Claude Opus 5.5 vs GPT-6 Luna
Claude Opus 5.5 scores higher on the Models at Work leaderboard (91 vs 66 out of 100). GPT-6 Luna is about 40× cheaper per blended million tokens ($0.20 vs $8). On Artificial Analysis' independent Intelligence Index, Claude Opus 5.5 leads 58 to 38.
| Claude Opus 5.5 · Anthropic | GPT-6 Luna · OpenAI | |
|---|---|---|
| Leaderboard rank | #1 | #10 |
| Score (0–100) | 91 | 66 |
| Tier | Frontier | Fast and cheap |
| Price per 1M tokens | $4 in · $20 out | $0.10 in · $0.50 out |
| Context window | 1M | 1M |
| Open weights | No | No |
| Artificial Analysis Intelligence Index | 58 | 38 |
| Arena text score | 1507 | — |
| Humanity's Last Exam, Diamond (Scale) | 55.0 | — |
| Epoch Capabilities Index | 167 | — |
| Best for | Agentic coding, Long-running agents, Enterprise knowledge work | ChatGPT Free and Go tier, Simple extraction, Cost floors |
Choose Claude Opus 5.5 if…
- you need agentic coding
- you need long-running agents
- you need enterprise knowledge work
The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
Caveats: Arena puts Gemini 4 Argon ahead on chat preference; the gap is inside two scores' error bars.
Choose GPT-6 Luna if…
- you need chatgpt free and go tier
- you need simple extraction
- you need cost floors
OpenAI's ten-cent model: the one every ChatGPT Free user now has, and the one Haiku users keep comparing themselves to.
What practitioners say
Claude Opus 5.5: The launch thread was the biggest Claude thread of the year on Hacker News, a port of the TypeScript compiler to Rust credited the model with a working build in ten hours, and a Vals AI materials-discovery run used it for agentic simulation. A 'has it been nerfed yet' tracker is the most-upvoted scepticism.
Questions people ask
Which is better, Claude Opus 5.5 or GPT-6 Luna?
Claude Opus 5.5 scores higher on the Models at Work leaderboard (91 vs 66 out of 100). GPT-6 Luna is about 40× cheaper per blended million tokens ($0.20 vs $8). On Artificial Analysis' independent Intelligence Index, Claude Opus 5.5 leads 58 to 38.
When should I choose Claude Opus 5.5 over GPT-6 Luna?
Choose Claude Opus 5.5 for agentic coding, long-running agents, enterprise knowledge work. The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
When should I choose GPT-6 Luna over Claude Opus 5.5?
Choose GPT-6 Luna for chatgpt free and go tier, simple extraction, cost floors. OpenAI's ten-cent model: the one every ChatGPT Free user now has, and the one Haiku users keep comparing themselves to.
Which is cheaper, Claude Opus 5.5 or GPT-6 Luna?
Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens on Anthropic's list price (Claude pricing, read Oct 10, 2026). GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens on OpenAI's list price (OpenAI API pricing, read Oct 10, 2026).
Scores come from the Models at Work leaderboard: Score is 0 to 100: 50% independent evals normalised within this table, 20% price-performance, 15% practitioner sentiment from Signals and community threads, 15% operational fit (context, speed, availability, open weights). Models within three points are a tie in practice. Vendor-published figures are labelled as such and never counted as independent. Prices are vendor list prices where published; blended figures assume three input tokens per output token.