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Fluid Type Scale Calculator

Generate font size variables for a fluid type scale with CSS clamp.


Customize everything, grab the output CSS, and drop it into any design system. Share the URL with your team members or use it to document your CSS.


  • Fully customizable parameters for everything:
    • Baseline min/max font size, screen width, type scale.
    • The names of the steps in your type scale.
    • The prefix to use for the variable names.
    • The max number of decimal places in the output.
    • Whether to show output in rems or pixels.
    • The resolved pixel value of 1rem.
  • Output CSS variables for fluid font sizing.
  • Live preview table. Pick a font and enter some sample text to fine-tune the results.
  • Link sharing.

Link Sharing

The /calculate route accepts the following query parameters and types. All parameters except boolean flags are required. Booleans that are not specified in the URL are treated as unchecked (false).

Param Description Type Constraints
minFontSize The minimum font size for the base step number > 0 && < maxFontSize
minWidth The viewport or container width corresponding to the minimum font size number > 0 && < maxWidth
minRatio The type scale ratio for the minimum font size of each step number > 0 && < maxRatio
maxFontSize The maximum font size for the base step number > 0 && > minFontSize
maxWidth The viewport or container width corresponding to the maximum font size number > 0 && > minWidth
maxRatio The type scale ratio for the maximum font size of each step number > 0 && > minRatio
steps A comma-separated list of names for your type scale steps, in ascending order of font size string Comma-separated list. Step names must be alphanumeric, with no spaces. No duplicates are allowed.
baseStep The name of the base step string Non-empty string. Must appear in steps.
prefix The naming convention to use for the output CSS variables string Non-empty alphanumeric string.
includeFallbacks Whether to include fallback variables in the CSS output for browsers that don't support clamp. on, true, or false
useRems Whether to use rems for font sizing. on, true, or false
useContainerWidth Whether to use container width (cqi) instead of viewport width. on, true, or false
remValue The computed pixel value of 1rem. Useful if your app changes the root font size (e.g., with the popular 62.5% font size trick). Note: This parameter has no effect if useRems is omitted. number > 0
decimals The number of decimal places to round the output to. int >= 0 && <= 10
previewFont The font family to render in the preview. string Non-empty string. Spaces must be escaped (e.g., Libre+Baskerville). The font must be a valid Google Font. Custom fonts are not supported.
previewText The text to render in the preview table. string Non-empty string. Spaces must be escaped (e.g., This+is+a+sentence).
previewWidth The width to simulate in the preview table. number > 0

Example URL:

Tech Stack

  • SvelteKit
  • Sass
  • TypeScript

Running Locally

  1. Clone the repo.
  2. Run pnpm install to install dependencies.
  3. Run pnpm run dev and visit localhost:5173 to view the app.

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