Fable 5 vs GPT-5.5: A Cross-Vendor Reality Check
| Spec | Claude Fable 5 | GPT-5.5 · OpenAI |
|---|---|---|
| Tier | Mythos-class (above Opus) | Frontier (OpenAI) |
| Availability (general) | Suspended (export-control directive) ↗ | Available |
| Released | June 9, 2026 ↗ | — |
| Context window | 1M tokens | Not tracked here Out of scope; see OpenAI docs. |
| Max output | Up to 128k tokens | — |
| Input price (per M tokens) | $10 / M (after intro window) | — |
| Output price (per M tokens) | $50 / M (after intro window) | — |
| Data retention | 30 days | — |
| Zero-data-retention (ZDR) | No ZDR | — |
| Covered Model | Yes — Covered Model | — |
| Safeguards | Classifiers for cyber, bio/chem, distillation; reroute to Opus 4.8 | — |
| How to access | Claude API, AWS Bedrock, Google Cloud, Microsoft Foundry (when not suspended) | — |
What we can state with confidence
On the Anthropic side, the facts are firm: Fable 5 is the safeguarded, public edition of the June 2026 Mythos-class release, with a 1M-token context, up to 128k output, and $10/$50 per-million pricing after intro. It also wraps classifiers that can reroute flagged sessions to Opus 4.8. Critically, Fable 5 access is currently suspended under an export-control directive.
What we won't pretend to know
GPT-5.5 is OpenAI's product. We include it for orientation, but its precise context window, output limits, and pricing are out of scope here and the auto-generated spec figures for it should be treated as illustrative, not authoritative. For real numbers, go to OpenAI's own model and pricing pages.
How to actually choose
Pick on ecosystem fit, the availability of each model in your region, and your own evaluation harness — not on social-media leaderboards. Any Fable-5-vs-GPT benchmark circulating now is unofficial until Anthropic's system card, and OpenAI's numbers should come from OpenAI.
Frequently asked questions
Which is better, Fable 5 or GPT-5.5?
We can't give an authoritative cross-vendor verdict. Fable 5 is a strong Mythos-class model but currently suspended; GPT-5.5's specs belong to OpenAI. Run your own evaluation.
How much does GPT-5.5 cost?
We don't publish OpenAI pricing — it's out of scope here. Check OpenAI's official pricing page for current GPT-5.5 rates.
Are the GPT-5.5 numbers in the table on this page official?
No. Cross-vendor figures here are illustrative only. Treat OpenAI's own documentation as the source of truth.
Sources & further reading
- Anthropic pricingOfficialanthropic.com
- anthropicmythos.aiFlagshipanthropicmythos.ai
Facts on this page link to their source. Quotes are kept under 15 words and attributed; figures labelled unofficial are third-party until Anthropic publishes system-card numbers.