LLM Reference

Claude Mythos Preview vs Gemini 3 Flash Preview

Claude Mythos Preview (2026) and Gemini 3 Flash Preview (2025) are frontier reasoning models from Anthropic and Google DeepMind. Claude Mythos Preview ships a 1m-token context window, while Gemini 3 Flash Preview ships a 1m-token context window. On pricing, Gemini 3 Flash Preview costs $0.50/1M 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.

Gemini 3 Flash Preview is ~4900% cheaper at $0.50/1M; pay for Claude Mythos Preview only for coding workflow support.

Decision scorecard

Local evidence first
SignalClaude Mythos PreviewGemini 3 Flash Preview
Best forreasoning-heavy apps, multimodal apps, and tool-calling agentsmultimodal apps, tool-calling agents, and long-context analysis
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m1m
Cheapest output$125/1M tokens$3/1M tokens
Provider routes2 tracked3 tracked
Shared benchmarks0 shared0 shared

Decision tradeoffs

Choose Claude Mythos Preview when...
  • Claude Mythos Preview uniquely exposes Reasoning in local model data.
  • Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
Choose Gemini 3 Flash Preview when...
  • Gemini 3 Flash Preview has the lower cheapest tracked output price at $3/1M tokens.
  • Gemini 3 Flash Preview has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags Gemini 3 Flash Preview 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 Gemini 3 Flash Preview

Claude Mythos Preview

$51,250

Cheapest tracked route/tier: Anthropic

Gemini 3 Flash Preview

$1,150

Cheapest tracked route/tier: GCP Vertex AI

Estimated monthly gap: $50,100. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Mythos Preview -> Gemini 3 Flash Preview
  • No overlapping tracked provider route is sourced for Claude Mythos Preview and Gemini 3 Flash Preview; plan for SDK, billing, or endpoint changes.
  • Gemini 3 Flash Preview is $122/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Check replacement coverage for Reasoning before moving production traffic.
Gemini 3 Flash Preview -> Claude Mythos Preview
  • No overlapping tracked provider route is sourced for Gemini 3 Flash Preview and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
  • Claude Mythos Preview is $122/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Claude Mythos Preview adds Reasoning in local capability data.

Specs

Specification
Released2026-05-012025-12-17
Context window1m1m
Parameters——
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2025-122025-01

Pricing and availability

Pricing attributeClaude Mythos PreviewGemini 3 Flash Preview
Input price$25/1M tokens$0.50/1M tokens
Output price$125/1M tokens$3/1M tokens
Providers
AnthropicMicrosoft Foundry
GCP Vertex AIOpenRouterGoogle AI Studio

Capabilities

CapabilityClaude Mythos PreviewGemini 3 Flash Preview
VisionYesYes
MultimodalYesYes
ReasoningYesNo
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

No shared benchmark scores are currently available for this pair.

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