Claude Fable 5
Claude Fable 5 Guide
Claude Fable 5 is Anthropic’s most capable widely released model, launched June 9, 2026. It is a Mythos-class model made safe for general use — built for the most demanding reasoning, long-horizon agentic work, software engineering, and long-context tasks.
Claude Fable 5 (claude-fable-5) is the new top of Anthropic’s model lineup — positioned above the Opus tier. Anthropic describes it as a Mythos-class model made safe for general use: the same underlying model as the restricted Claude Mythos 5, with safety safeguards that make it suitable for wide release. This page covers what it is, how it compares with Claude Opus 4.8, pricing, access, and best use cases.
Always verify current pricing and availability at platform.claude.com.
What Is Claude Fable 5?
Launched June 9, 2026, Claude Fable 5 is Anthropic’s most capable widely released model. Anthropic reports state-of-the-art performance on nearly all tested benchmarks, with particular strength in software engineering, knowledge work, vision, scientific research, memory, and long-context tasks spanning millions of tokens. It is the first model in Anthropic’s new “Fable” naming — a Mythos-class model whose safeguards make it broadly deployable, while Mythos 5 itself remains restricted to trusted-access partners.
Claude Fable 5 Specs and Pricing
| Property | Claude Fable 5 |
|---|---|
| API model ID | claude-fable-5 |
| Launch date | June 9, 2026 |
| Input price | $10 per MTok |
| Output price | $50 per MTok |
| Prompt caching | $12.50/MTok (5m write) · $20/MTok (1h write) · $1/MTok (read) |
| Batch API (input / output) | $5 / $25 per MTok |
| Context window | 1 million tokens (no long-context premium) |
| Max output | 128,000 tokens |
| Extended thinking | No |
| Adaptive thinking | Yes — always on |
| Sampling parameters | temperature / top_p / top_k not supported (like Opus 4.7+) |
Specs and pricing verified from Anthropic’s official pricing page and model overview, June 2026. Note: Fable 5 uses the tokenizer introduced with Opus 4.7 — the same text produces roughly 30% more tokens than on pre-4.7 models, which matters when projecting costs. Try the Claude API Cost Estimator to model your usage.
Claude Fable 5 vs Opus 4.8
| Dimension | Claude Fable 5 | Claude Opus 4.8 |
|---|---|---|
| Position | Most capable widely released model | Most capable Opus-tier model |
| Standard pricing | $10 / $50 per MTok | $5 / $25 per MTok |
| Context / max output | 1M / 128k tokens | 1M / 128k tokens |
| Thinking | Adaptive, always on | Adaptive, optional |
| Safeguard relationship | Routes some requests to Opus 4.8 | Acts as the fallback model |
| When to choose | Highest available capability | Complex work at half the cost |
Practical rule: if Opus 4.8 already completes your task reliably, Fable 5 mostly buys you headroom — at double the per-token price. Fable 5 earns its cost on the hardest problems: very long-horizon agentic runs, demanding multi-step reasoning, large-scale software engineering, and vision-heavy or research-grade work. Use the Claude Model Selector for a quick recommendation.
Safeguards and the Opus 4.8 Fallback
“Made safe for general use” means Fable 5 ships with safety classifiers that watch for a small set of high-risk request categories — offensive cybersecurity tasks, broad biology and chemistry topics (which Anthropic says it intends to narrow over time), and attempts to distill the model. When a classifier triggers, the request is routed to Claude Opus 4.8 instead of being served by Fable 5. Anthropic reports this happens in under 5% of sessions on average. For most users this is invisible; if you work in security or life-science domains, expect some requests to be answered by Opus 4.8.
Availability: API, Plans, and Usage Credits
- API: Generally available since June 9, 2026 on the Claude API, Claude Platform on AWS, Amazon Bedrock, Vertex AI, and Microsoft Foundry. See the Claude API Guide to get started.
- Subscription plans (staged): From launch through June 22, 2026, Fable 5 is included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost.
- From June 23, 2026: Anthropic says using Fable 5 on subscription plans requires usage credits, unless capacity allows it to extend or restore standard subscription access. This can change — check claude.com/pricing before relying on plan access.
- Plan guidance: See Is Claude AI Free? for how Fable 5 fits into Free, Pro, and Max plans.
Best Use Cases
- Complex reasoning — multi-step analysis where weaker models lose the thread
- Long-horizon agentic coding — extended autonomous engineering runs; see Claude for Coding
- Knowledge work — document-heavy professional workflows, redlining, synthesis
- Vision tasks — demanding image and document understanding
- Long-context workflows — work spanning very large codebases or document sets within the 1M window
- Scientific and research support — at a high level; some biology/chemistry requests route to Opus 4.8 by design
Limitations and Cautions
- Safeguards can route some requests to Opus 4.8 — behavior on those requests follows the fallback model
- Double the per-token cost of Opus 4.8; the newer tokenizer also produces ~30% more tokens than pre-4.7 models
- Subscription-plan access is staged and can change after June 22, 2026
- No manual extended thinking and no sampling parameters (
temperature,top_p,top_k) - Always check official Anthropic/Claude pages before making pricing or access decisions
Frequently Asked Questions
What is Claude Fable 5?
Claude Fable 5 is Anthropic’s most capable widely released model, launched June 9, 2026. It is a Mythos-class model made safe for general use through safety safeguards, positioned above the Opus tier for the most demanding reasoning, agentic, and long-context work.
Is Claude Fable 5 available to everyone?
Via the API, yes — it has been generally available since June 9, 2026. On subscription plans, access is staged: included on Pro, Max, Team, and seat-based Enterprise through June 22, 2026, then requiring usage credits unless Anthropic restores standard access. Check claude.com/pricing for current terms.
What is the Claude Fable 5 API ID?
The API model ID is claude-fable-5. It works on the Claude API, Claude Platform on AWS, Amazon Bedrock, Vertex AI, and Microsoft Foundry.
How much does Claude Fable 5 cost?
API pricing is per million input tokens and per million output tokens — double Claude Opus 4.8. Batch API pricing is / per MTok, and prompt cache reads cost /MTok. Verify at platform.claude.com before making billing decisions.
Is Claude Fable 5 better than Opus 4.8?
Fable 5 is the more capable model — Anthropic reports state-of-the-art results on nearly all tested benchmarks. But Opus 4.8 costs half as much per token and handles most complex reasoning and agentic coding well. Choose Fable 5 when you need the highest available capability; choose Opus 4.8 when cost matters.
What happens when Fable 5 safeguards trigger?
When Fable 5’s safety classifiers detect a high-risk request — offensive cyber tasks, broad biology/chemistry topics, or distillation attempts — the request is routed to Claude Opus 4.8 instead. Anthropic says this happens in under 5% of sessions on average.
Is Fable 5 the same as Mythos 5?
They share the same underlying model. Fable 5 is the widely released version with safeguards; Claude Mythos 5 has some safeguards lifted and is restricted to approved customers in Anthropic’s Project Glasswing trusted-access program.
For the broader model landscape, see the Claude 4 guide and Claude Models Explained.