Claude Mythos 5.1 vs Grok 4.3
Benchmark Performance
Available Benchmarks
Technical Differences
Side-by-Side Facts
| Field | Claude Mythos 5.1 | Grok 4.3 |
|---|---|---|
| Developer | Anthropic | xAI |
| Family | Claude 5 1 | Grok 4 |
| Model | Claude Mythos 5.1 | Grok 4.3 |
| Version | Claude Mythos 5.1 | Grok 4.3 |
| Lifecycle | active | active |
| Released | 2026-09-01 | 2026-06-17 |
| Knowledge cutoff | 2026-06-01 | Unknown |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
| Context window | 1,000,000 | 1,000,000 |
| 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) | Xai (Standard) |
| Capabilities | chat, generation, reasoning, tools | chat, generation, reasoning, structured_outputs, tools |
14 comparable fields · 7 material differences · Pair passes the primary-source comparison gate
Claude Mythos 5.1 Capabilities
Grok 4.3 Capabilities
Internal Comparison Graph
Related Comparisons
| A | Pair | B | Context |
|---|---|---|---|
Claude Fable 5.1Anthropic | vs | Claude Mythos 5.1Anthropic | family variantsimage, text |
Claude Fable 5Anthropic | vs | Claude Mythos 5.1Anthropic | family variantsimage, text |
Claude Mythos 5.1Anthropic | vs | Claude Opus 5Anthropic | family variantsimage, text |
Claude Mythos 5.1Anthropic | vs | Claude Sonnet 5Anthropic | family variantsimage, text |
Claude Mythos 5.1Anthropic | vs |  GPT-5.6 SolOpenAI | cross-developer peersimage, text |
Claude Mythos 5.1Anthropic | vs |  Gemini 3.1 ProGoogle DeepMind | cross-developer peerstext |
Claude Mythos 5.1Anthropic | vs | Grok 4.6xAI | cross-developer peersimage, text |
Claude Mythos 5.1Anthropic | vs |  Kimi-K3Moonshot AI | cross-developer peersimage, text |
Claude Mythos 5.1Anthropic | vs | Gemini 3.8 Flash CyberGoogle DeepMind | cross-developer peerstext |
Grok 4.3xAI | vs | Grok 4.5xAI | family variantsimage, text |
Grok 4.3xAI | vs | family variantsimage, text | |
Grok 4.3xAI | vs | Grok 4.6xAI | family variantsimage, text |
Primary Evidence
Sources and Freshness
Questions
Claude Mythos 5.1 vs Grok 4.3 FAQs
Is Claude Mythos 5.1 or Grok 4.3 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both Claude Mythos 5.1 and Grok 4.3, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, Claude Mythos 5.1 or Grok 4.3?+
Claude Mythos 5.1 is $10.00 and Grok 4.3 is $1.25 per million tokens, so Grok 4.3 is cheaper on this metric. Claude Mythos 5.1 is $50.00 and Grok 4.3 is $2.50 per million tokens, so Grok 4.3 is cheaper on this metric.
Which has a larger context window, Claude Mythos 5.1 or Grok 4.3?+
Neither model has a larger sourced context window in this comparison. Claude Mythos 5.1 is 1,000,000 and Grok 4.3 is 1,000,000.
Which performs better in benchmarks, Claude Mythos 5.1 or Grok 4.3?+
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 Grok 4.3 be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. Claude Mythos 5.1 is not marked open weight; Grok 4.3 is not marked open weight.
Can Claude Mythos 5.1 and Grok 4.3 understand images?+
Claude Mythos 5.1 is documented with image input; Grok 4.3 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, Claude Mythos 5.1 or Grok 4.3?+
Neither has a larger sourced maximum output. Claude Mythos 5.1 is 128,000 and Grok 4.3 is —.
Do Claude Mythos 5.1 and Grok 4.3 support reasoning and tool use?+
Claude Mythos 5.1: reasoning, tool calling, and image input. Grok 4.3: 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 Grok 4.3?+
Claude Mythos 5.1 has 1 sourced provider route; Grok 4.3 has 1, a tie.
Which offers better value, Claude Mythos 5.1 or Grok 4.3?+
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.