Claude Fable 5.1 vs GPT-6 Astra

A side-by-side look at Claude Fable 5.1 from Anthropic and GPT-6 Astra from OpenAI: list prices, context windows, licensing and capabilities, with monthly costs worked out for three common workloads.

Data checked October 10, 2026Open in the compare tool

The short version

Price: effectively tied on blended list price.
Larger context window: GPT-6 Astra (1.05M vs 1M tokens).
Inputs: Claude Fable 5.1 accepts text, images, pdf; GPT-6 Astra accepts text, images.
Newer release: GPT-6 Astra (September 3, 2026).

Specs side by side

	Claude Fable 5.1	GPT-6 Astra
Provider	Anthropic	OpenAI
Released	Sep 1, 2026	Sep 3, 2026
Status	Current	Current
Weights and license	Closed Proprietary	Closed Proprietary
Tier	Frontier	Frontier
Context window	1M	1.05M
Max output	125K	125K
Input per 1M tokens	$10	$10
Output per 1M tokens	$50	$50
Cached input per 1M	$0.25	$1
Input types	Text, Images, PDF	Text, Images
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Parameters	Undisclosed	Undisclosed

Highlighted cells are better on that line: lower price or larger limit. List prices, standard tier, checked October 10, 2026.

What they cost for real workloads

Workload (monthly)	Claude Fable 5.1	GPT-6 Astra
Support chatbot30,000 conversations a month, 2,000 input and 400 output tokens each	$1,200	$1,200
Document summaries2,000 documents a month, 12,000 input and 800 output tokens each	$320	$320
Coding agent1,000 tasks a month, 60,000 input and 6,000 output tokens each	$900	$900

Standard rates without caching or batch discounts. Try your own volumes.

Choose Claude Fable 5.1 if

your inputs include pdf
1M-token context window and 128K-token output limit
adaptive thinking is always on, with high effort by default

Choose GPT-6 Astra if

you need more than 1M tokens of context in one request
1.05M-token context window and 128K-token output limit
reasoning effort from low to max

Our take

Both are positioned for agents, coding, long documents. On list price the gap is about 1.0×, which matters most for high-volume, input-heavy workloads. Quality differences shift with every release, so treat this page as a shortlist tool: run 20-50 of your real tasks through both, score the outputs, and divide the bill by the number of tasks each one got right.

Read the full profiles: Claude Fable 5.1 and GPT-6 Astra. For help designing that test, see how to read LLM benchmarks.

Frequently asked questions

Which is cheaper, Claude Fable 5.1 or GPT-6 Astra?

GPT-6 Astra has the lower list price: $10 input and $50 output per million tokens, versus $10 and $50. Discounts for caching and batch processing can change the real bill, so price your own token mix.

Which has the bigger context window?

GPT-6 Astra accepts 1.05M tokens, compared with 1M for Claude Fable 5.1.

Can I run Claude Fable 5.1 or GPT-6 Astra on my own hardware?

Claude Fable 5.1 is closed, so only through hosted APIs. GPT-6 Astra is closed, so only through hosted APIs.

Is Claude Fable 5.1 better than GPT-6 Astra?

It depends on the task. Public benchmarks and arena rankings move with every release and rarely match a specific workload. Use the specs here to shortlist, then test both on your own prompts and compare accuracy, latency and cost per correct answer.

Still choosing a model?

Send us your use case and constraints. We'll come back with a shortlist and an evaluation plan you can run on your own data.

Free and vendor-neutral: no model provider pays for placement.
Your details go only to partners you agree to.