By the toolist.ai editors. Researched from public sources, not hands-on tested by toolist.ai. Updated October 6, 2026; prices checked October 6, 2026.
Claude Opus 5.5 vs Claude Fable 5.1
Verdict
Start with Claude Opus 5.5. It costs 60% less per token than Claude Fable 5.1 ($4 and $20 against $10 and $50), scores higher on seven of the eight Artificial Analysis benchmarks both have and ties the eighth. Anthropic itself recommends Opus 5.5 for most workloads and Fable 5.1 for demanding reasoning, long-horizon agentic work, or tasks where Opus 5.5 at higher effort still falls short.
Verdict based on published prices, limits and benchmarks, not on our own tests.
Choose Claude Opus 5.5 if
- You want Anthropic's recommended default, at the lower price
- You want the higher scores on Artificial Analysis (57.6 against 53.4 on the Intelligence Index at max effort)
- You need zero data retention, which Fable 5.1 does not offer by default
Choose Claude Fable 5.1 if
- Opus 5.5 at high effort has already fallen short on your task
- You run multi-hour or multi-day autonomous projects, which Anthropic positions Fable 5.1 for
- You want Anthropic's top tier inside the Claude apps and have a Max, Team or Enterprise plan
Price
Input costs 2.5 times as much on Claude Fable 5.1 as on Claude Opus 5.5. Output costs 2.5 times as much on Claude Fable 5.1 as on Claude Opus 5.5.
| Per million tokens | Claude Opus 5.5 | Claude Fable 5.1 |
|---|---|---|
| Input | $4 source | $10 source |
| Cached input | $0.20 source | $0.25 source |
| Output | $20 source | $50 source |
Claude Opus 5.5: Cache writes cost $5 per million tokens (5-minute cache) or $8 (1-hour cache). The Batch API costs half. There is no long-context surcharge. Fast mode costs $8 in and $40 out.
Claude Fable 5.1: Cache writes cost $12.50 per million tokens (5-minute cache) or $20 (1-hour cache). The Batch API costs half. There is no long-context surcharge and no fast mode.
Worked example: what a month costs
We priced three monthly workloads at the standard rates. The provider does not publish these figures.
| Workload | Claude Opus 5.5 | Claude Fable 5.1 |
|---|---|---|
| Support chatbot 100,000 replies, each 3,000 input and 400 output tokens, no caching (300M in, 40M out) | $2,000 | $5,000 |
| Document Q&A 5,000 questions over the same 60,000-token document set (90% cache hits), 800 output tokens each (300M in, 4M out) | $254 | $568 |
| Coding agent 200 tasks, each 1.5 million input tokens (90% cache hits) and 50,000 output tokens (300M in, 10M out) | $374 | $868 |
Price your own workload
| Model | Cost a month |
|---|---|
| Claude Opus 5.5 | $300 |
| Claude Fable 5.1 | $750 |
Standard API prices, no batch or priority discounts. Cached input is billed at the cache-read price; cache-write charges are not included. Reasoning models bill their thinking as output tokens.
Limits and release dates
| Claude Opus 5.5 | Claude Fable 5.1 | |
|---|---|---|
| Released | September 22, 2026 source | September 1, 2026 source |
| Context window | 1,000,000 tokens source | 1,000,000 tokens source |
| Maximum output | 128,000 tokens source | 128,000 tokens source |
| Knowledge cutoff | June 2026 source | June 2026 source |
| Input and output | Text and images in; text out source | Text and images in; text out source |
| API model name | claude-opus-5-5 | claude-fable-5-1 |
Benchmarks
Scores as published by the provider or measured by Artificial Analysis; higher is better. A dash means no score was published.
| Benchmark | Claude Opus 5.5 | Claude Fable 5.1 |
|---|---|---|
| Artificial Analysis Intelligence Index max effort | 57.6 source | 53.4 source |
| Intelligence Index at everyday effort | 51.2 (medium effort, the API default) source | 51.2 (high effort, the API default) source |
| Coding Agent Index Claude Code harness, max effort | 66.0 source | 62.2 source |
| Terminal-Bench 4.0 max effort | 59.6% source | 52.0% source |
| Humanity's Last Exam max effort | 61.4% source | 59.1% source |
| GDPval-AA v2.1 (Elo) max effort | 1866 source | 1758 source |
| SciCode max effort | 66.9% source | 63.1% source |
| Terminal-Bench-Science 0.1 max effort | 59.0% source | 43.3% source |
| GPQA Diamond | – | 93.7% (max effort) source |
| Output speed | 79.2 tokens/s (medium effort, Anthropic API) source | 57.8 tokens/s (high effort, Anthropic API) source |
Benchmark and speed data from Artificial Analysis where linked.
Read more
- Claude Opus 5.5: price, context window and benchmarks
- Claude Fable 5.1: price, context window and benchmarks
- Claude Opus 5.5 vs GPT-6 Astra
- GPT-6.1 Sol vs Claude Opus 5.5
- AI model API price table
Sources
- Anthropic: Introducing Claude Opus 5.5 (checked 2026-10-06)
- Claude docs: Claude Opus 5.5 (checked 2026-10-06)
- Claude docs: What's new in Claude Opus 5.5 (checked 2026-10-06)
- Claude docs: Pricing (checked 2026-10-06)
- Claude plans and pricing (checked 2026-10-06)
- Claude docs: API and data retention (checked 2026-10-06)
- Artificial Analysis: Claude Opus 5.5 (max) (checked 2026-10-06)
- Artificial Analysis: Claude Opus 5.5 (medium) (checked 2026-10-06)
- Artificial Analysis: Coding agents (checked 2026-10-06)
- OpenRouter: Claude Opus 5.5 (checked 2026-10-06)
- Anthropic: Introducing Claude Fable 5.1 and Claude Mythos 5.1 (checked 2026-10-06)
- Claude docs: Claude Fable 5.1 (checked 2026-10-06)
- Artificial Analysis: Claude Fable 5.1 (max) (checked 2026-10-06)
- Artificial Analysis: Claude Fable 5.1 (high) (checked 2026-10-06)
- OpenRouter: Claude Fable 5.1 (checked 2026-10-06)