Gemini 3.1 Pro vs o3
Gemini 3.1 Pro (2026) and o3 (2025) are frontier reasoning models from Google DeepMind and OpenAI. Gemini 3.1 Pro ships a 1M-token context window, while o3 ships a 200K-token context window. On SWE-bench Verified, Gemini 3.1 Pro leads by 8.9 pts. On pricing, Gemini 3.1 Pro costs $1.25/1M input tokens versus $2/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Gemini 3.1 Pro is ~60% cheaper at $1.25/1M; pay for o3 only for coding workflow support.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2025-03-31 |
| Context window | 1M | 200K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | - |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro | o3 |
|---|---|---|
| Input price | $1.25/1M tokens | $2/1M tokens |
| Output price | $10/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro | o3 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | No | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Gemini 3.1 Pro | 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 at 80.6 and o3 at 71.7, with Gemini 3.1 Pro ahead by 8.9 points; Google-Proof Q&A has Gemini 3.1 Pro at 94.3 and o3 at 87.7, with Gemini 3.1 Pro ahead by 6.6 points; Chatbot Arena has Gemini 3.1 Pro at 1493 and o3 at 1412, with Gemini 3.1 Pro 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, multimodal input: Gemini 3.1 Pro, reasoning mode: o3, function calling: Gemini 3.1 Pro, tool use: Gemini 3.1 Pro, and structured outputs: o3. Both models share 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 lists $1.25/1M input and $10/1M 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 $0.08 per million blended tokens. Availability is 2 providers versus 2, so concentration risk also matters.
Choose Gemini 3.1 Pro when coding workflow support, larger context windows, and lower input-token cost 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 or o3?
Gemini 3.1 Pro 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 or o3?
Gemini 3.1 Pro is cheaper on tracked token pricing. Gemini 3.1 Pro costs $1.25/1M input and $10/1M 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 or o3 open source?
Gemini 3.1 Pro 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 or o3?
Gemini 3.1 Pro 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 or o3?
Gemini 3.1 Pro 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 and o3?
Gemini 3.1 Pro is available on Google AI Studio 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: 2026-05-11. Data sourced from public model cards and provider documentation.