CSS clamp() Generator

What is CSS clamp() Generator?

The CSS clamp() Generator is a free fluid-typography calculator for front-end developers and designers. You give it a minimum font size, a maximum font size, a minimum viewport width and a maximum viewport width; it returns a clamp(min, preferred, max) declaration where the preferred value mixes a rem offset with a vw slope, so text grows linearly with the screen and never escapes your bounds. This removes the need for stacked font-size media queries and keeps headings and body copy responsive on every device. Pick a preview size to see how the value renders, switch the output unit between rem and px, and copy the line straight into your stylesheet.

How to use CSS clamp() Generator

1. Enter the minimum font size — the size the text should be on the smallest screen.
2. Enter the maximum font size — the size the text should reach on the largest screen.
3. Set the minimum and maximum viewport widths that the size should scale between.
4. Open settings to switch the output unit (rem keeps things accessible; px is also available) if you prefer.
5. Choose a preview size to render sample text at that viewport, then read the live clamp() value.
6. Copy the generated clamp() expression and paste it into your CSS font-size.

Examples

min font 16, max font 20, min vw 320, max vw 1240

font-size: clamp(1rem, 0.913rem + 0.435vw, 1.25rem);

min font 32, max font 64, min vw 320, max vw 1536

font-size: clamp(2rem, 1.474rem + 2.632vw, 4rem);

min font 12, max font 14, min vw 480, max vw 1280

font-size: clamp(0.75rem, 0.675rem + 0.25vw, 0.875rem);

Frequently asked questions

How does the clamp() value scale without media queries?

clamp(min, preferred, max) takes a lower bound, a preferred (fluid) value and an upper bound. The preferred value is a line of the form rem + vw, computed so the font equals your minimum at the minimum viewport and your maximum at the maximum viewport. Between those widths the browser interpolates automatically, and outside them clamp() pins the size to the nearest bound — all in one declaration.

Why is the output in rem instead of px?

Using rem for the fixed parts respects the user's browser font-size setting, which is better for accessibility. The viewport-relative slope is expressed in vw. You can switch the unit to px in settings if your project needs absolute units, but rem is the recommended default.

What viewport range should I use?

A common choice is your smallest supported width (often 320px or 360px) for the minimum and your widest content container (such as 1240px–1536px) for the maximum. The font is fully fluid only inside that range; below it the text stays at the minimum and above it at the maximum.

Does this work for any CSS length, not just font-size?

Yes. The generated clamp() value is just a length, so you can paste it into padding, margin, gap, or any property that accepts a length. The labels mention font-size because fluid typography is the most common use, but the math is identical for spacing.

Is my data sent anywhere?

No. The calculation runs entirely in your browser with JavaScript — your font sizes and viewport widths are never uploaded to any server, so the tool works privately and even offline once the page has loaded.