Head-to-head · Anthropic vs OpenAI
Claude Fable 5.1 vs GPT-6 Astra
Quick answer: Claude Fable 5.1 stands out for highest quality ceiling in the generally available Claude lineup. GPT-6 Astra stands out for highest capability OpenAI offers. Reviewed September 2026.
Overview
Claude Fable 5.1: Claude Fable 5.1 is Anthropic's premium generally available model, priced above Opus and built for the hardest reasoning, coding and analysis tasks. Anthropic says the cheaper Opus 5.5 now matches it on most work, so Fable 5.1 makes most sense where the last few points of quality justify the price.
GPT-6 Astra: GPT-6 Astra, released by OpenAI on 3 September 2026, is the company's most capable model to date, with state-of-the-art results on computer use, coding, cybersecurity and science. It sits at the top of the GPT-6 family in both capability and price.
At a glance
| Dimension | Claude Fable 5.1 | GPT-6 Astra |
|---|---|---|
| Vendor | Anthropic | OpenAI |
| Starting price | API: $10 in / $50 out per M tokens | API: $10 in / $50 out per M tokens |
| Pricing model | Paid | Paid |
| Free tier | No | No |
| Category | Generative AI | Generative AI |
Strengths and limits
Claude Fable 5.1
- Highest quality ceiling in the generally available Claude lineup
- Suited to long, high-stakes analysis
- Heavy prompt caching lowers cost for repeated context
Watch out for
- $10 input and $50 output per million tokens
- Opus 5.5 is comparable on most tasks at lower cost
- Not needed for routine work
GPT-6 Astra
- Highest capability OpenAI offers
- Broad strength across coding and agentic work
- Large ecosystem of tools and integrations
Watch out for
- $10 input and $50 output per million tokens
- GPT-6 Sol is far cheaper for most work
- Very new, so long-term evaluations are limited
Key features
Claude Fable 5.1
- 1M-token context window at standard pricing
- Top-tier reasoning and agentic performance
- Cache reads priced at a steep discount for repeated context
- Tool use and computer use
- Available through the Claude API and major clouds
GPT-6 Astra
- Top of the GPT-6 family for capability
- Strong computer use and coding performance
- Advanced cybersecurity and science reasoning
- Available through the OpenAI API
Pricing compared
Claude Fable 5.1 is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
GPT-6 Astra is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Frequently asked questions
Which is better, Claude Fable 5.1 or GPT-6 Astra?
It depends on the work. Claude Fable 5.1 stands out for highest quality ceiling in the generally available Claude lineup. GPT-6 Astra stands out for highest capability OpenAI offers.
How do Claude Fable 5.1 and GPT-6 Astra compare on price?
Claude Fable 5.1 is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing. GPT-6 Astra is priced by usage rather than by seat: API: $10 in / $50 out per M tokens. That means cost scales with how much text you send and receive, so estimate your monthly volume before committing.
Is there a free option between Claude Fable 5.1 and GPT-6 Astra?
Neither lists a permanent free tier. Look for trials or usage-based pricing to test on real work first.