The Average Website Loads 375KB of Third-Party JavaScript

    Third-party JavaScript on the median mobile page grew from 255 KB in 2020 to 375 KB in 2024, roughly two-thirds of all JS on a typical page.

    Median third-party JavaScript on the mobile page (KB)
    2020
    255 KB
    2022
    292 KB
    2024
    375 KB

    Source: HTTP Archive Web Almanac JavaScript chapters, 2020, 2022, and 2024 editions.

    50th-percentile values across the HTTP Archive mobile crawl. CNAME-cloaked third parties are not included, so figures are a lower bound.

    First-party vs third-party JavaScript on the median mobile page (KB)
    First-party JS
    168 KB
    Third-party JS
    375 KB

    Source: HTTP Archive Web Almanac, 2024 JavaScript chapter.

    External scripts outweigh first-party code by more than 2× on the typical page.

    Source: The Average Website Loads 375KB of Third-Party JavaScript - PageSpeed Matters