LLM Reference

Claude Opus 4.8 vs Gemini 3.1 Pro Preview

Claude Opus 4.8 (2026) and Gemini 3.1 Pro Preview (2026) are frontier reasoning models from Anthropic and Google DeepMind. Claude Opus 4.8 ships a 1m-token context window, while Gemini 3.1 Pro Preview ships a 1m-token context window. On SWE-bench Verified, Claude Opus 4.8 leads by 8 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Claude Opus 4.8 is safer overall; choose Gemini 3.1 Pro Preview when coding workflow support matters.

Decision scorecard

Local evidence first
SignalClaude Opus 4.8Gemini 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$25/1M tokens$12/1M tokens
Provider routes6 tracked5 tracked
Shared benchmarksSWE-bench Verified leader5 shared

Decision tradeoffs

Choose Claude Opus 4.8 when...
  • Claude Opus 4.8 holds a shared-benchmark lead on SWE-bench Verified, ahead by 8 points.
  • Claude Opus 4.8 has broader tracked provider coverage for fallback and route flexibility.
  • Claude Opus 4.8 uniquely exposes Reasoning, Computer use, and Parallel agents in local model data.
  • Local decision data tags Claude Opus 4.8 for Coding, RAG, and Agents.
Choose Gemini 3.1 Pro Preview when...
  • Gemini 3.1 Pro Preview holds a shared-benchmark lead on Google-Proof Q&A, ahead by 0.7 points.
  • Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
  • 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 Opus 4.8

$10,250

Cheapest tracked route/tier: Anthropic

Gemini 3.1 Pro Preview

$4,600

Cheapest tracked route/tier: Google AI Studio

Estimated monthly gap: $5,650. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Claude Opus 4.8 -> Gemini 3.1 Pro Preview
  • Provider overlap exists on GCP Vertex AI, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
  • Gemini 3.1 Pro Preview is $13/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Check replacement coverage for Reasoning, Computer use, and Parallel agents before moving production traffic.
Gemini 3.1 Pro Preview -> Claude Opus 4.8
  • Provider overlap exists on GCP Vertex AI, OpenRouter, and Vercel AI Gateway; start route-level A/B tests there.
  • Claude Opus 4.8 is $13/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Claude Opus 4.8 adds Reasoning, Computer use, and Parallel agents in local capability data.

Specs

Specification
Released2026-05-282026-02-19
Context window1m1m
Parameters——
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeNot releasedUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2026-012025-01

Pricing and availability

Pricing attributeClaude Opus 4.8Gemini 3.1 Pro Preview
Input price$5/1M tokens
0-200,001t
$2/1M tokens
200,001t+
$4/1M tokens
Output price$25/1M tokens
0-200,001t
$12/1M tokens
200,001t+
$18/1M tokens
Providers
AnthropicAWS BedrockGCP Vertex AIMicrosoft FoundryOpenRouterVercel AI Gateway
Google AI StudioGCP Vertex AIOpenRouterReplicate APIVercel AI Gateway

Capabilities

CapabilityClaude Opus 4.8Gemini 3.1 Pro Preview
VisionYesYes
MultimodalYesYes
ReasoningYesNo
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useYesNo
Parallel agentsYesNo

Benchmarks

BenchmarkClaude Opus 4.8Gemini 3.1 Pro Preview
SWE-bench Verified88.680.6
SWE-bench Pro69.254.2
Google-Proof Q&A93.694.3
LiveCodeBench88.891.7
MCP-Atlas82.269.2

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