For the first time in a while, the two most powerful AI models on the market cost exactly the same, launched within days of each other, and are aimed at overlapping jobs. OpenAI’s GPT-6 Astra and Anthropic’s Claude Fable 5.1 both sit at $10 per million input tokens and $50 per million output, which strips price out of the decision and puts the whole question on capability and fit. Here is how to choose between them.
The headline specs, side by side
| GPT-6 Astra | Claude Fable 5.1 | |
|---|---|---|
| Launched | 3 September 2026 | 1 September 2026 |
| Price (in / out per M) | $10 / $50 | $10 / $50 |
| Context window | ~1.05 million tokens | ~1 million tokens |
| Pitched at | Computer use, browsing, coding, science | Agentic work, coding, top raw intelligence |
| Notable extra | Astra / Astra Pro tiers, Apr 2026 cutoff | 75% cheaper cache reads than launch |
Where each one leans
GPT-6 Astra is explicitly built for computer use and browsing, the “go off and operate software for me” category, alongside coding and science. If your work is agentic tasks that drive a browser or a computer, that is the design intent, and OpenAI’s tooling and ecosystem around agents is deep. Claude Fable 5.1 has been the model to beat on raw measured intelligence and on code that has to follow instructions precisely across long outputs, and its cheaper cache reads genuinely lower the cost of long-running, repetitive agent workflows despite the same headline price.
The cost nuance the sticker hides
Same $10/$50 does not mean same bill. Fable 5.1’s 75% cheaper cache reads matter a lot if your workload sends the same context repeatedly, which most agent and document workflows do; you can pay materially less for the same job even at identical list pricing. Astra, meanwhile, will live or die on how efficiently it completes agentic tasks, since a model that needs fewer steps to finish costs less in practice regardless of the per-token number. Test both on your real workload and watch the total, not the rate card.
How to actually choose
Do not pick on the launch-day benchmarks; pick on your task. If your core need is autonomous computer use and browsing, start with GPT-6 Astra. If it is the hardest reasoning, precise instruction-following, or long document and code work where cache reuse saves money, start with Fable 5.1. Run the same three real jobs through each, judge the output quality and the total cost, and let that decide. At identical pricing, there is no penalty for choosing on merit.
What this means
The flagship race has moved from price to performance, which is good for buyers: two elite models at the same cost, forcing each other to be better. For most people neither is the right daily driver, since a cheaper model handles routine work, but when a task genuinely needs the top tier, you now have two credible options at one price. Choose GPT-6 Astra for agentic computer use, Fable 5.1 for hardest-reasoning and cost-efficient long context, and always verify on your own work before you commit. (Prices as of early September 2026.)
Related on Top Tool Stack: GPT-6 Astra, explained · ChatGPT vs Claude vs Gemini
Did you know: two models at the identical $10/$50 price can still cost you very different amounts, because cheaper cache reads and fewer steps to finish a task change the real bill far more than the sticker rate.