Golden Ratio Calculator
Enter one measurement and get the matching golden ratio dimensions for layout, type sizing, and design.
Runs entirely in your browser. Nothing you type is uploaded anywhere.
How to use this tool
Type any dimension you already know into the field, then pick what that number represents: the larger segment, the smaller segment, or the whole length. Press Calculate and the tool fills in the other two parts plus the whole length, all based on the golden ratio. Use Copy result to paste the dimensions straight into your design notes or CSS. This is handy for sizing a sidebar against a main column, setting a heading size against body text, or splitting a hero banner into balanced blocks.
How the golden ratio works
The golden ratio, written as the Greek letter phi, is the number 1.618. Two lengths are in golden proportion when the ratio of the larger to the smaller equals the ratio of the whole to the larger. Designers reach for it because layouts and type scales built on 1.618 design dimensions tend to feel balanced. It is closely tied to the Fibonacci sequence: dividing one Fibonacci number by the one before it (such as 89 / 55) gets closer and closer to phi, which is why fibonacci proportion and the golden ratio show up together so often.
A real example
Say your page is 960 pixels wide and you want to split it into a main area and a sidebar using the golden ratio. Treat 960 as the whole length. The larger segment is 960 / 1.618, which is about 593 pixels for the main content, and the smaller segment is about 367 pixels for the sidebar. Together they add back to 960. The same logic works for typography: if your body text is 16px, multiplying by 1.618 gives roughly 26px for a comfortable heading size, and multiplying again gives about 42px for a larger title.
Common questions
What is the golden ratio calculator used for in layout?
It turns one measurement into a balanced pair of dimensions. You give it a column width, font size, image height, or section width, and it returns the matching larger and smaller parts so your layout sizing follows the 1.618 proportion without manual math.
What exact number is the golden ratio?
The golden ratio, phi, is (1 + the square root of 5) divided by 2, which equals about 1.6180339887. Most design work rounds it to 1.618, and this tool uses the full precision number internally for accuracy.
How is the golden ratio related to the Fibonacci sequence?
If you divide any Fibonacci number by the previous one, the result drifts toward phi. For example 13 / 8 is 1.625 and 89 / 55 is about 1.618. That is why a fibonacci proportion is often used as a quick stand-in for the golden ratio in design.
Can I use it for font sizes and type scales?
Yes. Enter your base body size as the smaller segment to get the next size up, or as the larger segment to get a smaller caption size. Repeating the calculation builds a full type scale based on 1.618 design dimensions.
Does the unit matter?
No. The ratio is the same whether you work in pixels, points, ems, centimeters, or inches. Put in whatever unit you design with and the output stays in that same unit.
This tool provides geometric estimates for design and educational use. It is a starting point, not a rule, so trust your eye and adjust dimensions to fit real content.