Gemini 3.1 Pro Preview vs o3

Gemini 3.1 Pro Preview (2026) and o3 (2025) are frontier reasoning models from Google DeepMind and OpenAI. Gemini 3.1 Pro Preview ships a 1m-token context window, while o3 ships a 200k-token context window. On SWE-bench Verified, Gemini 3.1 Pro Preview leads by 8.9 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Pick Gemini 3.1 Pro Preview for coding; o3 is better when coding workflow support matters more.

Decision scorecard

Local evidence first
SignalGemini 3.1 Pro Previewo3
Best formultimodal apps, tool-calling agents, and long-context analysisreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m200k
Cheapest output$12/1M tokens$8/1M tokens
Provider routes5 tracked3 tracked
Shared benchmarksSWE-bench Verified leader8 shared

Decision tradeoffs

Choose Gemini 3.1 Pro Preview when...
  • Gemini 3.1 Pro Preview holds a shared-benchmark lead on SWE-bench Verified, ahead by 8.9 points.
  • Gemini 3.1 Pro Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • 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.
Choose o3 when...
  • o3 holds a shared-benchmark lead on HumanEval, ahead by 2.7 points.
  • o3 has the lower cheapest tracked output price at $8/1M tokens.
  • o3 uniquely exposes Reasoning in local model data.
  • Local decision data tags o3 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 o3

Gemini 3.1 Pro Preview

$4,600

Cheapest tracked route/tier: Google AI Studio

o3

$3,600

Cheapest tracked route/tier: OpenAI API

Estimated monthly gap: $1,000. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Gemini 3.1 Pro Preview -> o3
  • Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
  • o3 is $4/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • o3 adds Reasoning in local capability data.
o3 -> Gemini 3.1 Pro Preview
  • Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
  • Gemini 3.1 Pro Preview is $4/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Check replacement coverage for Reasoning before moving production traffic.

Specs

Specification
Released2026-02-192025-04-16
Context window1m200k
Parameters——
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2025-012024-06

Pricing and availability

Pricing attributeGemini 3.1 Pro Previewo3
Input price
0-200,001t
$2/1M tokens
200,001t+
$4/1M tokens
$2/1M tokens
Output price
0-200,001t
$12/1M tokens
200,001t+
$18/1M tokens
$8/1M tokens
Providers
Google AI StudioGCP Vertex AIOpenRouterReplicate APIVercel AI Gateway
OpenAI APIOpenRouterVercel AI Gateway

Capabilities

CapabilityGemini 3.1 Pro Previewo3
VisionYesYes
MultimodalYesYes
ReasoningNoYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkGemini 3.1 Pro Previewo3
SWE-bench Verified80.671.7
Google-Proof Q&A94.387.7
AIME 202595.088.9
LiveCodeBench91.785.5
Humanity's Last Exam51.420.3
HumanEval94.096.7
Chatbot Arena1493.01412.0
MMMU Pro88.276.4

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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.