Golden ratio calculator

A line is split in the golden ratio when the longer part A and shorter part B satisfy (A + B) / A = A / B. The common ratio is φ = (1 + √5) / 2 ≈ 1.6180339887.

Golden ratio input

Golden segments
A = 100
B = 61.8034
A + B = 161.8034
A / B
1.6180339887
(A + B) / A
1.6180339887
B / A (1/φ)
0.6180339887
A (longer) B (shorter)

What is φ?

The golden ratio is the unique positive solution of x² = x + 1:

φ = (1 + √5) / 2 ≈ 1.6180339887498948…

The reciprocal 1/φ equals φ − 1 ≈ 0.618, and its square φ² equals φ + 1 ≈ 2.618. These self-similar relationships are why φ shows up in nature, architecture, and design.

How to compute the segments

  • From A: B = A / φ, total = A + B = A · φ.
  • From B: A = B · φ, total = A + B.
  • From total (A + B): A = total / φ, B = total − A.

FAQ

Where does φ appear in nature?

Approximate appearances include sunflower seed spirals, pinecone scales, and the arrangement of leaves on stems (phyllotaxis) — all because φ is the "most irrational" number, which spreads things apart most evenly.

Is φ related to the Fibonacci sequence?

Yes — the ratio of consecutive Fibonacci numbers (1, 1, 2, 3, 5, 8, 13, 21, …) approaches φ. So 21/13 ≈ 1.615, 34/21 ≈ 1.619, and so on.

How accurate is φ here?

The calculator uses double-precision floating point, so values are accurate to about 15 significant digits.

Related calculators