Question 1

What is PageLens?

Accepted Answer

PageLens is a free Chrome extension that estimates the carbon footprint of any web page and turns it into an actionable A–F Eco Score, with concrete recommendations to make the page lighter.

Question 2

How does PageLens estimate CO2 emissions?

Accepted Answer

It measures the bytes transferred when a page loads and applies CO2.js (the Sustainable Web Design model) from The Green Web Foundation, adjusting the estimate for whether the site is hosted on green energy.

Question 3

How is the Eco Score calculated?

Accepted Answer

The Eco Score is a 0–100 rating, graded A–F, that blends four factors: carbon per view (40%), page weight (30%), green hosting (15%) and best practices (15%).

Question 4

Is PageLens free?

Accepted Answer

Yes. PageLens is completely free to use and open about how its score is calculated.

Question 5

Does PageLens collect my data?

Accepted Answer

No. PageLens analyzes the current page locally in your browser. Only the site's hostname is sent to The Green Web Foundation to check for green hosting. There is no tracking, no analytics, and no account required.

Question 6

Is the carbon estimate exact?

Accepted Answer

No — it is an actionable estimate, not a precise measurement. PageLens is transparent about its methodology and clearly flags any figure it has to approximate.

See the carbon footprint of any web page.