LLM Reference

Claude Mythos Preview vs Claude Opus 4.6

Claude Mythos Preview (2026) and Claude Opus 4.6 (2026) are frontier-tier reasoning models from Anthropic. Claude Mythos Preview ships a 1m-token context window, while Claude Opus 4.6 ships a 1m-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 13.1 pts. On pricing, Claude Opus 4.6 costs $5/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Claude Opus 4.6 is ~400% cheaper at $5/1M; pay for Claude Mythos Preview only for coding workflow support.

Decision scorecard

Local evidence first
SignalClaude Mythos PreviewClaude Opus 4.6
Best forreasoning-heavy apps, multimodal apps, and tool-calling agentsreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m1m
Cheapest output$125/1M tokens$25/1M tokens
Provider routes2 tracked6 tracked
Shared benchmarksSWE-bench Verified leader3 shared

Decision tradeoffs

Choose Claude Mythos Preview when...
  • Claude Mythos Preview holds a shared-benchmark lead on SWE-bench Verified, ahead by 13.1 points.
  • Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
Choose Claude Opus 4.6 when...
  • Claude Opus 4.6 has the lower cheapest tracked output price at $25/1M tokens.
  • Claude Opus 4.6 has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags Claude Opus 4.6 for Coding, RAG, and Agents.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate Claude Opus 4.6

Claude Mythos Preview

$51,250

Cheapest tracked route/tier: Anthropic

Claude Opus 4.6

$10,250

Cheapest tracked route/tier: Anthropic

Estimated monthly gap: $41,000. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Mythos Preview -> Claude Opus 4.6
  • Provider overlap exists on Anthropic and Microsoft Foundry; start route-level A/B tests there.
  • Claude Opus 4.6 is $100/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
Claude Opus 4.6 -> Claude Mythos Preview
  • Provider overlap exists on Anthropic and Microsoft Foundry; start route-level A/B tests there.
  • Claude Mythos Preview is $100/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.

Specs

Specification
Released2026-05-012026-02-05
Context window1m1m
Parameters——
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2025-122025-12

Pricing and availability

Pricing attributeClaude Mythos PreviewClaude Opus 4.6
Input price$25/1M tokens$5/1M tokens
Output price$125/1M tokens$25/1M tokens
Providers
AnthropicMicrosoft Foundry
AnthropicAWS BedrockGCP Vertex AIMicrosoft FoundryOpenRouterVercel AI Gateway

Capabilities

CapabilityClaude Mythos PreviewClaude Opus 4.6
VisionYesYes
MultimodalYesYes
ReasoningYesYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkClaude Mythos PreviewClaude Opus 4.6
SWE-bench Verified93.980.8
Google-Proof Q&A94.691.3
τ-bench89.284.8

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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.