Common questions

Enter a public URL. Google PageSpeed Insights loads the page once on mobile and once on desktop, as a first visit with nothing cached, and records how much data the initial load transfers; we use the heavier of the two. The test doesn't scroll, so images that only load further down the page aren't counted. We then ask The Green Web Foundation whether the host is listed as green, apply the Sustainable Web Design Model v4, and save a report you can read and share.

No. Email is optional. If you add it, we use it to send you the report. We only send occasional updates if you tick the box to opt in.

If PageSpeed Insights can't load the page, for example because it is private, blocked or timing out, GreenTracer shows an error and saves nothing. We never invent a page weight. Older results saved without a real measurement are shown without a grade.

Each new check creates a fresh result, and the previous result stays in the page's history so you can see how it has changed.

Yes. Every report can be downloaded as a PDF.

It is a modelled estimate, not a meter reading. It is based on the measured size of one first-time, uncached visit and the published averages in the Sustainable Web Design Model v4, including a global average grid intensity of 494 g CO₂e per kWh. It is useful for comparing pages and tracking change. It is not a lifecycle assessment or an audit. The full method is on How it works.

Grades use the digital carbon ratings published with the Sustainable Web Design Model v4, in grams of CO₂e per page view: A+ up to 0.040, A up to 0.079, B up to 0.145, C up to 0.209, D up to 0.278, E up to 0.359, and F above 0.359. See the rating page for more.

We show emissions per page view to three significant figures, for example 0.0151 g or 0.359 g, so the figure lines up with the grade it falls in. That reflects the arithmetic, not the certainty of the estimate, which depends on model averages.

From Lighthouse findings measured on your page during the check, such as unused JavaScript or oversized images. We show up to three, and only when there is a measured finding behind them.

Yes. The Sustainable Web Design Model and The Green Web Foundation's dataset are both public, and we publish the factors we apply and the methodology version on every report, so results can be checked and questioned.

We ask The Green Web Foundation whether your host is listed in its green hosting dataset. If it is, we say "Listed as green" and remove the data-centre operational energy from the estimate, which is about 18% of the total. We don't make our own judgement about a provider.

Your provider may not be listed with The Green Web Foundation, or a CDN, proxy or redirect may hide the underlying host. In that case we say "Not listed as green" or "Not confirmed", rather than guessing. If your provider uses green energy, it can apply to be listed. Check again after any change.

During the beta there are two free public badges. The Carbon grade badge shows your grade and the date of the check, and links to your report. The Hosting badge says “Listed as green” only when The Green Web Foundation lists your host; otherwise it says “Not listed as green” or “Not confirmed”. Get the code on the badge page.

Yes. A Carbon grade badge shows as out of date 180 days after the check, and a Hosting badge after 90 days. Check the page again to refresh it.

Yes. A report shows results for a public web page and has its own link, so you can share it and badges can point to it.

We keep what we need to produce and store reports. If you give your email, we use it to send the report, and for occasional updates only if you opt in. Details are in the Privacy Policy, and you can email support@buzzboost.co.uk with any question.