Claude Mythos Preview vs Gemini 3.1 Pro Preview

Claude Mythos Preview (2026) and Gemini 3.1 Pro Preview (2026) are frontier reasoning models from Anthropic and Google DeepMind. Both ship a 1m-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 13.3 pts. On pricing, Claude Mythos Preview costs $25/1M input tokens; Gemini 3.1 Pro Preview ranges from $2 to $4/1M input tokens by tier. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Claude Mythos Preview is safer overall; choose Gemini 3.1 Pro Preview when coding workflow support matters.

Decision scorecard

Local evidence first
SignalClaude Mythos PreviewGemini 3.1 Pro 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$12/1M tokens
Provider routes2 tracked5 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 13.3 points.
  • Claude Mythos Preview uniquely exposes Reasoning in local model data.
  • Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
Choose Gemini 3.1 Pro Preview when...
  • Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
  • Gemini 3.1 Pro Preview has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags Gemini 3.1 Pro 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 3.1 Pro Preview

Claude Mythos Preview

$51,250

Cheapest tracked route/tier: Anthropic

Gemini 3.1 Pro Preview

$4,600

Cheapest tracked route/tier: Google AI Studio

Estimated monthly gap: $46,650. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Mythos Preview -> Gemini 3.1 Pro Preview
  • No overlapping tracked provider route is sourced for Claude Mythos Preview and Gemini 3.1 Pro Preview; plan for SDK, billing, or endpoint changes.
  • Gemini 3.1 Pro Preview is $113/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Check replacement coverage for Reasoning before moving production traffic.
Gemini 3.1 Pro Preview -> Claude Mythos Preview
  • No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
  • Claude Mythos Preview is $113/1M 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
Released2026-05-012026-02-19
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 3.1 Pro Preview
Input price$25/1M tokens
0-200,001t
$2/1M tokens
200,001t+
$4/1M tokens
Output price$125/1M tokens
0-200,001t
$12/1M tokens
200,001t+
$18/1M tokens
Providers
AnthropicMicrosoft Foundry
Google AI StudioGCP Vertex AIOpenRouterReplicate APIVercel AI Gateway

Capabilities

CapabilityClaude Mythos PreviewGemini 3.1 Pro Preview
VisionYesYes
MultimodalYesYes
ReasoningYesNo
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkClaude Mythos PreviewGemini 3.1 Pro Preview
SWE-bench Verified93.980.6
Google-Proof Q&A94.694.3
τ-bench89.276.5

Continue comparing

Model pages
Labs and families
Related comparisons

Popular comparisons for Claude Mythos Preview

Popular comparisons for Gemini 3.1 Pro Preview

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