https://synthesia.io
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
84
GRADE
B
FIX
0
REVIEW
4
PASS
2
INFO
0
Checks
62 PASS 4 REVIEW
BCO2 Per Page Load0.61g CO2 per viewREVIEW
CO2 Per Page Load
0.61g CO2 per view
0.61g CO2 per view
Info::
0.61g CO2 per page view
This page transfers 2.6 MB, producing an estimated 0.61g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.13g, end-user device 0.47g.
Got: 0.61g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 73.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 73.7 kg of CO2 annually — equivalent to charging 9213 smartphones.
Info::
Green hosting reduces data center emissions
0.61g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 50% of websites
Sustainable Web Design model v4 · Page size: 2.6 MB
Your site
0.61g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.02g
Network
0.13g
End-user device
0.47g
At 10,000 monthly views: Monthly: 6.1 kg · Annual: 73.7 kg · ≈ 9213 smartphone charges
BCarbon Budget50th percentileREVIEW
Carbon Budget
50th percentile
50th percentile
Warning::
0.61g CO2 — above the median website (0.60g)
Heavier than an estimated 50% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 50th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.61g
50th percentile
Cleaner than 50% of websites
✗ Above the median website
vs Median 2% more
vs Target 23% more
BTransfer Efficiency84% efficientREVIEW
Transfer Efficiency
84% efficient
84% efficient
Info::
Transfer efficiency: 84%
An estimated 431 KB (16%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 431 KB of unused JavaScript. This wasted data produces 0.10g of unnecessary CO2 per page view.
Total waste: 431 KB (16% of page weight)
Unused JS 431 KB
0.10g unnecessary CO2 per visit
Actual transfer 2657 KB
Theoretical minimum 2225 KB
Potential savings 431 KB (0.10g CO2)
See Deep Analysis sections above for specific optimizations.
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
ActionWhether the site is served from green-energy infrastructure
Green Hosting
No green hosting detected
AGreen HostingGreen (cdn)PASS
Green Hosting
Green (cdn)
Green (cdn)
Info::
Cloudflare CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Cloudflare: 100% renewable energy for global network since 2019
Info::
Green hosting status based on known provider commitments
Green hosting detection uses a curated database of provider renewable energy commitments. This is not a real-time verification. For authoritative checks, visit thegreenwebfoundation.org.
Green Hosting✓ Green Hosted
Hosting Not identified✗CDN Cloudflare✓
Cloudflare: 100% renewable energy for global network since 2019
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight95% cachedPASS
Repeat Visit Weight
95% cached
95% cached
Info::
95% reduction on repeat visits
Returning visitors download only 137 KB (vs 2657 KB first visit). 136 of 139 resources are served from browser cache, saving 0.58g CO2 per repeat visit.
Info::
Repeat visit: 0.03g CO2 (first visit: 0.61g)
First visit
2657 KB
Repeat visit
137 KB
95% reduction on repeat visits
Saving 0.58g CO2 per returning visitor
136 resources served from cache · 3 resources re-downloaded
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.