RunLocalTools

Fluid Typography Clamp() Calculator

Enter a minimum font size, a maximum font size, and the viewport range you want them to apply across, and get back a ready-to-use CSS clamp() expression for fluid typography — text that scales smoothly between screen sizes instead of jumping abruptly at each breakpoint.

Why clamp() beats breakpoint-based font sizing

The traditional way to handle responsive typography is a handful of media query breakpoints, each setting a fixed font size for a range of screen widths — which works, but produces visible jumps in text size right at each breakpoint, and needs a media query written and maintained for every size you want to support. clamp() does something more elegant: it defines a minimum size, a maximum size, and a fluid value in between (usually based on viewport width) that scales continuously, so text grows and shrinks smoothly across every screen size in between, with no breakpoints and no jumps. The catch is that the math behind a good clamp() expression — getting the fluid middle value right — isn’t obvious to write by hand, which is exactly the gap this tool fills.

How to use it

  1. Enter your minimum font size (the smallest it should ever render, typically at your smallest supported viewport) and maximum font size (the largest, typically at your largest supported viewport).
  2. Enter the viewport width range you want the scaling to happen across.
  3. The tool calculates the correct clamp() expression, including the fluid middle value, and shows a live preview of how the text scales.
  4. Copy the generated CSS directly into your stylesheet.

Common situations this solves

  • Building fluid, responsive typography without writing and maintaining multiple font-size media queries
  • Getting the clamp() math right without working out the slope-intercept calculation by hand
  • Previewing how a heading or body text size will actually scale across screen widths before committing the CSS
  • Replacing a stack of breakpoint-based font-size rules with a single fluid declaration

FAQ

Does clamp() work in all modern browsers?

Yes — clamp() has strong support across all modern browsers at this point, making it a safe choice for production use rather than an experimental CSS feature you need to guard with fallbacks.

Should I use this for every text element, or just headings?

Fluid typography is most commonly applied to headings and large display text, where size jumps are most visually noticeable — body text is often left at a fixed, readable size or given a much narrower fluid range, since large swings in body text size can affect line length and readability.

Can this generate clamp() expressions for things other than font size, like spacing or padding?

The same clamp() math applies to any CSS length value, though this tool is specifically framed around font sizing — the same min/preferred/max logic works for spacing and padding values if you adapt the numbers accordingly.

What units does the generated clamp() use?

Check the output — fluid typography clamp() expressions are typically built using rem for the min/max bounds and viewport-relative units (like vw) for the fluid middle term, which is standard practice for this kind of responsive sizing.