What this tool does
The CSS clamp() function sets a value that grows with the viewport but never goes below a minimum or above a maximum. This calculator builds the exact clamp(min, preferred, max) expression so your font sizes and spacing scale smoothly across devices — “fluid typography” — without a jump at each breakpoint.
How it works
Between your minimum and maximum viewport widths, the size interpolates linearly. The preferred value uses vw plus a rem offset so it hits your min size at the small viewport and your max size at the large one.
Example
A heading that is 16px on a 360px phone and 24px on a 1200px desktop produces a single clamp() value you can drop into font-size.