CSS Clamp() Generator (Create Fluid Typography Online)
Fluid typography makes websites perfectly responsive across all devices without needing dozens of media queries. Just input your minimum and maximum screen sizes and your desired font sizes, and this tool will calculate the exact CSS clamp() mathematical formula for you.
100% Private & Secure
This tool runs completely inside your browser using client-side WebAssembly and JS. Zero data is ever sent to our servers.
Viewport Width (px)
Font Size (px)
How to use this tool
- Set your Minimum Viewport width (usually mobile, e.g., 320px).
- Set your Maximum Viewport width (usually desktop, e.g., 1280px).
- Set the Minimum Font Size you want on mobile screens.
- Set the Maximum Font Size you want on large screens.
- The tool instantly calculates the REM-based clamp() function. Click 'Copy CSS' and paste it into your stylesheet.
Example Usage
Min Viewport: 320px, Max Viewport: 1280px Min Font: 16px, Max Font: 24px
font-size: clamp(1rem, 0.8333rem + 0.8333vw, 1.5rem);
When to use this tool
- Creating fluid, responsive typography that smoothly scales between mobile and desktop.
- Sizing responsive paddings and margins using a single line of CSS instead of media queries.
- Building modern, robust design systems that adapt perfectly to ultra-wide and ultra-narrow displays.
Frequently Asked Questions
What is the exact mathematical formula behind fluid typography clamp()?
The formula calculates a linear equation defined by two points on a graph: (min-viewport, min-font) and (max-viewport, max-font). The 'Slope' determines how fast the font grows between these breakpoints. The 'y-axis intersection' sets the base size relative to the viewport. The generator combines these into a single clamp(min, intersection + slope * 100vw, max) function.
Why should I use REMs instead of Pixels for the bounds?
Accessibility (a11y) is the primary reason. If a user changes their browser's default font size from 16px to 24px because of visual impairment, REMs scale dynamically to respect their choice, ensuring your UI remains readable. Hardcoded pixels explicitly override their browser settings.
Are there performance benefits to using clamp() over media queries?
Yes. Every CSS media query breakpoint adds bytes to your CSS file and requires the browser's CSSOM to recalculate layout properties when the viewport hits that specific width. A single clamp() declaration allows the browser to compute the size natively during the paint operation, vastly reducing CSS file size and complexity.
What happens on zoom or ultra-wide displays?
This is exactly why the third parameter (maximum bound) exists in the clamp() function. Once the viewport width exceeds your defined maximum viewport boundary, the font size instantly stops scaling and locks at the maximum REM size. This prevents headlines from becoming absurdly large on 4K monitors.
Does clamp() work on older browsers like Internet Explorer 11?
No, CSS clamp() is not supported in IE11 or older versions of Safari. However, all modern browsers natively support it. If you have strict legacy support requirements, you should provide a fallback font-size declaration immediately preceding your clamp() declaration.