Claude Mythos 5.1 vs o3-pro
At a Glance
| Compare | Claude Mythos 5.1Anthropic |  o3-proOpenAI |
|---|---|---|
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $10.00Anthropic ↗ · Sep 2, 2026 | $20.00Openai ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $50.00Anthropic ↗ · Sep 2, 2026 | $80.00Openai ↗ · 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 | o3-pro |
|---|---|---|
| Developer | Anthropic | OpenAI |
| Family | Claude 5 1 | O3 |
| Model | Claude Mythos 5.1 | o3-pro |
| Version | Claude Mythos 5.1 | o3-pro |
| Lifecycle | active | active |
| Released | 2026-09-01 | 2025-06-10 |
| Knowledge cutoff | 2026-06-01 | 2024-06-01 |
| 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) | Openai (Standard), Openrouter (Standard) |
| Capabilities | chat, generation, reasoning, tools | chat, generation, reasoning, structured_outputs, tools |
Claude Mythos 5.1 Capabilities
o3-pro Capabilities
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Claude Mythos 5.1Anthropic | vs | Seed 2.1 ProByteDance Seed | cross-developer peersimage, text |
Claude Mythos 5.1Anthropic | vs |  Mistral Large 3Mistral AI | cross-developer peersimage, text |
Primary Evidence
Sources and Freshness
Questions
Claude Mythos 5.1 vs o3-pro FAQs
Is Claude Mythos 5.1 or o3-pro better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both Claude Mythos 5.1 and o3-pro, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, Claude Mythos 5.1 or o3-pro?+
Claude Mythos 5.1 is $10.00 and o3-pro is $20.00 per million tokens, so Claude Mythos 5.1 is cheaper on this metric. Claude Mythos 5.1 is $50.00 and o3-pro is $80.00 per million tokens, so Claude Mythos 5.1 is cheaper on this metric.
Which has a larger context window, Claude Mythos 5.1 or o3-pro?+
Claude Mythos 5.1 has the larger sourced context window. Claude Mythos 5.1 supports 1,000K and o3-pro supports 200K.
Which performs better in benchmarks, Claude Mythos 5.1 or o3-pro?+
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 o3-pro be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. Claude Mythos 5.1 is not marked open weight; o3-pro is not marked open weight.
Can Claude Mythos 5.1 and o3-pro understand images?+
Claude Mythos 5.1 is documented with image input; o3-pro is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, Claude Mythos 5.1 or o3-pro?+
Claude Mythos 5.1 has the larger sourced maximum output: Claude Mythos 5.1 supports 128K and o3-pro supports 100K output tokens.
Do Claude Mythos 5.1 and o3-pro support reasoning and tool use?+
Claude Mythos 5.1: reasoning, tool calling, and image input. o3-pro: 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 o3-pro?+
Claude Mythos 5.1 has 1 sourced provider route; o3-pro has 2, so o3-pro has broader tracked availability.
Which offers better value, Claude Mythos 5.1 or o3-pro?+
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.