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Claude Fable 5.1 vs Claude Opus 4

Claude Fable 5.1 leads the LLM Stats Score 57.0 to 27.9. Claude Fable 5.1 is 1.5x cheaper per token.

Anthropic · Anthropic · Updated for 2026

Which is better?

Claude Fable 5.1 leads the overall LLM Stats Score 57.0 to 27.9, ranking #1 overall.

On price, Claude Fable 5.1 is roughly 1.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Claude Fable 5.1 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Fable 5.1

  • overall performance matters — it scores 57.0 and ranks #1 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • cost matters — it's about 1.5x cheaper per token
  • you process long inputs — it offers a 1,000,000 token context window
  • you want the most recent training data — it shipped Sep 2026

Choose Claude Opus 4

  • you want predictable pricing at $15.00/M input and $75.00/M output

At a glance

The differences that matter most.

Claude Fable 5.1
Anthropic
Claude Opus 4
Anthropic
Core performance indexes
LLM Stats Score
57.0
#1
27.9
#129
Reasoning
54.5
#4
27.9
#122
Coding
37.0
#17
17.8
#109
Agents
42.2
#1
8.5
#122
Cost, coverage & limits
Benchmark wins
—
—
Input price
$10.00 / M
$15.00 / M
Output price
$50.00 / M
$75.00 / M
Context window
1,000,000
200,000

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Claude Fable 5.1
Claude Opus 4
Vision
40.8#1
11.9#102
Tool use
31.6#8
19.4#57
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

7 reported for Claude Fable 5.1 · 9 for Claude Opus 4

No common benchmarks found

Claude Fable 5.1 and Claude Opus 4don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Claude Fable 5.1 costs less

For input processing, Claude Fable 5.1 ($10.00/1M tokens) is 1.5x cheaper than Claude Opus 4 ($15.00/1M tokens).

For output processing, Claude Fable 5.1 ($50.00/1M tokens) is 1.5x cheaper than Claude Opus 4 ($75.00/1M tokens).

In conclusion, Claude Opus 4 is more expensive than Claude Fable 5.1.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Thu Sep 03 2026 • llm-stats.com
Anthropic
Claude Fable 5.1
Input tokens$10.00
Output tokens$50.00
Best providerAnthropic
Anthropic
Claude Opus 4
Input tokens$15.00
Output tokens$75.00
Best providerAnthropic
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Claude Fable 5.1 accepts 1,000,000 input tokens compared to Claude Opus 4's 200,000 tokens. Claude Fable 5.1 can generate longer responses up to 128,000 tokens, while Claude Opus 4 is limited to 32,000 tokens.

Anthropic
Claude Fable 5.1
Input1,000,000 tokens
Output128,000 tokens
Anthropic
Claude Opus 4
Input200,000 tokens
Output32,000 tokens
Thu Sep 03 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Fable 5.1 and Claude Opus 4 support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Fable 5.1

Text
Images
Audio
Video

Claude Opus 4

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Fable 5.1

Proprietary

Closed source

Claude Opus 4

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Fable 5.1 was released on 2026-09-01, while Claude Opus 4 was released on 2025-05-22.

Claude Fable 5.1 is 16 months newer than Claude Opus 4.

Claude Fable 5.1

Sep 1, 2026

1 days ago

1.3yr newer
Claude Opus 4

May 22, 2025

1.3 years ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Claude Fable 5.1 is available from Anthropic. Claude Opus 4 is available from Anthropic, Bedrock, Google.

Claude Fable 5.1

anthropic logo
Anthropic
Input Price:Input: $10.00/1MOutput Price:Output: $50.00/1M

Claude Opus 4

anthropic logo
Anthropic
Input Price:Input: $15.00/1MOutput Price:Output: $75.00/1M
bedrock logo
AWS Bedrock
Input Price:Input: $15.00/1MOutput Price:Output: $75.00/1M
google logo
Google
Input Price:Input: $15.00/1MOutput Price:Output: $75.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Fable 5.1 and Claude Opus 4 side-by-side, then vote on the output you prefer.

Claude Fable 5.1
✓ Preferred
Claude Opus 4
Open in Playground

FAQ

Common questions about Claude Fable 5.1 vs Claude Opus 4.

Which is better, Claude Fable 5.1 or Claude Opus 4?

Claude Fable 5.1 leads the LLM Stats Score 57.0 to 27.9. Claude Fable 5.1 is made by Anthropic and Claude Opus 4 is made by Anthropic. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Fable 5.1 compare to Claude Opus 4 in benchmarks?

Claude Fable 5.1 scores OSWorld 2.0: 77.9%, CursorBench v3.2: 73.4%, Humanity's Last Exam: 65.0%, GDPval-AA: 61.8%, Terminal-Bench 4.0: 55.8%. Claude Opus 4 scores MMMLU: 88.8%, TAU-bench Retail: 81.4%, GPQA: 79.6%, MMMU (validation): 76.5%, AIME 2025: 75.5%.

Is Claude Fable 5.1 cheaper than Claude Opus 4?

Claude Fable 5.1 is 1.5x cheaper for input tokens. Claude Fable 5.1 costs $10.00/M input and $50.00/M output via anthropic. Claude Opus 4 costs $15.00/M input and $75.00/M output via anthropic.

What are the context window sizes for Claude Fable 5.1 and Claude Opus 4?

Claude Fable 5.1 supports 1.0M tokens and Claude Opus 4 supports 200K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Fable 5.1 and Claude Opus 4?

Key differences include LLM Stats Score (57.0 vs 27.9), context window (1.0M vs 200K), input pricing ($10.00 vs $15.00/M). See the full comparison above for benchmark-by-benchmark results.

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