claude.ai/login

The numbers

First visit

0.936 g CO₂e

Return visit

0.022 g CO₂e

Hosting

unknown

LCP

1.32 s

CLS

n/a

TTFB

15 ms

At 10,000 views a month this page emits about 84.9 kg CO₂e a year, roughly 348 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 2%, and world-average grid intensity. How we calculate this

1. Audit third-party servicessave ~0.271 g/visit (2.42 MB)High impact · moderate effort

   9 third-party domains account for 4.85 MB (77% of the page).

   Remove services that no longer earn their place; load the rest on interaction (facades for embeds, delayed consent-gated tags). Each third party is also a privacy and performance dependency.

   • assets-proxy.anthropic.com3.83 MB
   • newassets.hcaptcha.com801 kB
   • accounts.google.com99 kB
   • js.hcaptcha.com96 kB
   • s-cdn.anthropic.com20 kB
   • bacf1c5c71f9.w.hcaptcha.com3.3 kB

   WSG 3.5: Treat third parties the same as first parties
2. Reduce JavaScript payloadsave ~0.110 g/visit (986 kB)High impact · moderate effort

   85 scripts total 3.94 MB on the wire (13.33 MB decoded). Bundles this size usually carry a lot of unused code.

   Split bundles per route, tree-shake dependencies, and audit with a bundle analyzer or coverage profile. A 25% cut is a conservative target for bundles this size.

   • hsw.js434 kB
   • shared-8-DHdiwlJk.js154 kB
   • shared-5-OtCgloBv.js150 kB
   • shared-7-CK_2LAlI.js144 kB
   • shared-13-CK7YX63u.js143 kB

   WSG 3.2: Minify and remove unused codeWSG 3.3: Modularize bandwidth-heavy components
3. Defer video and audiosave ~0.107 g/visit (953 kB)High impact · quick fix

   1.19 MB of audio/video downloads during initial page load; 1 video autoplays.

   Never autoload media: use preload="none" with a poster image, load players on interaction, and stream in an efficient codec (AV1/HEVC).

   • login-hero-kt3-932d39be.mp41.19 MB

   WSG 2.9: Optimize media to reduce resource use
4. Optimize web fontssave ~0.015 g/visit (132 kB)Medium impact · quick fix

   3 font files total 377 kB.

   Subset fonts to used glyphs, prefer one variable font over multiple weights, serve WOFF2 only, and consider system fonts for UI text.

   • c66fc489e-2VcCjn5t.woff2166 kB
   • cc27851ad-DDVos-BJ.woff2119 kB
   • c0f671921-_JGacpB2.woff292 kB

   WSG 2.11: Use optimized web typography
5. Fix caching for returning visitorssave ~0.0041 g/visit (28 kB)Medium impact · quick fix

   On a repeat visit 111 kB of static assets were re-downloaded instead of coming from cache.

   Serve static assets with Cache-Control: public, max-age=31536000, immutable and versioned filenames so returning visitors download almost nothing.

   • v1Cache-Control: private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0 · 80 kB
   • api.jsCache-Control: max-age=31536000, stale-if-error=10800, stale-while-revalidate=31536000, public · 27 kB
   • favicon.icoCache-Control: public, max-age=0, must-revalidate · 4.8 kB

   WSG 4.2: Optimize caching and support offline access
6. Verify your hosting energyMedium impact · moderate effort

   This host has not published renewable energy evidence with the Green Web Foundation, so its energy source is unknown.

   Choose a provider listed in the Green Web Directory, or ask your current provider to publish evidence (and a carbon.txt). This cuts the data-center share of every single page view.

   • carbon.txtThe host publishes a carbon.txt; its evidence has not reached the Green Web Foundation dataset yet.

   WSG 4.1: Use sustainable hosting
7. Collapse the redirect chainMedium impact · quick fix

   The address that was scanned goes through 3 redirects before the document is served, ending at https://claude.ai/login. Every hop is a full round trip on a connection that has not warmed up yet.

   Point links, sitemaps and canonical tags at the final address, and make the host redirect in one hop rather than chaining http to https to www.

   • https://claude.ai/redirects to https://claude.ai/login

   WSG 4.4: Setup necessary error pages and redirection links
8. Stop downloading the same asset twicesave ~0.010 g/visit (92 kB)Advisory · quick fix

   1 asset was fetched more than once in a single page load (183 kB of repeated transfer).

   Usually a script injected twice or cache-busting query strings that differ per reference. Load each asset once and let the HTTP cache do its job.

   • hcaptcha.html2 downloads · 367 kB

   WSG 3.2: Minify and remove unused code
9. Upgrade compression beyond gzipsave ~0.0093 g/visit (83 kB)Advisory · quick fix

   553 kB of text ships gzip-compressed; Brotli or Zstandard would cut roughly another 15-20%, and browsers without them fall back to gzip automatically.

   Serve precompressed Brotli for static text assets (highest level, compressed at build time) and enable Brotli or zstd for dynamic responses; keep gzip only as the fallback.

   • hsw.js434 kB
   • client99 kB
   • s.js20 kB

   WSG 4.3: Reduce data transfer with compression
10. Set a page-weight budgetAdvisory · moderate effort

    At 6.31 MB per view this page rates F. The findings above list where the weight is.

    Agree a transfer budget (e.g. under 975 kB reaches a B), enforce it in CI, and re-scan after each change to hold the line.

    WSG 3.1: Set goals based on performance and energy impact

Where the bytes are

• JavaScript3.94 MB · 85 req
• Audio / video1.19 MB · 1 req
• HTML389 kB · 3 req
• Fonts377 kB · 3 req
• Images237 kB · 4 req
• CSS164 kB · 17 req
• Data (fetch)9.2 kB · 4 req
• Data (XHR)2.3 kB · 2 req