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Carbon control

A screenshot of the WebPageTest Carbon Control results for It includes information about this site's carbon consumption compared to driving a car and compared to other websites. It also includes a best practices quick check.

The folks at my favorite website performance testing tool, WebPageTest, just introduced Carbon Control, a way to measure your site’s carbon footprint and run no-code experiments to find ways to improve.

One of the big reasons I advocate for simpler, more performant websites is because the web has a huge environmental impact, and improving performance can help reduce it.

Techniques like inlining everything, gzipping and minifying your site, and implementing caching with service workers can all have a big impact.

The WebPageTest Carbon Control feature provides actual numbers around your site.

It estimates the carbon generate per page visit, and shows how that compares to driving a car or visiting the average website. It also provides a list of best practices (and shows you performed against them).

To try it, head over to and paste in the URL for a typical page on your site. Check the Run Carbon Control checkbox, then activate the “Start Test →” button and you’re off to the races!