Model Comparison
Claude Fable 5 vs GPT-5.5 InstantWhich is better in 2026?
Claude Fable 5 significantly outperforms across most benchmarks. GPT-5.5 Instant is 1.8x cheaper per token.
Verdict: Claude Fable 5 vs GPT-5.5 Instant — which is better?
Claude Fable 5 (by Anthropic) and GPT-5.5 Instant (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Claude Fable 5 outperforms in 1 benchmarks (HealthBench Professional), while GPT-5.5 Instant is better at 0 benchmarks. Claude Fable 5 significantly outperforms across most benchmarks.
On price, GPT-5.5 Instant is roughly 1.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Fable 5 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Claude Fable 5 if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Jun 2026
Choose GPT-5.5 Instant if…
- cost matters — it's about 1.8x cheaper per token
Performance Benchmarks
Comparative analysis across standard metrics
Claude Fable 5 outperforms in 1 benchmarks (HealthBench Professional), while GPT-5.5 Instant is better at 0 benchmarks.
Claude Fable 5 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Fable 5 ($10.00/1M tokens) is 2.0x more expensive than GPT-5.5 Instant ($5.00/1M tokens).
For output processing, Claude Fable 5 ($50.00/1M tokens) is 1.7x more expensive than GPT-5.5 Instant ($30.00/1M tokens).
In conclusion, Claude Fable 5 is more expensive than GPT-5.5 Instant.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Fable 5 accepts 1,000,000 input tokens compared to GPT-5.5 Instant's 400,000 tokens. Both models can generate responses up to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both Claude Fable 5 and GPT-5.5 Instant support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Fable 5
GPT-5.5 Instant
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 was released on 2026-06-09, while GPT-5.5 Instant was released on 2026-05-05.
Claude Fable 5 is 1 month newer than GPT-5.5 Instant.
Jun 9, 2026
1 months ago
1mo newerMay 5, 2026
2 months ago
Knowledge Cutoff
When training data ends
GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Claude Fable 5's cutoff date is not specified.
We can confirm GPT-5.5 Instant's training data extends to 2025-08-31, but cannot make a direct comparison without Claude Fable 5's cutoff date.
—
Aug 2025
Provider Availability
Claude Fable 5 is available from Anthropic. GPT-5.5 Instant is available from OpenAI.
Claude Fable 5
GPT-5.5 Instant
Outputs Comparison
Key Takeaways
Claude Fable 5
View detailsAnthropic
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Claude Fable 5 and GPT-5.5 Instant side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Claude Fable 5 vs GPT-5.5 Instant.