Claude Mythos 5.1 vs Claude Fable 5.1
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by Anthropic
|
by Anthropic
|
|---|---|---|
| Overview | ||
| Status | Current flagship | Current flagship |
| Released | Sep 1, 2026 | Sep 1, 2026 |
| Pricing per million tokens | ||
| Input | $10.00/Mtok | $10.00/Mtok |
| Output | $50.00/Mtok | $50.00/Mtok |
| Blended avg | $20.00/Mtok | $20.00/Mtok |
| Cached input | $0.250/Mtok | $0.250/Mtok |
| Price basis | Cache hits and refreshes on Claude Mythos 5.1 (and Claude Fable 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. | 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. |
| Specifications | ||
| Context window | 1M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimage
|
| Benchmarks source: Vellum LLM Leaderboard | ||
| Avg benchmark score | 55.9 | 54.2 |
| Perf / dollar | 2.8 | 2.7 |
| Terminal-Bench 2.1 | 60.9 | 55.8 |
| OSWorld-Verified | 41.7 | 41.7 |
| Humanity's Last Exam | 65 | 65 |
| AutoBench | 31.4 | 31.4 |
| Independent composite scores each on its own scale — not part of the average above | ||
| AA Intelligence Index | — | 65.7 |
| AA Agentic Index | — | 61.3 |
| AA-Omniscience Index (−100–100) | — | 43.5 |
| GDPval-AA v2 | — | 1853 ELO |
| Providers | ||
| Available from |
Anthropic — $10.00/$50.00/Mtok
|
Anthropic — $10.00/$50.00/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Claude Mythos 5.1 | Claude Fable 5.1 | Savings |
|---|---|---|---|
| 1M tokens | $20 | $20 | $0 (0%) |
| 10M tokens | $200 | $200 | $0 (0%) |
| 100M tokens | $2000 | $2000 | $0 (0%) |
| 1000M tokens | $20000 | $20000 | $0 (0%) |
When to pick which
distilled from the pricing and spec data above- raw capability matters more than price: 55.9 vs 54.2 average benchmark score
- this pairing gives Claude Fable 5.1 no edge on price, context, cache discount, or measured performance — pick it only for qualitative fit (ecosystem, compliance, model behavior on your prompts)
The cheaper option here — Claude Mythos 5.1 costs $20.00/Mtok blended on Anthropic.
Summary
Claude Mythos 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 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.
On benchmarks, Claude Mythos 5.1 scores higher (55.9 vs 54.2) on average. In terms of value, Claude Mythos 5.1 has better performance per dollar (2.8 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.