For most workflows, Claude Fable 5.1 is the stronger default — new frontier leader — better than fable 5 on every published benchmark, and cheaper to run.
The shortest way to see the safest default, the lower-cost option, and the specialist pick before you read deeper.
Claude Fable 5.1 is the safest overall answer here when you want the strongest default instead of the lowest list price.
Grok 4.5 is the lower-cost option to start with when you still need useful output at scale.
Claude Mythos 5 is the better pick when response speed matters more than maximum reasoning depth.
Claude Fable 5.1 leads on coding with a score of 100 vs 100 for Claude Mythos 5.
Both models are similarly priced — the decision comes down to capability, not cost.
Claude Fable 5.1 is the stronger default for coding tasks.
Claude Fable 5.1 is the safer default: it is built for frontier agentic coding, long-horizon autonomous work, and agentic scientific research, which covers most of what people bring to this comparison.
Choose Claude Mythos 5 when your work is mostly frontier cybersecurity research and autonomous vulnerability discovery — that is the workload it was tuned for.
Both models serve different primary workflows — Claude Fable 5.1 for frontier agentic coding and long-horizon autonomous work, Claude Mythos 5 for frontier cybersecurity research and autonomous vulnerability discovery — so running each where it has a clear edge often beats forcing one to do both.
Switch the scoring lens to see whether the top answer changes when you care more about cost, speed, or long-document work.
Anthropic / Premium / Sep 1, 2026
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
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.
The fastest way to see where the recommendation shifts when your priority changes.
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Superseded by Mythos 5.1 — same model as Fable 5, safeguards lifted, partner-only.
Every figure below is the provider's list price or a published capability score — the same numbers the recommendation on this page is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| Claude Fable 5.1Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 98 | 100 |
| Claude Mythos 5Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 97 | 99 |
Capability scores are out of 100 and reflect our own weighting of published benchmarks and production signals — see how we evaluate models. “Est. month” assumes 10M input and 2M output tokens at list price, with no batch or caching discounts applied, so treat it as a ceiling.
What each one is genuinely good at, where it falls down, and the situations we would steer you away from it — not just the headline score.
Anthropic's September 1, 2026 frontier release and the new capability ceiling for coding, agents, and scientific work. Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
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.
The new frontier leader, and the rare upgrade that costs less than the model it replaces. Base $10/$50 pricing did not move, but a 75% cut to cache reads makes typical workloads ~25% cheaper than Fable 5 and heavily agentic ones ~45% cheaper — while more than doubling Fable 5 on agentic science and beating Opus 5 on agentic coding. If you were already on Fable 5, switching is a straight win. If you were on Opus 5 for the price, it still costs 2x on uncached tokens.
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.
Anthropic's most powerful frontier model — the same underlying model as Fable 5 with safeguards lifted in some areas, restricted to vetted enterprise and research partners. The capability ceiling of mid-2026.
You don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price.
The most capable model Anthropic has ever shipped — but access is gated to vetted partners because its safeguards are lifted in high-risk areas. For everyone else, Fable 5 is the same model at the same price with standard safety controls. Choose Mythos 5 only if you have partner access and need its security ceiling.
Launched June 9, 2026 alongside Fable 5, following the April Project Glasswing private preview on Google Cloud. Restricted to vetted enterprise and research partners due to advanced cybersecurity capabilities. Same underlying model and benchmarks as Claude Fable 5. Superseded by Claude Mythos 5.1 on September 1, 2026.
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Claude Fable 5.1 wins on more of the categories we score — coding, research, long context — so it is the better default of the two. Claude Mythos 5 is the better pick when your work is mostly frontier cybersecurity research and autonomous vulnerability discovery. Neither is universally "better": Claude Fable 5.1 is aimed at frontier agentic coding and long-horizon autonomous work, Claude Mythos 5 at frontier cybersecurity research and autonomous vulnerability discovery.
Both models are similarly priced at $10/1M input tokens. The decision should come down to capability, not cost.
Both Claude Fable 5.1 and Claude Mythos 5 have the same 1M context window.
Claude Fable 5.1 and Claude Mythos 5 are similarly matched on coding. Claude Fable 5.1 is the overall coding leader in this directory at 100/100.
Both Claude Fable 5.1 and Claude Mythos 5 have similar speed profiles — rated deliberate. Neither will be the bottleneck if latency is your deciding factor.
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. Avoid it 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. That is the main case for looking at Claude Mythos 5 instead.
Not generally available — limited to vetted partners after Project Glasswing's private preview. Most teams should use Fable 5, which is the same model with standard safeguards. Premium $10/$50 pricing and a deliberate, high-latency profile. Avoid it if you don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price. Against Claude Fable 5.1 specifically, the two are close enough on capability that price and speed decide it.
Take a moderate workload of 10M input and 2M output tokens a month. Claude Fable 5.1 runs $200.00 (at $10/1M in and $50/1M out); Claude Mythos 5 runs $200.00 (at $10/1M in and $50/1M out). The gap is small enough that price should not decide this one. Output tokens dominate the bill on both, so prompt length matters far less than response length.
Yes, and for most teams that beats picking one. A common split is Claude Fable 5.1 for frontier agentic coding and long-horizon autonomous work, with Claude Mythos 5 handling frontier cybersecurity research and autonomous vulnerability discovery. Since Claude Fable 5.1 is both the stronger and the cheaper option here, a split mainly makes sense if Claude Mythos 5 covers a capability you specifically need.