Anthropic
Claude Fable 5.1
Claude Fable 5.1 is a Anthropic model with 1M context, $10 in / $50 out per million tokens, last verified October 1, 2026. Open weights: no. Public-board scores are linked to the publisher; vendor-only figures stay in the watch-out, not on the board.
Claude Fable 5.1 is Anthropic's model for the most demanding reasoning and long-horizon agentic work at $10/$50 — Anthropic now recommends Opus 5.5 as the default for most workloads.
Recorded profile verification October 1, 2026Individual provider fields may change
| Specification | Claude Fable 5.1 |
|---|---|
| Provider | Anthropic |
| Tier | Frontier |
| Context window | 1M |
| Max output | 128K |
| Input / 1M tokens | $10 |
| Output / 1M tokens | $50 |
| Weights | Closed |
| Parameters | Not verifiedUnverified |
| Reasoning levels | low, medium, high, xhigh, max |
| Modalities | text, image |
| API model id | claude-fable-5-1 |
| Released | September 1, 2026 |
Pricing tiers: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $0.25, versus Fable 5's $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high; knowledge cutoff Jun 2026. Retirement not sooner than September 1, 2027.
Publisher evidence
Published benchmark results
Each result keeps its source date visible. Dates refer to source publication or capture unless the source explicitly states when it measured the result. A missing benchmark is not treated as a zero.
| Benchmark | Score | Source date | Source |
|---|---|---|---|
| Artificial Analysis Intelligence Index [max]Claude Fable 5.1 (max with fallback) | 53 | 2026-10-01 | Artificial Analysis · View source |
| Humanity's Last Exam | 65% | 2026-09-01 | Anthropic Fable 5.1 announcement (vendor, with tools; 60.9 no tools) — Anthropic's later Opus 5.5 table lists 65.6; conflict preserved · View source |
| Terminal-Bench 2.1 | 91.4% | 2026-09-26 | Artificial Analysis Terminal-Bench 2.1 (independent, Terminus 2, max effort) · View source |
| DeepSWE 1.1Cross-provider quotation; Fable harness, effort and experiment date unverifiedCross-model comparability not verified | 67.4% | 2026-09-03 | OpenAI GPT-6 Astra launch table quoting a cross-provider result; not a direct Datacurve row · View source |
Best for
- Frontier agents
- Hardest reasoning work
- Fable 5 workloads at the same price
Watch out
History
Claude Fable 5.1 timeline
Release and status events for this model that passed two-source verification — dated, sourced, and linked.
- Claude Fable 5.1 + Mythos 5.1ReleaseSeptember 1, 2026
Anthropic refreshes its flagship: at launch Fable 5.1 topped the Artificial Analysis Intelligence Index (66 on v4.1.1) at unchanged $10/$50 pricing, with cache reads cut to $0.25; restricted-access Mythos 5.1 arrives alongside.
Anthropic — Claude Fable and Mythos 5.1
Source receipts
Catalog figures for this model were checked against the following sources.
- Claude model overview — whole-profile source check October 1 (accessed 2026-10-01)
- Claude current API pricing, caching and inference geography (accessed 2026-10-01)
- Anthropic pricing — Fable 5.1/Mythos 5.1 $10/$50 (accessed 2026-09-03)
- Anthropic models overview — Fable 5.1 (1M context, 128K output) (accessed 2026-09-03)
- Anthropic — Claude Fable and Mythos 5.1 announcement (accessed 2026-09-26)
- Anthropic models overview — Opus 5.5 default; Fable 5.1 for demanding reasoning (accessed 2026-09-26)
- Anthropic effort documentation (Fable 5.1 selectable effort) (accessed 2026-10-01)
Common questions
Claude Fable 5.1
Answered from the verified figures on this page rather than general guidance.