part, the ratio is the golden ratio. Its exact value is one plus the square root of five, divided by two. Like pi, it is an irrational number, with decimals that go on forever without repeating.
The golden ratio is closely linked to the Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13 and so on. Dividing each number by the one before it gets closer and closer to 1.618. It also appears in geometry, such as in regular pentagons and five-pointed stars.
Fact and myth
Some plants, such as sunflowers and pinecones, arrange seeds in spirals linked to Fibonacci numbers. Many claims about the golden ratio in the Parthenon, the Mona Lisa or the human body are exaggerated or unproven. Still, designers sometimes use it to create pleasing proportions.
Did You Know?
A rectangle whose sides are in the golden ratio is called a golden rectangle. Cutting a square off one end leaves another, smaller golden rectangle.