Has GPT-5.6 been officially released?

OpenAI previewed GPT-5.6 Sol, Terra, and Luna on June 26, 2026 in a limited Codex and API preview. Terminal-Bench 2.1 scores are official; OpenAI will publish an expanded benchmark suite at general availability. Broad ChatGPT access is planned in coming weeks.

Does GPT-5.6 Sol beat Claude Fable 5 on benchmarks?

On Terminal-Bench 2.1, yes — OpenAI reports GPT-5.6 Sol at 88.8% and Sol Ultra at 91.9% versus Claude Fable 5 at 83.4%. On SWE-Bench Pro and other coding benchmarks from before Fable's suspension, Fable 5 still held large leads over GPT-5.5; OpenAI has not yet published GA scores for those evals on Sol.

What are Claude Fable 5's strongest benchmarks?

Claude Fable 5 leads the SWE-Bench Pro leaderboard at 80.3% (vs GPT-5.5's 58.6%), scores 89.78% on LiveCodeBench (first overall), reaches 59.0% on Humanity's Last Exam without tools, and scores 29.3% on FrontierCode Diamond—more than double GPT-5.5's 5.7%.

What is GPT-5.6 expected to improve over GPT-5.5?

GPT-5.6 targets better agentic reasoning, improved multi-hour task completion on Codex Computer Use workloads, a 1.5M token context window, better token efficiency, and stronger performance on FrontierMath Tier 4 (expected to push past 40% from GPT-5.5's 35.4%).

Which model is better for coding in 2026?

Claude Fable 5 currently leads on every major coding benchmark: SWE-Bench Pro (80.3%), LiveCodeBench (89.78%), and FrontierCode Diamond (29.3%). GPT-5.6 is expected to improve on GPT-5.5's 58.6%, but would need extraordinary gains to match Fable 5 on these metrics.

How does pricing compare between the two models?

Claude Fable 5 is priced at approximately $10 per million input tokens and $50 per million output tokens. GPT-5.5 is $5/$30 per million tokens. GPT-5.6 pricing has not been officially announced, but improved token efficiency is expected to partially offset any cost difference.

What is Claude Fable 5's safety approach?

Fable 5 is described as the first Mythos-class model made safe for general public access. It includes an external safety classifier layer rather than capability reduction—meaning full intelligence is available, held in check by classifiers rather than a lobotomized capability ceiling. The restricted Claude Mythos 5 variant (no classifiers) is available only to vetted cyber defenders and biomedical researchers.

Will GPT-5.6 beat Claude Fable 5 overall?

Based on available data, GPT-5.6 will likely close the gap from GPT-5.5 meaningfully, particularly on agentic and long-context tasks. But the 21.7-point SWE-Bench Pro gap and Fable 5's dominance on coding benchmarks suggest GPT-5.6 is more likely to match Fable 5 on specific narrow dimensions than to beat it across the board.

How does pricing compare between the two models?

Claude Fable 5 is priced at approximately $10 per million input tokens and $50 per million output tokens. GPT-5.6 Sol matches GPT-5.5 at $5/$30; Terra is $2.50/$15; Luna is $1/$6. Fable 5 is live globally July 1, 2026.

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GPT-5.6 vs Claude Fable 5: Benchmark Comparison (June 2026 Update)

GPT-5.6 vs Claude Fable 5 benchmarks — July 1, 2026 update. Fable 5 is live again globally. Sol leads Terminal-Bench 2.1; Fable leads SWE-Bench Pro. GPT-5.6 broad GA around the corner.

Jun 17, 2026·0 min read·Yash Thakker

AI ModelsGPT-5.6Claude Fable 5BenchmarksOpenAIAnthropicLLM Comparison

GPT-5.6 vs Claude Fable 5: Benchmark Comparison (June 2026 Update)

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