GPT-6 Astra vs Claude Fable 5.1: Flagship Models Compared

GPT-6 Astra and Claude Fable 5.1 occupy the same premium price tier. Both list $10 per million input tokens and $50 per million output tokens. Their published roles overlap, but the details matter: OpenAI pitches Astra for the hardest end-to-end work, while Anthropic calls out demanding reasoning and long-horizon agentic tasks for Fable 5.1.

The benchmark table draws on the published Epoch AI benchmark export and LiveBench task scores. Both models are compared within the same benchmark row. The table updates from structured source snapshots rather than hand-typed article figures; the accent identifies the stronger result for each task.

What do the shared benchmark results show?

Astra leads the current shared results across factual questions, advanced mathematics, deductive reasoning, and spatial assembly. Both models reach the same score on OTIS AIME. These evaluations cover several abilities, but none is a blanket ranking for every coding or agent workflow.

For readers comparing value, the equal token prices simplify the first cut: choose based on the work and the surrounding platform rather than a headline per-token saving. At one million input tokens and one million output tokens, either model’s published base token price totals $60. Tool use and other service charges can change a real bill.

How do their specifications compare?

The figures come from the OpenAI model catalog and Anthropic model overview. Both providers list text and image input, text output, and tool use for these models. Each platform has its own API, tools, and surrounding workflow features, which may matter more than the small difference between their listed context windows.

Which model should you choose?

For a difficult reasoning task where the published math and factual results map to your needs, Astra has the stronger showing in the shared rows. For a long-running agent or research workflow already built around Anthropic’s platform, Fable 5.1 is the direct premium alternative. The most useful decision is the one tied to the task you actually have: compare the evidence for that task, the API features you need, and the price of the full workflow.

If the premium tier is more than your work requires, step down a tier before accepting a $60-per-two-million-token baseline. Compare other current models by price, context, published results and fit.

Frequently asked questions

Is GPT-6 Astra cheaper than Claude Fable 5.1?

Their listed direct API token prices are the same: $10 per million input tokens and $50 per million output tokens. Other platform or tool charges can change the final cost.

Which model has the larger context window?

OpenAI lists 1.05 million tokens for Astra; Anthropic lists 1 million tokens for Fable 5.1. Both list a 128,000-token maximum output.

Which one wins the published benchmarks?

In the current shared Epoch results, Astra leads most rows, including FrontierMath and SimpleQA Verified, while OTIS AIME is tied. Each row measures a specific task and evaluated configuration.