Zach’s ugly mug (his face) Zach Leatherman

Get all Font Sizes in use on a Web Page

January 10, 2019 On Twitter (archived)

While doing some testing on font hinting, I wanted an easy way to make a test page that had examples of every single font-size in use on a page. Pasting the following snippet into your DevTools console retrieves an Array of sorted font-size values in use on a page.

(function() {
  let fontSizes = new Set();

  document.querySelectorAll("*").forEach(function( node ) {
    fontSizes.add( window.getComputedStyle( node ).getPropertyValue("font-size") );

  return Array.from( fontSizes ).sort(function(a, b) {
    return parseFloat(a) - parseFloat(b);

For example, this page returned:

["10.5px", "11px", "12px", "13px", "15px", "15.7368px", "16px", "16.9474px", "18.6875px", "19.2px", "21.7895px", "22.4px", "23px", "100.35px"]

⚠️ Careful if you use vw units, these are computed values only.

I’ve also filed this as a possible enhancement for GlyphHanger.

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Zach Leatherman IndieWeb Avatar for a builder for the web at IndieWeb Avatar for He is the creator and maintainer of IndieWeb Avatar for https://www.11ty.devEleventy (11ty), an award-winning open source site generator. At one point he became entirely too fixated on web fonts. He has given 79 talks in nine different countries at events like Beyond Tellerrand, Smashing Conference, Jamstack Conf, CSSConf, and The White House. Formerly part of Netlify, Filament Group, NEJS CONF, and NebraskaJS. Learn more about Zach »

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How did you do this? I automated my Open Graph images. (Peer behind the curtain at the test page)