Fable 5 vs Opus Cheat Sheet

Fable 5 is double the price of Opus and chews through credits. Here is the simple rule for when it is worth it, and when to stay on Opus, so you never waste a run.

What You'll Learn

• The one-line rule for picking Fable 5 vs Opus 4.8
• How to switch models in the desktop app and in Claude Code
• The June 23 pricing change you need to plan around

Read This First

On June 9, 2026 Anthropic released Claude Fable 5, its most powerful model ever made generally available. It sits above Opus 4.8 on nearly every benchmark. But it costs double and runs slower, so it is not a straight upgrade. It is a premium tier you reach for on purpose. This is the simple decision rule so you spend credits where they actually pay off.

The one-line rule: Long, multi-step jobs you can kick off and walk away from: use Fable 5. Quick questions and everyday work: stay on Opus 4.8 at half the price.

What Fable 5 Actually Is

Fable 5 is Anthropic's new flagship. It is built for long-horizon work: it plans across stages, spins up its own sub-agents, runs for hours, and at high effort it checks its own output before handing it back. The team at Every got early access and called it the best coding model in the world, scoring 91 out of 100 on their Senior Engineer benchmark versus Opus 4.8's 63.

• Best at: big coding builds, multi-day projects, agentic workflows, deep research runs
• Not built for: quick questions, small edits, all-day back-and-forth chat
• Personality: patient and thorough, not fast

How To Switch To Fable 5

It is live on the Claude API, claude.ai (Pro, Max, Team, Enterprise), and the major clouds. Switching takes two seconds.

• Desktop or web app: click the model dropdown at the top of the chat and select Fable 5
• Claude Code in the terminal: type /model and pick Fable 5 from the list
• On a safeguarded topic (security, bio, chemistry) it quietly routes that answer to Opus 4.8 for you

Where It Fits: Fable 5 vs Mythos 5

Fable 5 and Mythos 5 are the same underlying model. Mythos 5 is the version with safeguards lifted, restricted to vetted Project Glasswing partners doing cyberdefense and infrastructure work. Fable 5 is that same model with the guardrails on, made safe for the public. You are getting Anthropic's frontier model, with a seatbelt.

The Cost Reality

Fable 5 is $10 per million input tokens and $50 per million output, double Opus 4.8's $5 and $25. A 90 percent prompt-caching discount applies to input, which helps on repeated context. It is slower and more token hungry than Opus, so a careless run gets expensive fast.

June 23 timeline: Fable 5 is free on subscription plans from June 9 to 22. From June 23 it runs off usage credits, then returns to standard plan access once capacity allows. Use the free window to test it on a real project before credits kick in.

How To Actually Run It

Fable 5 rewards a good plan. Do not dump a vague task on it. Write a detailed plan first, point Fable 5 at the plan, and let it run. The better your plan, the more of its long-horizon strength you get.

• Write a clear, step-by-step plan or spec before you start
• Point Fable 5 at the plan and let it run uninterrupted
• Use it for the one big job per week that actually moves the needle, not your daily chat

Go Deeper

Printable PDF version of this guide: https://drive.google.com/file/d/1R94T5LaB0IMJM523Lp9hFB6UmCDhQmTR/view?usp=drivesdk

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