For most workflows, Claude Mythos 5.1 is the stronger default — fable 5.1 with the safeguards lifted — partner-only, 60.9% terminal-bench 4.0.
The shortest way to see the safest default, the lower-cost option, and the specialist pick before you read deeper.
Claude Mythos 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 Mythos 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 Mythos 5.1 is the stronger default for coding tasks.
Choose Claude Mythos 5.1 for vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling. Its coding and research scores are what carry the recommendation here.
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 Mythos 5.1 for vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling, 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
Fable 5.1 with the safeguards lifted — partner-only, 60.9% Terminal-Bench 4.0.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
You don't hold vetted trusted access, or your work never trips Fable 5.1's safeguards — the two models are otherwise identical.
The fastest way to see where the recommendation shifts when your priority changes.
Fable 5.1 with the safeguards lifted — partner-only, 60.9% Terminal-Bench 4.0.
Superseded by Mythos 5.1 — same model as Fable 5, safeguards lifted, partner-only.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 Mythos 5.1Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 97 | 99 |
| 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.
The unrestricted twin of Claude Fable 5.1 — the same model with safeguards lifted in high-risk areas, released September 1, 2026 to vetted cybersecurity and life-sciences organisations under Anthropic's trusted-access programme. Scores 60.9% on Terminal-Bench 4.0, the highest agentic-coding result Anthropic has published.
You don't hold vetted trusted access, or your work never trips Fable 5.1's safeguards — the two models are otherwise identical.
The highest published agentic-coding score anywhere — 60.9% on Terminal-Bench 4.0 — but you almost certainly cannot get it. Mythos 5.1 is Fable 5.1 with safeguards lifted, gated to vetted cybersecurity and life-sciences organisations. Unless you hold trusted access and hit refusals that block real research, Fable 5.1 is the same model at the same price.
Released September 1, 2026 alongside Claude Fable 5.1, continuing the Mythos-class line that began with Project Glasswing's April 2026 private preview. Access is limited to vetted US cybersecurity and life-sciences professionals. Same underlying model, pricing, context window, and cache-read discount as Fable 5.1; the only published difference is the safeguard level and the resulting Terminal-Bench 4.0 score (60.9% vs 55.8%).
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 Mythos 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 Mythos 5.1 is aimed at vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling, 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 Mythos 5.1 and Claude Mythos 5 have the same 1M context window.
Claude Mythos 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 Mythos 5.1 and Claude Mythos 5 have similar speed profiles — rated deliberate. Neither will be the bottleneck if latency is your deciding factor.
Not generally available — restricted to vetted US organisations under Project Glasswing. No advantage for ordinary work; Fable 5.1 is the same model at the same price for everyone else. Same deliberate, high-latency profile and premium pricing as Fable 5.1. Avoid it if you don't hold vetted trusted access, or your work never trips Fable 5.1's safeguards — the two models are otherwise identical. 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 Mythos 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 Mythos 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 Mythos 5.1 for vetted frontier cybersecurity and life-sciences research at the absolute capability ceiling, with Claude Mythos 5 handling frontier cybersecurity research and autonomous vulnerability discovery. Since Claude Mythos 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.