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Sustainable Web Design scale, from A+ to F
Action plan
Page analysed-
The desktop measurement failed: the mobile result is still valid.
In short
Over a year
What your page emits over a year, depending on your traffic. The rating itself covers a single visit.
How it is calculated
Calculation: Sustainable Web Design v4, as in CO2.js. The network and devices use the electricity of the chosen country (Ember averages, as used by CO2.js). Low end of the range: usage energy only, excluding hardware manufacturing. High end: the former coefficient of 0.81 kWh per GB (model v3), still used by other tools. Median web page: 2.2 MB on mobile, 2.5 MB on desktop (HTTP Archive, July 2025), with the same hosting as your page.
Your action plan
The fixes in the order we would make them: the ones that save the most weight first.
0 fixes suggested
Possible rating after the full action planEstimate based on the files measured by Lighthouse.
Already good
Not checkable from the address
Not checkable: our reading of the page was blocked, or the page has nothing of this kind to check.
Where the weight comes from
What a visitor downloads on arrival, before scrolling.
The heaviest files
Speed in detail
Lab measurements by Google Lighthouse. On mobile: a simulated phone, on a slow mobile connection.
Server response time depends on where Google runs the test from: it is shown, not rated.
Accessibility (quick check)
An automated check only sees part of the issues. The European Accessibility Act has applied to many online shops since June 2025; France uses RGAA 4.1.2 (106 criteria).
No issue detected automatically.
Hosting
Third-party services
Services from other companies that the page loads as soon as a visitor arrives.
Shall we take care of it?
We make your current website lighter without starting over, with measurements before and after. Free quote, no strings attached.
The method
How we calculate
This is a dated estimate, not a certification or a label.
The full methodCalculation: CO2.js (Green Web Foundation, Apache-2.0 licence). Hosting: Green Web Foundation directory (ODbL licence). Comparison: HTTP Archive. Measurement: Google Lighthouse. Third parties: third-party-web (MIT licence).