Divide a line so that the longer part divided by the shorter equals the whole divided by the longer. That ratio, roughly 1.618, is the golden ratio. It has fascinated mathematicians, artists, and architects for over two thousand years. The ancient Greeks used it in the Parthenon, or so the story goes. Renaissance painters and architects wrote about it. Le Corbusier built a whole proportion system, the Modulor, around it.

Designers use the golden ratio to set proportions for layouts, type scales, and image crops. A common approach is the golden rectangle, where the ratio of width to height is 1.618. Another is the rule of thirds, a simplification that divides a frame into a 3 by 3 grid and places key elements along the lines or at intersections. Photographers use it constantly. So do web designers laying out columns and sidebars.

Practical uses

• Page layouts with a main column and a narrower sidebar.
• Type scales that step by roughly 1.618.
• Image crops that follow the golden rectangle.
• Logo construction grids based on the ratio.

The golden ratio is not magic. Designs that ignore it can look fine. But it offers a reliable starting point when proportions feel off.