Claude Fable 5.1 vs Claude Sonnet 5
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by Anthropic
|
by Anthropic
|
|---|---|---|
| Overview | ||
| Status | Current flagship | Current mid tier |
| Released | Sep 1, 2026 | Jun 30, 2026 |
| Pricing per million tokens | ||
| Input | $10.00/Mtok | $2.00/Mtok |
| Output | $50.00/Mtok | $10.00/Mtok |
| Blended avg | $20.00/Mtok | $4.00/Mtok |
| Cached input | $0.250/Mtok | $0.200/Mtok |
| Price basis | Cache hits and refreshes on Claude Fable 5.1 (and Claude Mythos 5.1) are priced at 0.025x the base input price — $0.25 per 1M tokens — where every other Claude model uses the standard 0.1x multiplier. Base $10/$50 per 1M tokens; Batch API $5/$25. Verified 2026-09-01 against platform.claude.com/docs/en/about-claude/pricing. | Standard pricing, per 1M tokens — not a promotional rate. $2/$10 was announced at launch as introductory pricing through Aug 31 2026, but Anthropic's pricing page now states that it "is now the standard price" and that "the previously scheduled increase to $3/$15 per million input/output tokens on September 1, 2026 will not occur". There is therefore no reversion date to watch. Verified 2026-08-13 against platform.claude.com/docs/en/about-claude/pricing. |
| Specifications | ||
| Context window | 1M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimage
|
| Benchmarks source: Vellum LLM Leaderboard | ||
| Avg benchmark score | 54.2 | 81.5 |
| Perf / dollar | 2.7 | 20.4 |
| Terminal-Bench 2.1 | 55.8 | 80.4 |
| OSWorld-Verified | 41.7 | 81.2 |
| Humanity's Last Exam | 65 | 57.4 |
| AutoBench | 31.4 | 13.5 |
| GPQA Diamond | — | 96.2 |
| SWE-Bench Verified | — | 85.2 |
| BrowseComp | — | 84.7 |
| HumanEval | — | 85.2 |
| Independent composite scores each on its own scale — not part of the average above | ||
| AA Intelligence Index | 65.7 | 55.3 |
| AA Agentic Index | 61.3 | 49.7 |
| AA-Omniscience Index (−100–100) | 43.5 | 16.4 |
| GDPval-AA v2 | 1853 ELO | 1598.2 ELO |
| Providers | ||
| Available from |
Anthropic — $10.00/$50.00/Mtok
|
Anthropic — $2.00/$10.00/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Claude Fable 5.1 | Claude Sonnet 5 | Savings |
|---|---|---|---|
| 1M tokens | $20 | $4 | $16 (80%) |
| 10M tokens | $200 | $40 | $160 (80%) |
| 100M tokens | $2000 | $400 | $1600 (80%) |
| 1000M tokens | $20000 | $4000 | $16000 (80%) |
When to pick which
distilled from the pricing and spec data above- your workload re-reads context (agents, RAG, long chats): cached input costs $0.250/Mtok — 98% off its list input price
- cost dominates: $4.00/Mtok blended vs $20.00 — 80% less on the same 50/50 token mix
- raw capability matters more than price: 81.5 vs 54.2 average benchmark score
The cheaper option here — Claude Sonnet 5 costs $4.00/Mtok blended on Anthropic.
Summary
Claude Fable 5.1 by Anthropic costs $10.00/Mtok input and $50.00/Mtok output, with a 1M-token context window. It supports text, image input.
Claude Sonnet 5 by Anthropic costs $2.00/Mtok input and $10.00/Mtok output, with a 1M-token context window. It supports text, image input.
On a blended cost basis, Claude Sonnet 5 is 80% cheaper than Claude Fable 5.1.
On benchmarks, Claude Sonnet 5 scores higher (81.5 vs 54.2) on average. In terms of value, Claude Sonnet 5 has better performance per dollar (20.4 vs 2.7).
Note: Pricing is per million tokens. Actual costs vary with usage patterns, prompt caching, and batch discounts. Always verify against official provider pricing pages.