CO2Stats

The Kettle Question

A website visit

Emissions for one page view, or one second of browsing. Each entry records the claim as published: what it counts, who made it and who paid, and any dispute. Figures with different boundaries are not comparable without reading what each counts.

One second of visiting a typical website, Alex Wissner-Gross's figure

  • a mean of 0.02 g CO2 per second of browsing a typical website (published as: about 20 milligrams of CO2 per second (converted from mg to g))

"Our work has nothing to do with Google. Our focus was exclusively on the Web overall, and we found that it takes on average about 20 milligrams of CO2 per second to visit a Web site."

Harvard Physicist Sets Record Straight on Internet Carbon StudyTechNewsWorld (Renay San Miguel; archived copy on the Wayback Machine), press article, 2009-01-12

What one action is
Visiting a website, averaged over the web as a whole
Scope
not stated
Counts
not stated
Leaves out
not stated
Model or version
not stated
Place
not stated
Period measured
not stated
Method
not stated
Claimed by
Company: Alex Wissner-Gross (Harvard University), who ran CO2Stats.com at the time (this site's 2009 predecessor), quoted by TechNewsWorld
Paid for by
not stated
Dispute
none

History

  • Added.

Median web page view as of July 2023, Website Carbon Calculator

  • a median of 0.8 g CO2e per page view

Status: superseded. See the newer claim.

We used data from HTTP Archive. This is the median average and not the mean average. ... For reference, the median is approximately 0.8 grams per page view as of July 2023.

FAQ - Website Carbon CalculatorWholegrain Digital (Website Carbon Calculator), company statement, 2023-07

What one action is
One view of a typical web page (median of pages in HTTP Archive data)
Scope
not stated
Counts
not stated
Leaves out
not stated
Model or version
not stated
Place
global
Period measured
July 2023
Method
Median of HTTP Archive page data; the FAQ says CO2 on the site always means CO2e.
Claimed by
Company: Wholegrain Digital
Paid for by
none
Dispute
none

History

  • Added.

Average web page view, Website Carbon Calculator (Sustainable Web Design Model v4)

  • 0.36 g CO2e per page view

Globally, the average web page produces approximately 0.36 grams CO2 equivalent per pageview.

Website Carbon Calculator v4Wholegrain Digital (Website Carbon Calculator), company statement, 2025-09-17

What one action is
One view of a typical web page, averaged globally
Scope
end to end
Counts
data centres (hosting); transmission networks; user devices; operational and embodied emissions
Leaves out
the type of user device (not taken into account)
Model or version
Sustainable Web Design Model v4
Place
global (global average grid intensity)
Period measured
not stated
Method
Page data transfer converted to emissions with the Sustainable Web Design Model v4 (adopted by the calculator on 14 July 2025); the page says "average" and does not say which average.
Claimed by
Company: Wholegrain Digital
Paid for by
none
Dispute
none

The calculator uses this figure: Website visit (Website Carbon's global average page).

History

  • Added.
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