Claude Fable 5.1 vs GPT-6 Astra
Pick two to four models to compare benchmark scores, prices, context windows and speed. The link updates as you pick, so you can share the exact comparison.
Cheapest blended
Claude Fable 5.1GPT-6 Astra
Tie at $20.00 / 1M tokens
Largest context
GPT-6 Astra
1.05M tokens
Fastest output
Claude Fable 5.1
68 tokens/s
Top on Terminal-Bench 4.0
GPT-6 Astra
57.9%
Specifications
| Spec | Claude Fable 5.1Anthropic | GPT-6 AstraOpenAI |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | 1 Sep 2026 | 3 Sep 2026 |
| Licence | Proprietary | Proprietary |
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 128K tokens |
| Input / 1M | $10.00* | $10.00* |
| Output / 1M | $50.00 | $50.00 |
| Cached input / 1M | $0.25 | $1.00 |
| Speed | 68 tokens/s | 51 tokens/s |
| Input types | text, image | text, image |
| Best for | ReasoningAgentsCodingResearch | CodingAgentsReasoningResearch |
* Claude Fable 5.1: Cache reads are 0.025x base input ($0.25), down from $1 on Fable 5. Uses the newer tokenizer (about 30% more tokens than pre-Opus 4.7 models for the same text). Safety classifiers can refuse; since 24 Sep 2026 pre-output refusals in the bio, frontier_llm and reasoning_extraction categories are billed. Minimum cacheable prompt: 512 tokens.
* GPT-6 Astra: Cache writes are 1.25x input; cache reads 0.1x; 30-minute minimum cache life. Batch and Flex: $5 in / $25 out. Fast mode (formerly Priority): 2x, $20 / $100. Ultrafast (Responses API, service_tier "ultrafast", Astra only): $60 in / $6 cached / $75 cache write / $300 out. Data residency endpoints +10%.
Benchmark scores
Officially reported scores only. A model with no published score on a benchmark shows a line, not a zero.
Price per 1M tokens
Context window and speed
Notes
- Claude Fable 5.1
- Anthropic's top generally available model, for demanding reasoning and long-horizon agentic work. Successor to Claude Fable 5 at the same input and output prices, with stronger long-running agentic coding, multistep research and document work.
- GPT-6 Astra
- OpenAI's most capable model, for the hardest end-to-end work: complex reasoning, coding, computer use, research and document creation.
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