Claude Fable vs Opus: Which One to Use Now That Fable Pulled Ahead Again

Claude Fable 5.2 beats Claude Opus 5.5 on ten of eleven benchmarks in Anthropic's own launch table, and it costs twice as much per token. That flips the answer to Claude Fable vs Opus back again. From September 22 to November 9, 2026, Opus 5.5 outscored Fable 5.1 almost everywhere at 40% of the price. Fable 5.2, released on November 9, took the lead back and cut Fable's price by 20%. Opus is still where Anthropic tells you to start, but Fable is now a real upgrade rather than a last resort.

Updated 10 November 2026: this comparison now covers Claude Fable 5.2 against Claude Opus 5.5. The earlier version compared Fable 5.1, which Anthropic has moved to its Legacy models list. The history table further down keeps the Fable 5.1 figures.

The independent numbers agree. On the Artificial Analysis Intelligence Index v5.0.1, Fable 5.2 at its Low effort setting scores 53.9 for about $3.10 per task. Opus 5.5 at High scores 51.8 for about $3.46. This guide compares the two on benchmarks, price and plan access. It also shows how the lead has moved since June, explains where Mythos fits, and ends with a simple rule for when Fable is worth paying for.

The Key Takeaways

• Start with Opus: Anthropic's own model guide still says "Most workloads start with Claude Opus 5.5" and moves you to Fable 5.2 when Opus at xhigh or max effort still falls short.
• Price: Opus 5.5 costs $4 / $20 per million input and output tokens. Fable 5.2 costs $8 / $40. Cache reads cost the same, $0.20.
• Plans: Opus is included on Claude Pro. Fable runs on paid usage credits on Pro and is capped at 50% of weekly limits on Max and Ultra.
• Independent score: on Artificial Analysis Intelligence Index v5.0.1, Fable 5.2 leads Opus 5.5 at every effort level, and at Low effort it beats Opus at High for less money per task.
• Mythos: Claude Mythos 5.2 is the same model as Fable 5.2 with different safeguards, open only to organizations Anthropic verifies.

Claude Fable vs Opus at a Glance

Claude Fable 5.2 and Claude Opus 5.5 share the same context window, output limit, knowledge cutoff and speed label. They differ on price and default effort. The table compares the current versions, as listed in Anthropic's model documentation and pricing page.

Fable's premium does not buy a bigger context window or a longer answer. It buys a different model that Anthropic calls its "most capable model open to all customers". Whether that capability shows up in your work is the rest of this guide.

Claude Fable vs Opus Benchmarks: Fable Leads at Every Effort Level

Claude Fable 5.2 scores higher than Claude Opus 5.5 on ten of the eleven general benchmarks Anthropic published at launch, and on the independent Artificial Analysis index at every effort level. The one row it loses is close, and the index adds a cost warning at the top settings.

Anthropic's own benchmark table

Anthropic's Claude Fable 5.2 launch page puts Fable 5.2 ahead of Opus 5.5 on ten of eleven general benchmarks. The table shows the seven that map most directly to everyday work. Both models ran at their highest available effort with safeguards on, except where a cell names a different setting.

The biggest gap is agentic science, where Fable 5.2 leads by almost sixteen points on Terminal-Bench-Science. The smallest is computer use, about two points on OSWorld. Opus 5.5 keeps one half of one row: it wins the Elo half of AA-Briefcase, 1800 to 1785, while Fable 5.2 wins the rubric half of the same test.

The independent read, effort by effort

The Artificial Analysis Intelligence Index v5.0.1 shows Fable 5.2 ahead of Opus 5.5 at all five effort levels, and more expensive per task at each matching level. The Artificial Analysis leaderboard scores each effort level as a separate entry, so the table compares like for like. Figures were read on November 10, 2026.

Three readings matter.

At Low effort, Fable 5.2 beats Opus 5.5 at High and costs about 10% less per task. At Medium, the default in the Claude apps and Claude Code, Fable comes within one point of Opus at Xhigh for under two thirds of the cost. And at the top, Fable 5.2 at Max is the highest-scoring Claude model you can use, but each task costs about $26.54, more than two and a half times Opus at Max. For how the index is built and why versions matter, see our guide to AI benchmarks.

Two head-to-head tests Anthropic ran

Anthropic ran Fable 5.2 and Opus 5.5 through the same setup at launch, and Fable came out ahead. A team of about 1,000 Fable 5.2 agents fully formalized the proof of Fermat's Last Theorem in the Lean language in 30 hours, with minimal human intervention. Opus 5.5, given the same 1,000-agent setup, completed 26% of the formalization in 18 hours.

Anthropic also published accuracy-against-cost charts. On FrontierCode 2.0, Fable 5.2 at High effort scores 45.3%, level with Opus 5.5's best of 45.5%, for roughly half the cost per task. On Humanity's Last Exam, Fable 5.2 at Low effort matches Opus 5.5's best for less than a tenth of the cost. Both are Anthropic's own tests, so treat them as evidence, not proof.

Claude Fable vs Opus Price: Twice the Rate, Same Cache Reads

Claude Fable 5.2 costs twice as much as Claude Opus 5.5 for input and output tokens, and exactly the same for cache reads. The cache-read price matters because cached context makes up most of the bill in long agentic and coding sessions.

The token price is only half of the cost story. The other half is how many tokens each model spends to finish. On the Artificial Analysis index, Fable 5.2 costs between about 1.5 and 3.2 times as much per task as Opus 5.5 at the same effort level, but it reaches a given score at a lower effort setting. On subscriptions, the bill shows up differently. Anthropic's help article on Fable does not say how much of a Pro or Max limit one Fable message uses compared with one Opus message. It says only that Fable models use your limits "faster than other Claude models." The full Fable 5.2 price list, including fast mode, is in our Claude Fable 5.2 launch guide, and our Claude Opus 5.5 launch guide covers the Opus side.

Which Claude Plans Include Fable and Opus

Claude Opus is included on every paid plan, while Claude Fable is a paid add-on on Pro and a capped share of your usage on Max. Neither model is on the Free plan. These rows come from Claude's pricing page and Anthropic's help article on Fable models.

On Pro, the choice is between a model your plan includes and one you pay for by the token, and that settles it for most people.

On Max, Fable draws from the same weekly pool as every other model, so a Fable-heavy week leaves less room for Opus. Fable 5.2, Fable 5.1 and Fable 5 all count toward the same 50% Fable cap. When you reach it, you can keep going on usage credits or switch models. Anthropic gave eligible Pro subscribers a one-time credit when Fable 5 moved to usage credits in July 2026. Its help article says Fable 5.2 and Fable 5.1 were never part of that promotion. For how the five-hour and weekly windows work, read our Claude usage limits guide.

How the Gap Between Claude Fable and Opus Changed Since June

Claude Fable led Claude Opus by almost eight points in June 2026, Opus led from September 22, and Fable took the lead back on November 9. The lead has changed hands four times in five months. The table uses Artificial Analysis Intelligence Index v4.3.2 scores at Max effort for every pair, read on October 16, 2026. That makes the numbers comparable with each other, but they are not the scores the index showed at the time.

Fable 5.2 is not in that table because Artificial Analysis scores it only on the newer Intelligence Index v5.0.1, which reweights the benchmarks and cannot be mixed with v4.3.2. On v5.0.1, Fable 5.2 at Max leads Opus 5.5 at Max by 5.5 points, 64.6 to 59.1. Artificial Analysis ran Fable 5 with Claude Opus 4.8 as the fallback model, the one that completes a task when Fable's safeguards step in.

The price gap moved too. Fable cost $10 / $50 from Claude Fable 5 through Fable 5.1, while Opus stayed at $5 / $25 through Opus 4.8 and Opus 5. Opus 5.5 cut that to $4 / $20, which widened the price ratio to 2.5x. Fable 5.2 cut Fable to $8 / $40 and brought the ratio back to 2x. If you are reading a Fable 5.1 vs Opus 5.5 comparison, its verdict was right in October and is wrong now. Every version is covered in our full Claude model comparison.

Claude Fable vs Mythos: Same Model, Different Safeguards

Claude Fable 5.2 and Claude Mythos 5.2 are the same model with different safeguards. In the words of Anthropic's model guide, Mythos 5.2 "offers the same capabilities only to organizations verified through Anthropic's verification programs, such as the Cyber Verification Program."

Mythos 5.2 is not a stronger tier you can buy. It is Fable 5.2 with fewer restrictions on cyber and biology work. When Fable 5.2 blocks a query in those areas, Claude answers it with Opus 4.8 for cybersecurity and Opus 5 for biology instead. On Anthropic's CVE Rediscovery test, Mythos 5.2 found 89.6% of the advisories against 81.3% for Opus 5.5 with its safeguards off. Opus 5.5 ships with similar safeguards to Fable, so most cybersecurity tasks on Opus 5.5 are also re-routed, to Claude Opus 4.8. Our Fable 5.2 and Mythos 5.2 explainer covers the system card and access programs in full.

When to Use Claude Fable Instead of Opus

Anthropic's own rule has not changed: start on Claude Opus 5.5, and move to Claude Fable 5.2 when Opus at Xhigh or Max effort fails on a task you can check. Its model selection guide says to move to Fable 5.2 if your evals at Xhigh or Max effort "still fall short on demanding reasoning or long-horizon agentic work."

The same guide names Fable's jobs: "Agent sessions that run for hours, multistep deep research, analysis carried through to a finished document, spreadsheet, or deck." For coding, refactoring and enterprise work, the guide points to Opus 5.5. What changed with 5.2 is the cost of moving up. If you already run Opus 5.5 at High or above on the API, the index table shows Fable 5.2 at Low or Medium scoring higher for a similar bill, so test that before raising Opus's effort again.

Fable 5.2 makes sense in three situations. You run long autonomous agent sessions or research jobs where Opus loses track of constraints partway through. You pay by the token and Opus is already running at High effort or above. Or you are on Max or Ultra, Opus has failed at Max effort, and you have Fable allowance left that week. On Pro, each of those cases costs usage credits, so the included Opus is still the sensible default.

A second opinion before you pay for Fable

When an Opus answer looks off, the cheapest check is often a different model, not a pricier Claude. Fello AI puts Claude in one picker next to GPT, Gemini, Grok and DeepSeek on Mac, iPhone and iPad. Ask the same question in the same window. You compare two answers without opening another tab or spending Fable credits. It has a free tier to start.

How to Switch Between Claude Fable and Opus on Mac

In the Claude desktop app on Mac, pick "Fable 5.2" or the Opus model from the model picker. Fable 5.1 and Fable 5 are still listed there too. In Claude Code, Opus 5.5 is the default on Pro, Max, Ultra, Team, Enterprise and the Anthropic API, and you switch to Fable explicitly:

1. Update Claude Code with claude update. Fable 5.2 needs version 2.1.321 or later.
2. Inside a session, type /model fable to switch to Fable 5.2, or /model claude-opus-5-5 to go back to Opus.
3. To start a session on Fable, launch it with claude --model fable.
4. On Pro, the picker shows "Requires usage credits" on the Fable row, and Claude Code asks for consent before a Fable request bills credits.

The fable alias now points to Fable 5.2. On Pro and Max, a claude-fable-5-1 model saved in your settings moves to that alias the first time you run version 2.1.321 or later. Typing /model with a name also saves it as your default for new sessions. To try Fable for one session only, open the picker with /model and press s on the Fable row. If you compare the two, keep the effort level fixed: in Claude Code both default to Medium, while on the API Fable 5.2 defaults to High and Opus 5.5 to Medium. To see how Opus compares with the cheaper Claude class, read Claude Opus vs Sonnet.

The Verdict on Claude Fable vs Opus

Keep Claude Opus 5.5 as your default, and treat Claude Fable 5.2 as the upgrade it is again. Fable 5.2 scores higher on ten of Anthropic's eleven benchmarks and on the independent index at every effort level, and at low effort it can be cheaper per task than Opus at high effort. On Pro, Opus 5.5 is still the strongest Claude model inside your plan.

Move to Fable 5.2 for long agent runs, deep research and hard technical problems, and on the API test it at Low or Medium effort before you push Opus higher. That answer has flipped four times since June and will flip again when Anthropic ships the next Opus (our Claude 6 release date guide covers what is coming and when). Until then, start on Opus, and reach for Fable sooner than you did in October.

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