https://vercel.com
Sustainability
· 8 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
79
GRADE
C
FIX
0
REVIEW
5
PASS
2
INFO
1
Checks
82 PASS 5 REVIEW
BCO2 Per Page Load0.50g CO2 per viewREVIEW
CO2 Per Page Load
0.50g CO2 per view
0.50g CO2 per view
Info::
0.50g CO2 per page view
This page transfers 2.1 MB, producing an estimated 0.50g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.10g, end-user device 0.39g.
Got: 0.50g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 60.2 kg CO2/year
With 10,000 page views per month, this page would generate approximately 60.2 kg of CO2 annually — equivalent to charging 7520 smartphones.
Info::
Green hosting reduces data center emissions
0.50g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 60% of websites
Sustainable Web Design model v4 · Page size: 2.1 MB
Your site
0.50g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.01g
Network
0.10g
End-user device
0.39g
At 10,000 monthly views: Monthly: 5.0 kg · Annual: 60.2 kg · ≈ 7520 smartphone charges
BCarbon Budget40th percentileREVIEW
Carbon Budget
40th percentile
40th percentile
Info::
0.50g CO2 — below the median website (0.60g)
Better than an estimated 60% of websites, but above the sustainability target of 0.50g. Reducing page weight would help reach the target.
Info::
Estimated 40th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.50g
40th percentile
Cleaner than 60% of websites
✗ Above the median website
vs Median 16% cleaner ✓
vs Target 0% more
CTransfer EfficiencyAction74% efficientREVIEW
Transfer Efficiency
Action74% efficient
74% efficient
Warning::
Transfer efficiency: 74%
An estimated 556 KB (26%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 556 KB of unused JavaScript. This wasted data produces 0.13g of unnecessary CO2 per page view.
Total waste: 556 KB (26% of page weight)
Unused JS 556 KB
0.13g unnecessary CO2 per visit
Actual transfer 2169 KB
Theoretical minimum 1612 KB
Potential savings 556 KB (0.13g CO2)
See Deep Analysis sections above for specific optimizations.
BWeb Font Weight VariantsNo detectable Google Fonts weightsREVIEW
Web Font Weight Variants
No detectable Google Fonts weights
No detectable Google Fonts weights
Info::
No detectable Google Fonts weights
The analyzer detects font weights via Google Fonts URL parameters (~70% of font-using sites). Self-hosted fonts and non-Google CDN fonts aren't visible to URL-based detection. If you self-host fonts, manually audit how many @font-face weights you ship -- 2-3 weights per family is typically enough; 5+ is usually unused payload.
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::
Vercel CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Vercel: Hosted on AWS/Google Cloud with renewable energy commitments
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 Amazon Web Services✗CDN Vercel✓
Vercel: Hosted on AWS/Google Cloud with renewable energy commitments
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight97% cachedPASS
Repeat Visit Weight
97% cached
97% cached
Info::
97% reduction on repeat visits
Returning visitors download only 55 KB (vs 2169 KB first visit). 123 of 124 resources are served from browser cache, saving 0.49g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.50g)
First visit
2169 KB
Repeat visit
55 KB
97% reduction on repeat visits
Saving 0.49g CO2 per returning visitor
123 resources served from cache · 1 resources re-downloaded
Image Optimization17 images, 1 KB total, 0 KB wastedINFO
Image Optimization
17 images, 1 KB total, 0 KB wasted
Image Optimization Audit
Total Images
17
Total Size
1 KB
5 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.