How this calculator works
The golden ratio splits a positive length so that the ratio of the whole to the longer section equals the ratio of the longer section to the shorter section. Choose which of the three lengths you know; the other two follow from the constant phi. Unit conversions happen before calculation, so all returned lengths describe the same physical split.
Formula
phi = (1 + sqrt(5))/2; a/b = (a+b)/a = phi; a = phi b; whole = a+b.
Worked example
If the shorter section is 1 m, the longer section is about 1.618033989 m and the whole is 2.618033989 m. A whole length of 1 m splits into about 0.618033989 m and 0.381966011 m.
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Frequently asked questions
Is the ratio exactly 1.618?
No. Phi is irrational, so 1.618 is only a rounded approximation.
Can I use inches or feet?
Yes. Select the input unit and a suitable unit for each length output. The constant ratio itself has no unit.
Does the calculator judge a design?
It only calculates a geometric proportion. Whether that proportion suits a design is a separate decision.