Claude Fable 5.1
Very strong, but Opus 5.5 ranks higher on most boards for 40% of the price; keep Fable for cases Opus misses.
This product is made by Anthropic, whose Claude models help draft our reviews. How we keep that from tilting a score
Should you use it?
Pick it if
Teams whose hardest long tasks still fail on Opus 5.5 at high effort.
Best for: Teams whose hardest long tasks still fail on Opus 5.5 (Chat models Top 20)
Skip it if
Opus 5.5 at high effort already does what you need, as Anthropic's own guidance says s13; the best non-Anthropic pick is GPT-6.1 Sol.
You give up: Slower than Opus 5.5, 2.5 times its token price, and needs 30-day data retention
The short version
- What this is
- Anthropic's largest generally available model, released 1 Sep 2026, built for long, hard reasoning and agent work.
- Why it matters
- It is Anthropic's largest public model, but the newer Opus 5.5 beats it on most public boards for less.
- Third on arena.ai Agent, fifth on WebDev s1 s4.
- Opus 5.5 ranks higher on most boards at 40% of the token price s3 s8.
- In the app it needs Max from $100/month or Pro usage credits s7.
Good at
Our take
Fable 5.1 is a top model that has been overtaken by a cheaper sibling. It is third on the arena.ai Agent board s1 and fifth on WebDev s4, but Opus 5.5, released three weeks later, ranks above it on both, on Expert, and on the Artificial Analysis index s3 s6, at $4 / $20 per 1M tokens against $10 / $50 s8. On the Agent board it also costs about four times as much per task s2.
Anthropic's own guidance is to start with Opus 5.5 and move to Fable only when Opus at higher effort still falls short s13. We agree: for most people, Fable is not worth its price today.
Scores by job
A score from 0 to 100 per job, against everything available today. Overall 88 across 2 jobs, the average of the job scores.
New to this? What the scores and labels mean
- 0 to 100
- Our score for one job, like writing or coding, compared with everything else out today. 100 is the best available today. For AI models we build it from public data, such as Arena's blind votes and Epoch AI's independent tests; apps and tools are scored on our own checklist. The same tool can score differently for different jobs, and where two likely ranges overlap, we call it a tie.
- Our verdict
- Use it: a top choice for most people. Worth trying: good, and worth a go. Depends: good for some people or one kind of job. Wait: too early to tell, or not out for everyone yet. Skip: something else does the job better.
- First look
- Just released. We say what it is and whether to bother, and give it a score once public results exist.
- No score yet
- None of the public sources we use covers it yet, or the only evidence is from a source whose numbers we can't use, so we describe it in words instead.
- Best buy
- Nothing cheaper scores as well for that job.
- Best free
- The best score for that job that costs nothing, through a free plan or by running on your own computer.
- Pay as you go
- No monthly plan: you pay for each use, usually through a developer account.
- Checked
- The day we last confirmed the score and the price against the sources. Prices change often, so check the date.
- AI model
- The engine underneath, like GPT or Claude. You use it through an app or, if you code, directly.
- Open source
- Free to download and run on your own computer, so nothing leaves your machine.
#8 of the 15 we have scored for this job.
From blind votes (Arena) and independent tests (Epoch AI) · Arena data, CC BY 4.0, Epoch AI data, CC BY 4.0
2 sourcesData read 20 Oct
#3 of the 21 we have scored for this job.
From blind votes (Arena) and independent tests (Epoch AI) · Arena data, CC BY 4.0, Epoch AI data, CC BY 4.0
1 source so farData read 20 Oct
#3 in Arena's blind votes for agents. Those votes give a rank but no rating, so there is no score yet.
#3 in Arena's blind votes for agents (rank only, no score yet) · Arena data, CC BY 4.0
2 sourcesData read 20 Oct
Alternatives
Better or cheaper for agents, from our scores, then the ones we'd also look at. The same kind of product comes first.
- Claude Opus 5.5BetterText model#1$20 a monthRanked #1 on Arena's Agent board in agents, against #3 here; $20 a month. Ranks higher on our main boards and costs $4 / $20 against $10 / $50. Side by side
- MiMo-V2.6-ProFreeText model#13FreeRanked #13 on Arena's Agent board in agents, with a free plan. Side by side
- Claude Sonnet 5.5Text model#5$20 a monthRanks above Fable on WebDev for a fifth of the token price. Side by side
Value for money
Where it sits in agents: higher is a better score, further left is cheaper. Green dots are the Best buys.
Evidence
Everything behind the call and the scores, folded so the page stays short. Spotted a wrong price, score or link? Report a mistake.
How we scored this
The research and coding scores are our own, built from public data: blind votes on Arena and, where they cover the job, Epoch AI's independent tests. How we combine them is our method and we don't publish it. For agents, Arena's blind votes give a rank but no rating, so we show the rank and no score yet.
Public leaderboardIndependent test
This product is made by Anthropic, whose Claude models help draft our reviews.
Reviews are drafted with help from AI models, including Anthropic's Claude. Model scores come only from outside leaderboards and independent evaluations, by a written rule.
No one paid for this review or gave us free access, and we earn nothing if you sign up. How we score
Sources 13
- s1arena.ai Agent leaderboard
- s2arena.ai Agent Pareto and cost per task
- s3Artificial Analysis LLM leaderboard
- s4arena.ai Code Arena: WebDev leaderboard
- s5arena.ai Text: Coding leaderboard
- s6arena.ai Text: Expert leaderboard
- s7Claude plans and pricing
- s8Claude API pricing
- s9Claude privacy: is my data used for model training (consumer)
- s10Claude privacy: is my data used for model training (commercial)
- s11arena.ai Text: Creative Writing leaderboard
- s12Claude Fable 5.1 model overview
- s13Claude models overview
Something here out of date or wrong? Report a mistake and we will check it against the source.
History 3 changes
Every change to a rating, the price or our call, with the reason. Scores are against what exists on the day, so they drift down as better things ship. Older entries come from before we moved to scores.
- New: Agents ratedNew: Coding ratedNew: Research ratedReviewed: agents, coding, research.
- Audit: removed an unsourced 'Mythos-class' claim from why; Agent cost relabelled as the 14-day median. Ratings unchanged.
- Worse: Research downNew tie rule: models tied on the Artificial Analysis index take the lowest rank in the tie, so research is rated on that.
Use it well 4 guides on this site
Pages on this site that help with the jobs above.