We measured how much JavaScript five analytics tools make your visitors download

June 10, 2026

Every analytics tool works the same way at heart: a script tag on your page sends a request when someone visits. The difference is how much code that script makes every single visitor download first.

We measured it. Here are the compressed transfer sizes — the bytes a visitor's browser actually pulls over the network — measured on June 10, 2026.

How we measured

For our own script and Google's, we downloaded the files and compressed them the way a web server would:

curl -sL https://simplytics.dev/track.js | gzip | wc -c
# 1985 bytes

curl -sL "https://www.googletagmanager.com/gtag/js?id=G-XXXXXXX" | gzip | wc -c
# 139994 bytes

Raw, uncompressed, gtag.js is about 395 KB of JavaScript. And that is before a tag manager container or a cookie-consent banner script, which GA4 setups in the EU usually need — consent platforms commonly add another 35–120 KB.

For Plausible, Fathom, and Matomo we used their own published numbers (Plausible's, Fathom's) and Matomo's forum-documented matomo.js size, since their scripts vary slightly by configuration.

Does ~140 KB actually matter?

For one visit on fast Wi-Fi: not much. Across every visitor, on mobile networks, it adds up to real cost:

• Page weight budgets. 140 KB is more JavaScript than many entire pages ship. If you care about Core Web Vitals, your analytics tool should not be your heaviest script.
• Parse time on cheap phones. Downloading is half the story — a low-end Android phone also has to parse and execute that JavaScript on every page load.
• Data caps. A site with 50,000 monthly pageviews makes its visitors collectively download ~7 GB of analytics JavaScript per month with gtag.js. With a ~1.9 KB script, it is ~100 MB.

The honest caveat

Google Analytics does vastly more than we do — ads attribution, audiences, BigQuery export, predictive metrics. If you use those features, the 140 KB buys you something real. Our argument is narrower: most site owners open analytics to see visitors, pages, referrers, and where traffic comes from. Shipping ~74× the JavaScript for numbers you could get from a 1.9 KB script is a bad trade.

That is the entire idea behind Simplytics: the essential numbers — visitors, views, referrers, countries, devices, traffic channels including AI assistants, sessions, custom events, outbound clicks, funnels — from a ~1.9 KB cookie-less script, for $1/month. You can compare the rest of the trade-offs honestly on our comparison pages, including the full Google Analytics comparison.

Measurements taken June 10, 2026; our own number re-measured June 11, 2026 after custom-event and outbound-click tracking shipped in track.js (1,051 → 1,574 bytes — the new features cost half a kilobyte), and again June 12, 2026 after single-page-app auto-tracking shipped (1,574 → 1,985 bytes). Competitor claims link to their sources; sizes change as vendors update their scripts — if you spot a stale number, email us and we will re-measure.