Claude Opus 4.6 vs Gemini 3.5 Flash

Claude Opus 4.6 (2026) and Gemini 3.5 Flash (2026) are frontier-tier reasoning models from Anthropic and Google DeepMind. Claude Opus 4.6 ships a 1m-token context window, while Gemini 3.5 Flash ships a 1.05m-token context window. On SWE-bench Verified, Claude Opus 4.6 leads by 2.8 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Gemini 3.5 Flash is ~233% cheaper at $1.50/1M; pay for Claude Opus 4.6 only for coding workflow support.

Decision scorecard

Local evidence first
SignalClaude Opus 4.6Gemini 3.5 Flash
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 window1m1.05m
Cheapest output$25/1M tokens$9/1M tokens
Provider routes6 tracked4 tracked
Shared benchmarksSWE-bench Verified leader10 shared

Decision tradeoffs

Choose Claude Opus 4.6 when...
  • Claude Opus 4.6 holds a shared-benchmark lead on SWE-bench Verified, ahead by 2.8 points.
  • 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.
Choose Gemini 3.5 Flash when...
  • Gemini 3.5 Flash holds a shared-benchmark lead on SWE-bench Pro, ahead by 1.7 points.
  • Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • Gemini 3.5 Flash has the lower cheapest tracked output price at $9/1M tokens.
  • Local decision data tags Gemini 3.5 Flash 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 3.5 Flash

Claude Opus 4.6

$10,250

Cheapest tracked route/tier: Anthropic

Gemini 3.5 Flash

$3,450

Cheapest tracked route/tier: Google AI Studio

Estimated monthly gap: $6,800. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Opus 4.6 -> Gemini 3.5 Flash
  • Provider overlap exists on GCP Vertex AI, Vercel AI Gateway, and OpenRouter; start route-level A/B tests there.
  • Gemini 3.5 Flash is $16/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
Gemini 3.5 Flash -> Claude Opus 4.6
  • Provider overlap exists on GCP Vertex AI, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
  • Claude Opus 4.6 is $16/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.

Specs

Specification
Released2026-02-052026-05-19
Context window1m1.05m
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 Opus 4.6Gemini 3.5 Flash
Input price$5/1M tokens$1.50/1M tokens
Output price$25/1M tokens$9/1M tokens
Providers
AnthropicAWS BedrockGCP Vertex AIMicrosoft FoundryOpenRouterVercel AI Gateway
Google AI StudioGCP Vertex AIVercel AI GatewayOpenRouter

Capabilities

CapabilityClaude Opus 4.6Gemini 3.5 Flash
VisionYesYes
MultimodalYesYes
ReasoningYesYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkClaude Opus 4.6Gemini 3.5 Flash
SWE-bench Verified80.878.0
SWE-bench Pro53.455.1
Google-Proof Q&A91.392.2
Massive Multi-discipline Multimodal Understanding76.583.6
Humanity's Last Exam53.040.2
HumanEval95.092.0
MCP-Atlas62.783.6
MMMU Pro77.388.3
Terminal-Bench 2.065.476.2
ARC-AGI-268.872.1

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