Claude Fable 5 vs GPT-6 Astra: price, scores, context

Side-by-side comparison

Criterion	Claude Fable 5	GPT-6 Astra
Developer	Anthropic	OpenAI
Released	June 9, 2026	September 4, 2026
Capability index	90.8 / 100	94.7 / 100
Input price	$10	$10
Output price	$50	$50
Cost of a typical task	$0.30	$0.30
Context window	1,000,000 tokens	1,050,000 tokens
Maximum output	50,000 tokens	128,000 tokens
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Accepted inputs	text, image, PDF	text, image, PDF
Open weights	No	No
Knowledge cutoff	January 31, 2026	April 30, 2026

What are we comparing?

This comparison pits two frontier models, the ones you pick when quality comes first against each other: Claude Fable 5 and GPT-6 Astra, one from Anthropic, the other from OpenAI. The first dates from June 9, 2026, the second from September 4, 2026.

All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.

What the benchmarks say

On our capability index, Claude Fable 5 scores 90.8 out of 100 and GPT-6 Astra 94.7. GPT-6 Astra leads by 3.9 points.

On the 5 benchmarks reported for both, Claude Fable 5 wins 1 time and GPT-6 Astra 3:

GPQA Diamond (PhD-level science questions): Claude Fable 5 85.9%, GPT-6 Astra 95.8%
OTIS Mock AIME (competition mathematics problems): Claude Fable 5 100%, GPT-6 Astra 100%
FrontierMath (very hard research-level mathematics): Claude Fable 5 87%, GPT-6 Astra 93.7%
FrontierCode (advanced programming tasks): Claude Fable 5 53.5%, GPT-6 Astra 53.3%
APEX-Agents (professional tasks carried out by an agent): Claude Fable 5 63.6%, GPT-6 Astra 64.7%

Pricing

Claude Fable 5 costs $10 per million input tokens and $50 per million output tokens; GPT-6 Astra costs $10 and $50.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.30 with Claude Fable 5 versus $0.30 with GPT-6 Astra. The cost is almost the same.

Run the numbers with your own volumes in the agent cost calculator.

Context and capabilities

GPT-6 Astra reads more in one go: 1,050,000 tokens of context (roughly 1,575 pages), versus 1,000,000 for Claude Fable 5.

Reasoning mode: Claude Fable 5 yes, GPT-6 Astra yes. Tool calling: Claude Fable 5 yes, GPT-6 Astra yes. Image input: Claude Fable 5 yes, GPT-6 Astra yes.

Neither publishes its weights: both are used through an API.

Knowledge cutoff: January 31, 2026 for Claude Fable 5, April 30, 2026 for GPT-6 Astra.

In short

Our reading of the data:

Choose GPT-6 Astra for a higher capability index and a more recent release.

This verdict relies on public figures; it does not replace a trial on your own tasks.

Frequently asked questions

Claude Fable 5 or GPT-6 Astra: which is better?

On our index (Epoch AI data), Claude Fable 5 scores 90.8 and GPT-6 Astra 94.7 out of 100. The best choice also depends on price and on your use case.

Which one is cheaper?

Claude Fable 5. To read 20,000 tokens and write 2,000, expect $0.30 with Claude Fable 5 and $0.30 with GPT-6 Astra (prices as of October 22, 2026).

Which one has the larger context window?

GPT-6 Astra, with 1,050,000 tokens versus 1,000,000.

Can I run Claude Fable 5 or GPT-6 Astra on my own servers?

No: both are closed models, available through an API.

Claude Fable 5 versus GPT-6 Astra