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. On pricing, Gemini 3.1 Pro Preview costs $2/1M input tokens versus $2/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Pick Gemini 3.1 Pro Preview for coding; o3 is better when coding workflow support matters more.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | o3 |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 200K |
| Cheapest output | $12/1M tokens | $8/1M tokens |
| Provider routes | 4 tracked | 2 tracked |
| Shared benchmarks | SWE-bench Verified leader | 3 rows |
Decision tradeoffs
- Gemini 3.1 Pro Preview leads the largest shared benchmark signal on SWE-bench Verified 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 procurement flexibility.
- Gemini 3.1 Pro Preview uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
- 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 prices on this page.
Gemini 3.1 Pro Preview
$4,600
Cheapest tracked route: Google AI Studio
o3
$3,600
Cheapest tracked route: OpenAI API
Estimated monthly gap: $1,000. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- o3 is $4/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Function calling before moving production traffic.
- o3 adds Reasoning in local capability data.
- Provider overlap exists on OpenRouter; 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.
- Gemini 3.1 Pro Preview adds Vision, Multimodal, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2025-04-16 |
| Context window | 1M | 200K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2024-06 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | o3 |
|---|---|---|
| Input price | $2/1M tokens | $2/1M tokens |
| Output price | $12/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview | o3 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Gemini 3.1 Pro Preview | o3 |
|---|---|---|
| SWE-bench Verified | 80.6 | 71.7 |
| Google-Proof Q&A | 94.3 | 87.7 |
| Chatbot Arena | 1493.0 | 1412.0 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Gemini 3.1 Pro Preview at 80.6 and o3 at 71.7, with Gemini 3.1 Pro Preview ahead by 8.9 points; Google-Proof Q&A has Gemini 3.1 Pro Preview at 94.3 and o3 at 87.7, with Gemini 3.1 Pro Preview ahead by 6.6 points; Chatbot Arena has Gemini 3.1 Pro Preview at 1493 and o3 at 1412, with Gemini 3.1 Pro Preview ahead by 81 points. The largest visible gap is 81 points on Chatbot Arena, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Gemini 3.1 Pro Preview, multimodal input: Gemini 3.1 Pro Preview, reasoning mode: o3, function calling: Gemini 3.1 Pro Preview, and tool use: Gemini 3.1 Pro Preview. Both models share structured outputs and code execution, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Gemini 3.1 Pro Preview lists $2/1M input and $12/1M output tokens, while o3 lists $2/1M input and $8/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts o3 lower by about $1.2 per million blended tokens. Availability is 4 providers versus 2, so concentration risk also matters.
Choose Gemini 3.1 Pro Preview when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose o3 when coding workflow support are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 3.1 Pro Preview or o3?
Gemini 3.1 Pro Preview supports 1M tokens, while o3 supports 200K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 3.1 Pro Preview or o3?
Gemini 3.1 Pro Preview is cheaper on tracked token pricing. Gemini 3.1 Pro Preview costs $2/1M input and $12/1M output tokens. o3 costs $2/1M input and $8/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3.1 Pro Preview or o3 open source?
Gemini 3.1 Pro Preview is listed under Proprietary. o3 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 3.1 Pro Preview or o3?
Gemini 3.1 Pro Preview has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Gemini 3.1 Pro Preview or o3?
Gemini 3.1 Pro Preview has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Gemini 3.1 Pro Preview and o3?
Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, and Replicate API. o3 is available on OpenAI API and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-20. Data sourced from public model cards and provider documentation.