Claude Fable 5.1 vs GPT-6 Luna
Claude Fable 5.1 scores higher on the Models at Work leaderboard (80 vs 66 out of 100). GPT-6 Luna is about 100× cheaper per blended million tokens ($0.20 vs $20). On Artificial Analysis' independent Intelligence Index, Claude Fable 5.1 leads 53 to 38.
| Claude Fable 5.1 · Anthropic | GPT-6 Luna · OpenAI | |
|---|---|---|
| Leaderboard rank | #6 | #10 |
| Score (0–100) | 80 | 66 |
| Tier | Frontier | Fast and cheap |
| Price per 1M tokens | $10 in · $50 out | $0.10 in · $0.50 out |
| Context window | 1M | 1M |
| Open weights | No | No |
| Artificial Analysis Intelligence Index | 53 | 38 |
| Arena text score | 1501 | — |
| Humanity's Last Exam, Diamond (Scale) | 51.3 | — |
| Best for | Long-horizon agents, Problems Opus fails on, Demanding reasoning | ChatGPT Free and Go tier, Simple extraction, Cost floors |
Choose Claude Fable 5.1 if…
- you need long-horizon agents
- you need problems opus fails on
- you need demanding reasoning
The specialist: Anthropic's own docs say to reach for it when Opus 5.5 at high effort still falls short, and the price says the same.
Caveats: Ten dollars per million input is the highest in this table alongside Astra.
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.
Questions people ask
Which is better, Claude Fable 5.1 or GPT-6 Luna?
Claude Fable 5.1 scores higher on the Models at Work leaderboard (80 vs 66 out of 100). GPT-6 Luna is about 100× cheaper per blended million tokens ($0.20 vs $20). On Artificial Analysis' independent Intelligence Index, Claude Fable 5.1 leads 53 to 38.
When should I choose Claude Fable 5.1 over GPT-6 Luna?
Choose Claude Fable 5.1 for long-horizon agents, problems opus fails on, demanding reasoning. The specialist: Anthropic's own docs say to reach for it when Opus 5.5 at high effort still falls short, and the price says the same.
When should I choose GPT-6 Luna over Claude Fable 5.1?
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 Fable 5.1 or GPT-6 Luna?
Claude Fable 5.1 costs $10 per million input tokens and $50 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.