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https://Pennycalc.com

Sustainability

· 7 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
85
GRADE
B
FIX
1
REVIEW
2
PASS
4
INFO
0
Device:
Mobile Desktop
Checks
7
4 PASS 2 REVIEW 1 FIX
D
Transfer Efficiency
Action
47% efficient
FIX
47% efficient
Critical::
Transfer efficiency: 47%
An estimated 278 KB (53%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 278 KB of unused JavaScript. This wasted data produces 0.06g of unnecessary CO2 per page view.
47% efficient

Total waste: 278 KB (53% of page weight)

Unused JS 278 KB

0.06g unnecessary CO2 per visit

Actual transfer 529 KB
Theoretical minimum 251 KB
Potential savings 278 KB (0.06g CO2)

See Deep Analysis sections above for specific optimizations.

B
Web Font Weight Variants
No detectable Google Fonts weights
REVIEW
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.
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
CO2 Per Page Load
0.12g CO2 per view
PASS
0.12g CO2 per view
Info::
0.12g CO2 per page view
This page transfers 0.5 MB, producing an estimated 0.12g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.00g, network 0.03g, end-user device 0.09g.
Got: 0.12g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 14.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 14.7 kg of CO2 annually — equivalent to charging 1836 smartphones.
Info::
Green hosting reduces data center emissions

0.12g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 90% of websites

Sustainable Web Design model v4 · Page size: 0.5 MB

Your site
0.12g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.00g
Network
0.03g
End-user device
0.09g
At 10,000 monthly views: Monthly: 1.2 kg · Annual: 14.7 kg · ≈ 1836 smartphone charges
A
Green Hosting
Green (cdn)
PASS
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 Weight
98% cached
PASS
98% cached
Info::
98% reduction on repeat visits
Returning visitors download only 11 KB (vs 529 KB first visit). 19 of 20 resources are served from browser cache, saving 0.12g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.12g)
First visit
529 KB
Repeat visit
11 KB

98% reduction on repeat visits

Saving 0.12g CO2 per returning visitor

19 resources served from cache · 1 resources re-downloaded

A+
Carbon Budget
10th percentile
PASS
10th percentile
Info::
0.12g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 90% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 10th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.12g

10th percentile

Cleaner than 90% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 80% cleaner ✓
vs Target 76% cleaner ✓
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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