Grades explained
What your carbon grade means
Every report gives the page a grade from A+ to F. It's based on our estimate of the CO₂e produced by one visit. Lighter pages produce less, so they earn better grades.
The scale, grade by grade
Each grade has an upper limit in grams of CO₂e per page view. The last column shows roughly how much data a page can transfer before it reaches that limit, on a host that isn't listed as green.
| Grade | Upper limit (g CO₂e per page view) | Page size at limit |
|---|---|---|
| A+ | 0.040 | 270 kB |
| A | 0.079 | 533 kB |
| B | 0.145 | 978 kB |
| C | 0.209 | 1.41 MB |
| D | 0.278 | 1.88 MB |
| E | 0.359 | 2.42 MB |
| F | Over 0.359 | Over 2.42 MB |
A grade applies to one initial, uncached load of the page, measured without scrolling. Page sizes use 0.300 kWh per GB and 494 g CO₂e per kWh, with decimal units (1 MB is 1,000,000 bytes). A host listed as green lowers the estimate by about 18%, so its pages can be a little larger for the same grade.
Where the grades come from
We don't set our own thresholds. The grades follow the digital carbon ratings published alongside the Sustainable Web Design Model v4 (SWDM v4), so a grade from GreenTracer means the same as one from any other tool that uses them.
GreenTracer moved to SWDM v4 in October 2026. Grades from before then used an older method, so an earlier result for the same page may differ from a new one even if the page hasn't changed.
A grade is a guide, not a certificate. It rests on an estimate from one measured visit, and the limits of that estimate are explained on how it works.
Find your page's grade
Free to check. Your report shows the grade and what would help most.