Claude Fable 5.1 vs GPT-5.4 nano
Claude Fable 5.1 leads the LLM Stats Score 54.5 to 26.6. GPT-5.4 nano is 43.2x cheaper per token.
Anthropic · OpenAI · Updated for 2026
Which is better?
Claude Fable 5.1 leads the overall LLM Stats Score 54.5 to 26.6, ranking #4 overall.
In the 1 individual benchmarks reported for both models, Claude Fable 5.1 wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-5.4 nano is roughly 43.2x 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 54.5 and ranks #4 on LLM Stats
- your work emphasizes reasoning and coding — it leads those capability indexes
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- 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 GPT-5.4 nano
- cost matters — it's about 43.2x cheaper per token
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
7 reported for Claude Fable 5.1 · 15 for GPT-5.4 nano
Claude Fable 5.1 outperforms in 1 benchmarks (Humanity's Last Exam), while GPT-5.4 nano is better at 0 benchmarks.
Claude Fable 5.1 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Fable 5.1 ($10.00/1M tokens) is 50.0x more expensive than GPT-5.4 nano ($0.20/1M tokens).
For output processing, Claude Fable 5.1 ($50.00/1M tokens) is 40.0x more expensive than GPT-5.4 nano ($1.25/1M tokens).
In conclusion, Claude Fable 5.1 is more expensive than GPT-5.4 nano.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Fable 5.1 accepts 1,000,000 input tokens compared to GPT-5.4 nano's 400,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Fable 5.1 and GPT-5.4 nano support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Fable 5.1
GPT-5.4 nano
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Fable 5.1 was released on 2026-09-01, while GPT-5.4 nano was released on 2026-03-17.
Claude Fable 5.1 is 6 months newer than GPT-5.4 nano.
Sep 1, 2026
3 weeks ago
5mo newerMar 17, 2026
6 months ago
Knowledge Cutoff
When training data ends
GPT-5.4 nano has a documented knowledge cutoff of 2025-08-31, while Claude Fable 5.1's cutoff date is not specified.
We can confirm GPT-5.4 nano's training data extends to 2025-08-31, but cannot make a direct comparison without Claude Fable 5.1's cutoff date.
—
Aug 2025
Provider Availability
Claude Fable 5.1 is available from Anthropic. GPT-5.4 nano is available from OpenAI.
Claude Fable 5.1
GPT-5.4 nano
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Fable 5.1 and GPT-5.4 nano side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Fable 5.1 vs GPT-5.4 nano.