Claude Fable 5.1 or GPT-6.1 Sol: which to choose?
Claude Fable 5.1 (Anthropic) and GPT-6.1 Sol (OpenAI) compared point by point: measured performance, pricing, context and capabilities.
Data as of October 22, 2026
Side-by-side comparison
| Criterion | Claude Fable 5.1 | GPT-6.1 Sol |
|---|---|---|
| Developer | Anthropic | OpenAI |
| Released | September 1, 2026 | September 29, 2026 |
| Capability index | 92.6 / 100 | 92.1 / 100 |
| Input price | $10 | $2 |
| Output price | $50 | $10 |
| Cost of a typical task | $0.30 | $0.06 |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Maximum output | 128,000 tokens | 128,000 tokens |
| Reasoning mode | Yes | Yes |
| Tool calling | Yes | Yes |
| Accepted inputs | text, image, PDF | text, image, PDF |
| Open weights | No | No |
| Knowledge cutoff | June 2026 | April 30, 2026 |
Two models head to head
Claude Fable 5.1 and GPT-6.1 Sol are two frontier models, the ones you pick when quality comes first, one from Anthropic, the other from OpenAI. Claude Fable 5.1 was released on September 1, 2026, GPT-6.1 Sol on September 29, 2026.
All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.
What the benchmarks say
On our capability index, Claude Fable 5.1 scores 92.6 out of 100 and GPT-6.1 Sol 92.1. The gap is too small to separate them.
On the 4 benchmarks reported for both, Claude Fable 5.1 wins 2 times and GPT-6.1 Sol 1:
- OTIS Mock AIME (competition mathematics problems): Claude Fable 5.1 100%, GPT-6.1 Sol 100%
- FrontierMath (very hard research-level mathematics): Claude Fable 5.1 90.2%, GPT-6.1 Sol 93.7%
- FrontierCode (advanced programming tasks): Claude Fable 5.1 50.9%, GPT-6.1 Sol 50.2%
- APEX-Agents (professional tasks carried out by an agent): Claude Fable 5.1 68.6%, GPT-6.1 Sol 60%
Budget
Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens; GPT-6.1 Sol costs $2 and $10.
For a typical agent task (read 20,000 tokens, write 2,000), expect $0.30 with Claude Fable 5.1 versus $0.06 with GPT-6.1 Sol. GPT-6.1 Sol is 5 times cheaper, a gap that adds up quickly over 1,000 tasks: $240 difference.
Run the numbers with your own volumes in the agent cost calculator.
Context and capabilities
GPT-6.1 Sol reads more in one go: 1,050,000 tokens of context (roughly 1,575 pages), versus 1,000,000 for Claude Fable 5.1.
Reasoning mode: Claude Fable 5.1 yes, GPT-6.1 Sol yes. Tool calling: Claude Fable 5.1 yes, GPT-6.1 Sol yes. Image input: Claude Fable 5.1 yes, GPT-6.1 Sol yes.
Neither publishes its weights: both are used through an API.
Knowledge cutoff: June 2026 for Claude Fable 5.1, April 30, 2026 for GPT-6.1 Sol.
In short
Our reading of the data:
- Choose GPT-6.1 Sol for a lower cost.
This verdict relies on public figures; it does not replace a trial on your own tasks.
Other comparisons
Frequently asked questions
Claude Fable 5.1 or GPT-6.1 Sol: which is better?
On our index (Epoch AI data), Claude Fable 5.1 scores 92.6 and GPT-6.1 Sol 92.1 out of 100. The best choice also depends on price and on your use case.
Which one is cheaper?
GPT-6.1 Sol. To read 20,000 tokens and write 2,000, expect $0.30 with Claude Fable 5.1 and $0.06 with GPT-6.1 Sol (prices as of October 22, 2026).
Which one has the larger context window?
GPT-6.1 Sol, with 1,050,000 tokens versus 1,000,000.
Can I run Claude Fable 5.1 or GPT-6.1 Sol on my own servers?
No: both are closed models, available through an API.
Data sources
- Models.dev — Model data: models.dev (open-source project)
- OpenRouter — Market prices cross-checked with OpenRouter
- Epoch AI — AI Benchmarking Hub — Epoch AI, “AI Benchmarking Hub”, epoch.ai, CC BY 4.0
Data as of October 22, 2026
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