Gemini 4 Argon
Claude Opus 5.5
Muse Wonder
MiMo-V2.6-Pro
Qwen3.8-Max
Kimi K3
GLM-5.3
GPT-5.5
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DeepSeek-V4.1-Flash-20260910
Grok 4.20 Beta
amazon-nova-experimental-chat
Dola Seed 2.0 Pro
NVIDIA-Nemotron-3-Ultra-550B-A55B
Gemma 4 31B
Step 5 PreviewClaude Opus 5.5 vs Claude Opus 5
- Claude Opus 5.5 rates higher on LMArena’s text leaderboard: 1516 against 1508.
- Claude Opus 5.5 is cheaper: $4 / $20 per million input / output tokens, against $5 / $25 for Claude Opus 5.
- On the 6 Vals AI benchmarks both have taken, Claude Opus 5.5 wins 4 and Claude Opus 5 wins 2 (Claude Opus 5.5: Terminal-Bench 4.0, Vibe Code Bench, Tax Agent Bench).
Side by side
Models (2/6)
- Claude Opus 5.5
- Claude Opus 5
| Benchmark | Claude Opus 5.5 | Claude Opus 5 |
|---|---|---|
| The model | ||
| Lab | Anthropic | Anthropic |
| Released | 2026-09-22 | 2026-07-24 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Input, per 1M tokens | $4 | $5 |
| Output, per 1M tokens | $20 | $25 |
| LMArena, people’s votes | ||
| LMArena TextMillions of people compare two anonymous models side by side and vote for the better answer | 1516#2 of 351 | 1508#4 of 351 |
| LMArena WebDevPeople ask two anonymous models to build the same web app, try both and vote for the better one | 1807#1 of 124 | 1691#9 of 124 |
| LMArena VisionSide-by-side votes on prompts that include an image | 1321#2 of 146 | 1320#3 of 146 |
| LMArena CodingLMArena’s text votes on prompts that ask for code | 1545#1 of 346 | 1533#4 of 346 |
| LMArena MathLMArena’s text votes on math prompts | 1518#6 of 339 | 1533#2 of 339 |
| LMArena Creative writingLMArena’s text votes on stories, poems and other creative writing | 1534#1 of 349 | 1495#5 of 349 |
| LMArena Hard promptsLMArena’s text votes on the hardest prompts | 1536#2 of 351 | 1527#4 of 351 |
| LMArena Instruction followingLMArena’s text votes on prompts with specific instructions to follow | 1539#1 of 351 | 1518#5 of 351 |
| Vals AI, overall | ||
| Vals IndexVals AI’s headline score | 70.18%#2 of 27 | — |
| Vals AI, coding | ||
| Terminal-Bench 4.0Frontier-difficulty tasks an agent completes in a real terminal | 65.15%#1 of 55 | 53.53%#9 of 55 |
| SWE-benchReal GitHub issues from open-source projects | — | 97.00%#1 of 85 |
| Vibe Code BenchBuilding complete web apps from a plain-language brief, graded on whether the app works | 90.29%#5 of 115 | 88.40%#9 of 115 |
| Code MigrationRewriting working programs in a new language, graded on whether the new program still passes its tests | 81.01%#2 of 28 | — |
| LiveCodeBenchFresh competitive programming problems, collected after models’ training cut-offs to avoid contamination | — | 89.03%#4 of 143 |
| Vals AI, finance | ||
| Finance AgentThe core tasks of a financial analyst, done as an agent with research tools | 67.85%#1 of 31 | — |
| Finance IndexVals AI’s composite of finance tasks | 65.59%#1 of 31 | — |
| Tax Agent BenchAgentic research into US corporate tax questions | 45.57%#3 of 76 | 45.55%#4 of 76 |
| Vals AI, law | ||
| Legal IndexVals AI’s composite of legal tasks | 72.33%#7 of 28 | — |
| Legal Research BenchAgentic US legal research | 50.48%#7 of 85 | 55.29%#2 of 85 |
| Vals AI, medicine | ||
| MedCodeAssigning the right medical billing codes from clinical notes | 49.80%#19 of 107 | 63.57%#1 of 107 |
| Vals AI, reasoning | ||
| GPQA DiamondGraduate-level questions in biology, physics and chemistry that experts answer well and search does not | — | 93.43%#8 of 138 |
| MMLU-ProHarder, reasoning-focused multiple choice across 14 subjects, from law to engineering | — | 91.59%#2 of 138 |
| MMMUCollege-level questions that need both an image and text | — | 89.88%#2 of 93 |
| Terminal-Bench ScienceExpert-written scientific research workflows, run by an agent in a terminal | 47.14%#3 of 42 | 27.14%#9 of 42 |
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Questions
Which is better, Claude Opus 5.5 or Claude Opus 5?
Claude Opus 5.5 rates higher on LMArena’s text leaderboard: 1516 against 1508. Claude Opus 5.5 is cheaper: $4 / $20 per million input / output tokens, against $5 / $25 for Claude Opus 5. On the 6 Vals AI benchmarks both have taken, Claude Opus 5.5 wins 4 and Claude Opus 5 wins 2 (Claude Opus 5.5: Terminal-Bench 4.0, Vibe Code Bench, Tax Agent Bench).
Which is cheaper, Claude Opus 5.5 or Claude Opus 5?
Claude Opus 5.5 is cheaper: $4 / $20 per million input / output tokens, against $5 / $25 for Claude Opus 5.