Claude Fable 5.1 vs Gemini 4 Argon: a data-driven comparison

Side-by-side comparison

Criterion	Claude Fable 5.1	Gemini 4 Argon
Developer	Anthropic	Google DeepMind
Released	September 1, 2026	October 13, 2026
Capability index	92.6 / 100	95.3 / 100
Input price	$10	$2
Output price	$50	$10
Cost of a typical task	$0.30	$0.06
Context window	1,000,000 tokens	1,048,576 tokens
Maximum output	128,000 tokens	32,768 tokens
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Accepted inputs	text, image, PDF	text, image, video, audio, PDF
Open weights	No	No
Knowledge cutoff	June 2026	March 2026

The match-up at a glance

This comparison pits two frontier models, the ones you pick when quality comes first against each other: Claude Fable 5.1 and Gemini 4 Argon, one from Anthropic, the other from Google DeepMind. The first dates from September 1, 2026, the second from October 13, 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.

Which one is more capable?

On our capability index, Claude Fable 5.1 scores 92.6 out of 100 and Gemini 4 Argon 95.3. Gemini 4 Argon leads by 2.7 points.

On the 4 benchmarks reported for both, Claude Fable 5.1 wins 2 times and Gemini 4 Argon 1:

OTIS Mock AIME (competition mathematics problems): Claude Fable 5.1 100%, Gemini 4 Argon 100%
FrontierMath (very hard research-level mathematics): Claude Fable 5.1 90.2%, Gemini 4 Argon 86%
FrontierCode (advanced programming tasks): Claude Fable 5.1 50.9%, Gemini 4 Argon 47.6%
APEX-Agents (professional tasks carried out by an agent): Claude Fable 5.1 68.6%, Gemini 4 Argon 82.4%

Budget

Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens; Gemini 4 Argon costs $2 and $10.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.30 with Claude Fable 5.1 versus $0.06 with Gemini 4 Argon. Gemini 4 Argon is 5 times cheaper, a gap that adds up quickly over 1,000 tasks: $240 difference.

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

Features and limits

Gemini 4 Argon reads more in one go: 1,048,576 tokens of context (roughly 1,573 pages), versus 1,000,000 for Claude Fable 5.1.

Reasoning mode: Claude Fable 5.1 yes, Gemini 4 Argon yes. Tool calling: Claude Fable 5.1 yes, Gemini 4 Argon yes. Image input: Claude Fable 5.1 yes, Gemini 4 Argon yes.

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

Knowledge cutoff: June 2026 for Claude Fable 5.1, March 2026 for Gemini 4 Argon.

In short

Our reading of the data:

Choose Gemini 4 Argon for a higher capability index and a lower cost.

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

Frequently asked questions

Claude Fable 5.1 or Gemini 4 Argon: which is better?

On our index (Epoch AI data), Claude Fable 5.1 scores 92.6 and Gemini 4 Argon 95.3 out of 100. The best choice also depends on price and on your use case.

Which one is cheaper?

Gemini 4 Argon. To read 20,000 tokens and write 2,000, expect $0.30 with Claude Fable 5.1 and $0.06 with Gemini 4 Argon (prices as of October 22, 2026).

Which one has the larger context window?

Gemini 4 Argon, with 1,048,576 tokens versus 1,000,000.

Can I run Claude Fable 5.1 or Gemini 4 Argon on my own servers?

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

Claude Fable 5.1 vs Gemini 4 Argon