Claude Mythos 5.1 vs Claude Opus 4.5
At a Glance
| Compare | Claude Mythos 5.1Anthropic | Claude Opus 4.5Anthropic |
|---|---|---|
| Intelligence, Cost, and Efficiency | ||
| IntelligenceHigher is better · MM Intelligence v2.5 | UnrankedNot in the 46-model eligible cohort | #27 of 4655.4 score · 2/3 sources · provisional · missing ARC-AGI-2 · full-core range 36.9–70.3 |
| CostLower is better · Published-token output estimate | UnrankedNot in the 44-model eligible cohort | #40 of 44$0.380 per LiveBench case |
| EfficiencyHigher is better · MM Efficiency v1.5 | UnrankedNot in the 38-model eligible cohort | #36 of 3838.0 score · 2/3 sources · provisional · missing ARC-AGI-2 · full-core range 28.8–45.4 |
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $10.00Anthropic ↗ · Sep 2, 2026 | $5.00Anthropic ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $50.00Anthropic ↗ · Sep 2, 2026 | $25.00Anthropic ↗ · Sep 3, 2026 |
| Context windowMaximum documented tokens | 1,000K | 200K |
| Model facts checked | Sep 2, 2026View model evidence → | Sep 3, 2026View model evidence → |
Token prices are the lowest available sourced USD rates; input and output may use different providers. Cost ranking estimates output spend on LiveBench, not a full request bill. Ranking methodology →
Available Benchmarks
Side-by-Side Facts
| Field | Claude Mythos 5.1 | Claude Opus 4.5 |
|---|---|---|
| Developer | Anthropic | Anthropic |
| Family | Claude 5 1 | Claude 4 |
| Model | Claude Mythos 5.1 | Claude Opus 4.5 |
| Version | Claude Mythos 5.1 | Claude Opus 4.5 |
| Lifecycle | active | active |
| Released | 2026-09-01 | 2025-11-24 |
| Knowledge cutoff | 2026-06-01 | 2025-05-01 |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
| Context window | 1,000K | 200K |
| Total parameters | Unknown | Unknown |
| Active parameters | Unknown | Unknown |
| License | Unknown | Unknown |
| Open weights | No | No |
| API available | Yes | Yes |
| Self-hostable | No | No |
| Provider access | Anthropic (Project Glasswing) | Anthropic (Standard) |
| Capabilities | chat, generation, reasoning, tools | chat, generation, reasoning, structured_outputs, tools |
Claude Mythos 5.1 Capabilities
Claude Opus 4.5 Capabilities
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Primary Evidence
Sources and Freshness
Questions
Claude Mythos 5.1 vs Claude Opus 4.5 FAQs
Is Claude Mythos 5.1 or Claude Opus 4.5 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both Claude Mythos 5.1 and Claude Opus 4.5, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, Claude Mythos 5.1 or Claude Opus 4.5?+
Claude Mythos 5.1 is $10.00 and Claude Opus 4.5 is $5.00 per million tokens, so Claude Opus 4.5 is cheaper on this metric. Claude Mythos 5.1 is $50.00 and Claude Opus 4.5 is $25.00 per million tokens, so Claude Opus 4.5 is cheaper on this metric.
Which has a larger context window, Claude Mythos 5.1 or Claude Opus 4.5?+
Claude Mythos 5.1 has the larger sourced context window. Claude Mythos 5.1 supports 1,000K and Claude Opus 4.5 supports 200K.
Which performs better in benchmarks, Claude Mythos 5.1 or Claude Opus 4.5?+
There is no overall benchmark winner: At least two independently verified, protocol-matched benchmarks are required for an overall winner.
Can Claude Mythos 5.1 or Claude Opus 4.5 be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. Claude Mythos 5.1 is not marked open weight; Claude Opus 4.5 is not marked open weight.
Can Claude Mythos 5.1 and Claude Opus 4.5 understand images?+
Claude Mythos 5.1 is documented with image input; Claude Opus 4.5 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, Claude Mythos 5.1 or Claude Opus 4.5?+
Claude Mythos 5.1 has the larger sourced maximum output: Claude Mythos 5.1 supports 128K and Claude Opus 4.5 supports 64K output tokens.
Do Claude Mythos 5.1 and Claude Opus 4.5 support reasoning and tool use?+
Claude Mythos 5.1: reasoning, tool calling, and image input. Claude Opus 4.5: reasoning, tool calling, and image input. Feature support does not establish relative quality.
Which is available from more inference providers, Claude Mythos 5.1 or Claude Opus 4.5?+
Claude Mythos 5.1 has 1 sourced provider route; Claude Opus 4.5 has 1, a tie.
Which offers better value, Claude Mythos 5.1 or Claude Opus 4.5?+
There is no universal value winner. Compare the input and output prices above with the matched benchmark result for your workload: cheaper tokens can be offset by different quality, token usage, latency, or provider availability.