clamp() Calculator – CSS Responsive Font Text Size Calculator

clamp() Calculator for Fonts and Texts

The Result

clamp(1rem, -2.764rem + 16.731vw, 11.875rem)

The clamp() function in CSS is a way of setting responsive styles based on a range. Fluid like text scaling. Its syntax is:

clamp(minimum value, preferred value, maximum value)

The browser will choose the preferred value unless it's smaller than the minimum value or larger than the maximum value, in which cases it will use those boundary values.

Calculations for Responsive Font Size

  1. Values you input:

    • minSize: Minimum font size (px)
    • maxSize: Maximum font size (px)
    • minViewport: Minimum viewport size (px) where minSize applies
    • maxViewport: Maximum viewport size (px) where maxSize applies
    • rootFontSize: Usually 16px for most browsers, but can be customized. This is the base size for computing relative units like rem.
  2. Goal:

    To find an equation in the format of y = ax + b that defines a linear relationship between the viewport size (x) and the font size (y).

  3. Calculations:

    a: The slope of the line, which represents how much the font size should change for every pixel change in viewport size. It's calculated using:

    a = (maxSize - minSize) / (maxViewport - minViewport);

    b: This is the y-intercept and it's found by rearranging the equation y = ax + b to solve for b. Using the point (minViewport, minSize), it's calculated as:

    b = minSize - a * minViewport / rootFontSize;

  4. The Result:

    The resulting equation y = ax + b can be translated into clamp() syntax:

    clamp(minSize / rootFontSize rem, b rem + a viewportUnits, maxSize / rootFontSize rem)

The reason for using a linear relationship between viewport and font size is to ensure a smooth and consistent scaling of the font size as the viewport changes size.

Browser Compatibility: