Enter any length and get its golden-ratio partner — whether you know the longer part, the shorter part, or the whole. φ ≈ 1.618.
What the golden ratio is
Two lengths are in the golden ratio when the whole relates to the longer part exactly as the longer relates to the shorter — a proportion that works out to φ = (1+√5)/2 ≈ 1.6180. Designers and photographers reach for it as a pleasing division; mathematicians love it because it is the most irrational of numbers. Give this calculator any one length and say which role it plays, and it returns the full golden pair.
How to use it
- Enter the length you know.
- Say whether it’s the longer part, the shorter part, or the whole.
- Read the complete a : b pair and the whole.
The formula
A worked example
A 100-unit longer part pairs with 100 ÷ φ = 61.8 — the golden pair 100 : 61.8, whole 161.8. Working from a whole instead: a 1000-pixel banner divides at 618 and 382, the split behind countless layout grids. And the Fibonacci connection is real: 5, 8, 13, 21… — each neighbour pair’s ratio marches closer to φ.