Claude Fable 5.1
Anthropic's top-tier model for demanding reasoning and long-horizon agentic work, at $10 / $50 per million tokens.
What it is
Claude Fable 5.1 extends Claude Fable 5 at the same input and output prices, with cache reads cut to a quarter of the previous cost. Anthropic positions it above Opus 5.5: use it for demanding reasoning and long-horizon agentic work, or when Opus 5.5 at higher effort still falls short on your evals. Claude Mythos 5.1 is the same model restricted to verified organizations.
Pricing
| Input | $10.00 |
| Output | $50.00 |
| Cached input (cache read) | $0.250 |
| Cache write | $12.50 |
| Batch input | $5.00 |
| Batch output | $25.00 |
| Fast / priority input | not published |
| Fast / priority output | not published |
- Cache read is 2.5% of input price (0.025x), the lowest ratio in Anthropic's lineup.
- 1-hour cache write is $20 / MTok.
- No fast mode listed for Fable 5.1.
- Full 1M context at standard price.
Capability highlights
- Stronger long-running agentic coding, multistep research, and document, spreadsheet and slide work than Fable 5 (vendor claim).
- Cache reads at $0.25 / MTok, down from $1 on Fable 5.
- Per-message effort changes, turn-scoped system messages and progress updates between tool calls (all beta).
- Comparative latency: slower than Opus 5.5 and Sonnet 5.5.
Modalities: text, image → text. Adaptive thinking, always on; default effort high.
How to use it
API: Claude API model ID claude-fable-5-1; Amazon Bedrock anthropic.claude-fable-5-1; Google Cloud, Microsoft Foundry and Claude Platform on AWS use claude-fable-5-1.
Versus Claude Fable 5
Same $10 / $50 list price; cache reads dropped from $1 to $0.25 per MTok.
| Claude Fable 5 | Fable 5.1 | |
|---|---|---|
| Input / 1M | $10.00 | $10.00 |
| Output / 1M | $50.00 | $50.00 |
| Cached input / 1M | $1.00 | $0.250 |
| Context window | 1M | 1M |
| Max output | 128K | 128K |
Published benchmark numbers
Vendor-reported, quoted from the linked announcement. Not independently verified; different vendors run benchmarks under different settings.
| Benchmark | Fable 5.1 | Comparison in the same source | Source |
|---|---|---|---|
| Terminal-Bench 4.0 | 55.8% | Opus 5.5: 66.4% | Anthropic announcement |
| GDPval-AA v2.1 (Elo) | 1735 | Opus 5.5: 1846 | Anthropic announcement |
| OSWorld 2.1 (partial) | 80.7% | Opus 5.5: 81.8% | Anthropic announcement |
Comparisons
Sources
Every number above comes from one of these pages, read on the date shown. Searched for: fable 5.1, claude fable 5.1.
- Claude Fable 5.1 model page (platform.claude.com) read 2026-10-08
release date, model IDs, context, output, pricing, cutoff, positioning - Anthropic pricing page read 2026-10-08
cache, batch prices - Anthropic announcement: Claude Opus 5.5 (includes Fable 5.1 scores) read 2026-10-08
benchmarks (vendor-reported)