Claude Mythos 5.1 vs Claude Sonnet 4.5
At a Glance
| Compare | Claude Mythos 5.1Anthropic | Claude Sonnet 4.5Anthropic |
|---|---|---|
| Intelligence, Cost, and Efficiency | ||
| IntelligenceHigher is better · MM Intelligence v2.5 | UnrankedNot in the 46-model eligible cohort | #36 of 4627.7 score · 2/3 sources · provisional · missing LiveBench · full-core range 18.5–51.8 |
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $10.00Anthropic ↗ · Sep 2, 2026 | $3.00Anthropic ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $50.00Anthropic ↗ · Sep 2, 2026 | $15.00Anthropic ↗ · 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 Sonnet 4.5 |
|---|---|---|
| Developer | Anthropic | Anthropic |
| Family | Claude 5 1 | Claude 4 |
| Model | Claude Mythos 5.1 | Claude Sonnet 4.5 |
| Version | Claude Mythos 5.1 | Claude Sonnet 4.5 |
| Lifecycle | active | active |
| Released | 2026-09-01 | 2025-09-29 |
| Knowledge cutoff | 2026-06-01 | 2025-01-01 |
| 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 Sonnet 4.5 Capabilities
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Primary Evidence
Sources and Freshness
Questions
Claude Mythos 5.1 vs Claude Sonnet 4.5 FAQs
Is Claude Mythos 5.1 or Claude Sonnet 4.5 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both Claude Mythos 5.1 and Claude Sonnet 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 Sonnet 4.5?+
Claude Mythos 5.1 is $10.00 and Claude Sonnet 4.5 is $3.00 per million tokens, so Claude Sonnet 4.5 is cheaper on this metric. Claude Mythos 5.1 is $50.00 and Claude Sonnet 4.5 is $15.00 per million tokens, so Claude Sonnet 4.5 is cheaper on this metric.
Which has a larger context window, Claude Mythos 5.1 or Claude Sonnet 4.5?+
Claude Mythos 5.1 has the larger sourced context window. Claude Mythos 5.1 supports 1,000K and Claude Sonnet 4.5 supports 200K.
Which performs better in benchmarks, Claude Mythos 5.1 or Claude Sonnet 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 Sonnet 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 Sonnet 4.5 is not marked open weight.
Can Claude Mythos 5.1 and Claude Sonnet 4.5 understand images?+
Claude Mythos 5.1 is documented with image input; Claude Sonnet 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 Sonnet 4.5?+
Claude Mythos 5.1 has the larger sourced maximum output: Claude Mythos 5.1 supports 128K and Claude Sonnet 4.5 supports 64K output tokens.
Do Claude Mythos 5.1 and Claude Sonnet 4.5 support reasoning and tool use?+
Claude Mythos 5.1: reasoning, tool calling, and image input. Claude Sonnet 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 Sonnet 4.5?+
Claude Mythos 5.1 has 1 sourced provider route; Claude Sonnet 4.5 has 1, a tie.
Which offers better value, Claude Mythos 5.1 or Claude Sonnet 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.