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Prelumen Analytics

Your page weight has a footprint. Weigh it.

A fast estimate of CO₂ per page view based on transfer size — the starting point for a lighter, faster website.

Is this your website?
  • See grams of CO₂ per page view, not a vague rating
  • Find out which asset type carries the weight
  • Get a baseline you can measure the next version against

Weigh a page

Enter a URL and get grams of CO₂ per page view, with the asset breakdown behind the number.

Transfer size, measured

Fetches the page and its assets and adds up what a visitor actually downloads — HTML, CSS, JavaScript, images, video and fonts.

Asset breakdown

Bytes and counts per asset type, so the heaviest category is obvious before you start optimising.

Published model

Energy and emission factors come from the Sustainable Web Design Model v4 and IEA 2024 grid data, not from a black box.

Repeatable baseline

Every check is stored against the page, so a later run shows whether a change moved the number.

How is the estimate calculated?
Transfer size is multiplied by energy-intensity factors from the Sustainable Web Design Model v4, combined with IEA 2024 grid data. The constants are fixed and documented, so two runs of the same page are comparable.
Does this check green hosting?
No. Hosting is not looked up here. The Advanced Carbon Check queries the Green Web Foundation for that.
How many assets are measured?
Up to 50 assets per page. Pages beyond that are measured on the first 50, which covers the weight of almost every real page.
Which carbon checker should I use?
This one for a quick page-weight number. The Advanced Carbon Check adds Google PageSpeed Insights data and green-hosting verification, and costs more.

Every check runs on our servers: you provide a public URL, there is nothing to install, and pages are rendered with JavaScript first so single-page apps are read the same way a browser reads them. Each result gets a permanent link you can share. On a website you have claimed, findings become tracked issues, and result pages offer AI summaries and developer guidance on plans that include them.