New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
100
Coding
98
Writing
100
Research
90
Images
20
Value
99
Long Context
Use this when
Frontier agentic coding, long-horizon autonomous work, and agentic scientific research
Skip this if
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
Pricing
$10.00/1M in
$50.00/1M out
↑100%since Sep 2026
Context
1M tokens
Speed
Deliberate
Claude Fable 5.1specs & pricing
Verified Sep 4, 2026 against the AI Gateway catalog
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
52.6% Terminal-Bench-Science 0.1 — 2.1x Fable 5 (24.7%), well clear of Opus 5 (29.0%) and GPT-5.6 Sol (22.4%)
55.8% Terminal-Bench 4.0 agentic coding, ahead of Opus 5 (52.3%) and Fable 5 (42.0%)
Cache reads cut 75% to $0.25/1M — ~25% cheaper for typical use, ~45% for heavily agentic work
Independent Vals AI evaluation ranks it #1 of 51 on the Vals Index, #1 on LiveCodeBench (90.5%) and MMLU Pro (92.4%)
1M-token context and 128K max output at standard rates, with adaptive thinking always enabled
Weaknesses
Base rates are still $10/$50 per 1M — double Claude Opus 5 for anything that is not cache-heavy
Anthropic published no SWE-bench Verified or SWE-bench Pro figure for 5.1 at launch
On Claude Pro it only runs on pay-as-you-go credits; Max includes it up to 50% of weekly limits
Deliberate, high-latency profile — the wrong choice for interactive, latency-bound apps
Real-world use cases
What people actually use Claude Fable 5.1 for.
Agentic scientific research — 52.6% on Terminal-Bench-Science 0.1, more than double Fable 5's 24.7%
Long-running autonomous coding agents that plan, run, and debug across a whole repository
Cache-heavy agent loops where the 75% cache-read cut ($1.00 → $0.25 per 1M) is the real saving
How Claude Fable 5.1 compares
The nearest models people weigh against it, and what actually separates them.
vs Claude Fable 5 — Against Claude Fable 5 (Anthropic), Claude Fable 5.1 lands within a few percent on price. Which one wins depends on whether context depth or latency is your constraint.
vs Claude Opus 4.7 — Against Claude Opus 4.7 (Anthropic), Claude Fable 5.1 costs about 50% more per token. Claude Opus 4.7 is the one to check first if the price difference matters more than the ceiling.
vs Claude Opus 4.8 — Against Claude Opus 4.8 (Anthropic), Claude Fable 5.1 costs about 50% more per token. Claude Opus 4.8 is the one to check first if the price difference matters more than the ceiling.
Price History
Claude Fable 5.1 pricing over time
↑100% since Sep 2
7 data points · tracked daily since Sep 2, 2026
Ready to try it?
Start using Claude Fable 5.1
Frontier agentic coding, long-horizon autonomous work, and agentic scientific research. Start free — no card required.
Anthropic's new Mythos-class flagship and the most capable coding model anyone can use — 80.3% SWE-Bench Pro, an 11-point jump over Opus 4.8. 1M context, 128K output, native parallel subagents. Released June 9, 2026.
Verdict
New global #1 — 80.3% SWE-Bench Pro, the most capable model generally available.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched June 9, 2026 as the public, Mythos-class release. Available on the Claude API, Microsoft Foundry, and Google Vertex AI. Free for all users until June 22, 2026. Same underlying model as Claude Mythos 5, with safeguards that block specific high-risk cyber responses.
Coding leaderSWE-Bench Pro #1Mythos-classParallel subagentsAgenticLong contextPremiumNew
Best for
The hardest coding tasks, autonomous multi-step agents, and frontier-grade reasoning
Anthropic's newest Opus flagship — 69.2% SWE-Bench Pro, 88.6% SWE-Bench Verified, 1890 Arena Elo (121 pts ahead of GPT-5.5), and native parallel subagents. Same $5/$25 price as Opus 4.7.
Verdict
Best value premium coder — frontier-grade at half of Fable 5's price.
Quality score
97%
Pricing
$5.00/1M in
$25.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched May 27, 2026. Available on Claude API, AWS Bedrock, Google Vertex AI, Microsoft Foundry, and GitHub Copilot. Fast mode available at $10/$50 per 1M tokens.
Coding leaderSWE-bench Pro #1Parallel subagentsAgenticLong contextPremiumNew
Best for
Hardest coding tasks, parallel agentic workflows, and high-fidelity vision
Claude Fable 5.1 and Mythos 5.1 released — better on every published benchmark, and cheaper to run
Anthropic shipped Claude Fable 5.1 and Claude Mythos 5.1 on September 1, 2026 — the first update to the Mythos-class line since Fable 5 launched on June 9. Base pricing did not move ($10 in / $50 out per 1M tokens), but cache reads were cut 75%, from $1.00 to $0.25 per 1M. Anthropic puts the net effect at roughly 25% cheaper on typical workloads and up to 45% on heavily agentic ones — an upgrade that costs less than the model it replaces. The headline result is Terminal-Bench-Science 0.1, where Fable 5.1 scores 52.6% against Fable 5's 24.7%, Opus 5's 29.0% and GPT-5.6 Sol's 22.4%. It also leads Terminal-Bench 4.0 agentic coding (55.8% vs 52.3% for Opus 5), CursorBench 3.2.0 (73.4%) and AutomationBench (31.4%, nearly double Fable 5's 17.1%). Anthropic published no SWE-bench Verified or Pro figure at launch, so our SWE-bench leaderboard is unchanged; independent evaluator Vals AI ranks Fable 5.1 first of 51 models on its Vals Index, first on LiveCodeBench (90.5%) and first on MMLU Pro (92.4%). Mythos 5.1 is the same model with safeguards lifted, scores 60.9% on Terminal-Bench 4.0, and stays restricted to vetted US cybersecurity and life-sciences organisations. API ID claude-fable-5-1, generally available on the Claude API, Amazon Bedrock, Google Cloud and Microsoft Foundry. Every figure verified against Anthropic's launch numbers and two independent write-ups on September 1, 2026.
Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens on the API, with cached input at $0.25 per million. A month of 10M input and 2M output tokens runs about $200.00 at list price, before any batch or caching discounts.
What is the context window of Claude Fable 5.1?
Claude Fable 5.1 has a 1M tokens context window, with up to 128k tokens of output per response. That is the total of prompt plus response the model can hold in one request.
What is the knowledge cutoff of Claude Fable 5.1?
Claude Fable 5.1's training data runs through June 1, 2026, and the model was released on August 31, 2026. For anything after that date it needs web search or documents in the prompt.
What is Claude Fable 5.1 best for?
Claude Fable 5.1 is best for frontier agentic coding, long-horizon autonomous work, and agentic scientific research. It is a strong fit when that workflow matters more than the tradeoffs around premium pricing and deliberate speed.
When should I avoid Claude Fable 5.1?
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
What is a cheaper alternative to Claude Fable 5.1?
Claude Opus 4.8 (Anthropic) at $5.00/1M/1M input against Claude Fable 5.1's $10.00/1M/1M — roughly 50% less per token all in. Best value premium coder — frontier-grade at half of Fable 5's price. Compare it first if Claude Fable 5.1's pricing is the thing stopping you.
What is a faster alternative to Claude Fable 5.1?
Claude Fable 5 — deliberate against Claude Fable 5.1's deliberate, with 1M tokens of context. Worth the swap when response time is what your users notice rather than the last few points of reasoning depth.
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