Updated for Week 45, 2026

Gemini 4 Carbon vs Claude Opus 5.5

On our Week 45, 2026 scores, Claude Opus 5.5 edges ahead (96 vs 95). But Gemini 4 Carbon is about 2x cheaper on output tokens than Claude Opus 5.5. If cost matters more than the last few points of quality, Gemini 4 Carbon is the smarter buy. Pick Gemini 4 Carbon for security research and vulnerability work, once you can get access. Pick Claude Opus 5.5 for agentic coding.

Gemini 4 CarbonClaude Opus 5.5
MakerGoogleAnthropic
ReleasedOctober 28, 2026September 22, 2026
Price / 1M tokens$2 in / $10 out$4 in / $20 out
Open weightsNoNo
Power Rankings rank#2 (95)#1 (96)
Coding rank#5 (90)#1 (98)
Best for
  • Security research and vulnerability work, once you can get access
  • Hard reasoning and long multi-step tasks
  • Teams already on Gemini who can wait for the wider rollout
  • Agentic coding
  • Long, multi-step knowledge work
  • Writing and analysis
Strengths
  • #1 on Arena text at launch (1528), ahead of Argon (1520) and Claude Opus 5.5 (1509)
  • 59 on the Artificial Analysis Intelligence Index v5, one point above Opus 5.5
  • Cheaper per index task than Opus 5.5 in Artificial Analysis's testing (about $7.76 vs $10.04)
  • Led six of the nine benchmarks Anthropic published at launch
  • 66.4% on Terminal-Bench 4.0 at extra-high effort
  • Much cheaper than the Fable/Mythos tier
Watch out for
  • No API, AI Studio or Gemini app access for the public yet, and no date
  • #4 on Arena WebDev, behind Claude Opus 5.5
  • Google's cybersecurity benchmark scores ran without guardrails and haven't been reproduced independently
  • Trails GPT-6 Astra on AutomationBench and Terminal-Bench-Science
  • Higher effort settings cost more tokens

The short version

Gemini 4 Carbon: Google's second Gemini 4 model, announced October 28, four weeks after Argon was announced. It debuted at #1 on Arena's text leaderboard and on Artificial Analysis's Intelligence Index v5, but at launch only selected cybersecurity defenders in Google's Fairwind Program can use it.

Claude Opus 5.5: Anthropic's new default flagship. Opus 5.5 replaced Opus 5, costs 20% less, and at launch took the top spot on the independent Artificial Analysis Intelligence Index.

Rankings change every week. Check the latest standings or swap in a different model.