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Claude Fable 5.1 vs Claude Opus 5
Of the 3 public leaderboards that rate both, Claude Fable 5.1 scores higher on 2 and Claude Opus 5 on 1. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Fable 5.1 is at 91.7 and Claude Opus 5 at 74.1 (out of 100). On each maker's API, Claude Fable 5.1 costs $10 / $50 per 1M tokens (input / output) and Claude Opus 5 $5 / $25.
Scores as published by each board; table composed November 7, 2026.
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Leaderboard by leaderboard
| Board | Claude Fable 5.1 | Claude Opus 5 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,745.7 | 1,691.3 | Claude Fable 5.1 |
| SimpleBench AVG@5 % (private set) | 86.6 | 80.6 | Claude Fable 5.1 |
| LLM Stats LLM Stats Score · composite (0-100), their rendered top 15 | 52.8 | 53.4 | Claude Opus 5 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Claude Fable 5.1 is at 89.4 (#4 of 45) and Claude Opus 5 at 86.7 (#6). Claude Fable 5.1 scores higher on 1 of the 2 coding boards that rate both and Claude Opus 5 on 1.
| Coding board | Claude Fable 5.1 | Claude Opus 5 |
|---|---|---|
| LMArena · Coding | 1,529.9 | 1,532.7 |
| Vals Vibe Code Bench | 90.3 | 88.4 |
Claude Fable 5.1 at a glance
- Developer
- Anthropic
- Status
- Live since September 1, 2026
- API price
- $10 input / $50 output per 1M tokens · Anthropic, claude-fable-5-1
- Context window
- 1M tokens
Live - sticker price held at $10/$50, but cache reads cut 75% to $0.25 = ~25% cheaper typical, up to ~45% agentic · 1M ctx · effort low-max.
Claude Fable 5.1 is live — the sticker price never moved, and the cache read fell 75%
2026-09-01 · Claude Fable 5.1 shipped today, alongside Claude Mythos 5.1. Our radar detected it at 17:52:22 UTC and confirmed it on the next sweep 60 seconds later.
Fable 5.1's August window has closed — the market now prices September at 78%, and one claim in the leak can't be checked at all
2026-08-20 · A claim going round today says Fable 5.1 is in pre-release testing, targeted at September, and running inside Anthropic's own products under the Fable 5 name. One part of that is checkable, one part is checkable and slipping, and one part is — by construction — invisible to anything we can measure.
Claude Opus 5 at a glance
- Developer
- Anthropic
- Status
- Live since July 24, 2026
- API price
- $5 input / $25 output per 1M tokens · Anthropic, claude-opus-5
- Context window
- 1M tokens
Live — detected 16:51 UTC Jul 24, alert fired 61s later · superseded by Opus 5.5 on Sep 22 and moved to Anthropic's legacy list; still served at $5/$25, which is now MORE than its successor.
Claude Opus 5 is live — we detected it at 16:51 UTC and had alerts out 61 seconds later
2026-07-24 · Anthropic's Claude Opus 5 went live on the public API today. Our checkers saw the id appear at 16:51:33 UTC, confirmed it on the next 60-second sweep, and the alert blast went out at 16:52:34 — sixty-one seconds from first sighting to inbox.
Claude Fable 5.1 vs Claude Opus 5: quick answers
Which is better, Claude Fable 5.1 or Claude Opus 5?
It depends on what you measure. Of the 3 public leaderboards that rate both, Claude Fable 5.1 scores higher on 2 and Claude Opus 5 on 1. Claude Fable 5.1's widest lead is on SimpleBench; Claude Opus 5's widest lead is on LLM Stats. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Fable 5.1 is at 91.7 and Claude Opus 5 at 74.1 (out of 100).
Which is newer, Claude Fable 5.1 or Claude Opus 5?
Claude Fable 5.1. It went live on September 1, 2026, 39 days after Claude Opus 5 (July 24, 2026).
Which is cheaper, Claude Fable 5.1 or Claude Opus 5?
Claude Opus 5 is cheaper on both input and output. On each vendor's own API, Claude Fable 5.1 is $10 input / $50 output per million tokens and Claude Opus 5 is $5 input / $25 output per million tokens. Prices as published in the models.dev catalog, as of 2026-11-07.
Which has the bigger context window, Claude Fable 5.1 or Claude Opus 5?
Neither. Both take 1M tokens.
How do Claude Fable 5.1 and Claude Opus 5 compare for coding?
On the ArtificialWatch coding index, Claude Fable 5.1 is at 89.4 (#4 of 45) and Claude Opus 5 at 86.7 (#6). Claude Fable 5.1 scores higher on 1 of the 2 coding boards that rate both and Claude Opus 5 on 1.
Who makes Claude Fable 5.1 and Claude Opus 5?
Both are from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed November 7, 2026). Boards measure different things, so raw scores are only comparable within a row.
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Also: the bench index · API pricing · what a workload costs on each · the wire