Gemini 3.1 Pro Preview vs GPT-5.5
Gemini 3.1 Pro Preview (2026) and GPT-5.5 (2026) are frontier reasoning models from Google DeepMind and OpenAI. Gemini 3.1 Pro Preview ships a 1M-token context window, while GPT-5.5 ships a 1.1M-token context window. On SWE-bench Verified, GPT-5.5 leads by 8.1 pts. On pricing, Gemini 3.1 Pro Preview costs $2/1M input tokens versus $5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Gemini 3.1 Pro Preview is ~150% cheaper at $2/1M; pay for GPT-5.5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | GPT-5.5 |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 1.1M |
| Cheapest output | $12/1M tokens | $30/1M tokens |
| Provider routes | 4 tracked | 2 tracked |
| Shared benchmarks | 4 rows | SWE-bench Verified leader |
Decision tradeoffs
- Gemini 3.1 Pro Preview leads the largest shared benchmark signal on Google-Proof Q&A by 0.7 points.
- Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
- Gemini 3.1 Pro Preview has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
- GPT-5.5 leads the largest shared benchmark signal on SWE-bench Verified by 8.1 points.
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 uniquely exposes Reasoning in local model data.
- Local decision data tags GPT-5.5 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
GPT-5.5
$11,500
Cheapest tracked route: OpenAI API
Estimated monthly gap: $6,900. 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.
- GPT-5.5 is $18/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.5 adds Reasoning in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Gemini 3.1 Pro Preview is $18/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2026-04-23 |
| Context window | 1M | 1.1M |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2025-12 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | GPT-5.5 |
|---|---|---|
| Input price | $2/1M tokens | $5/1M tokens |
| Output price | $12/1M tokens | $30/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview | GPT-5.5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
Benchmarks
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.5 |
|---|---|---|
| SWE-bench Verified | 80.6 | 88.7 |
| Google-Proof Q&A | 94.3 | 93.6 |
| Chatbot Arena | 1493.0 | 1488.0 |
| SWE-bench Pro | 54.2 | 58.6 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Gemini 3.1 Pro Preview at 80.6 and GPT-5.5 at 88.7, with GPT-5.5 ahead by 8.1 points; Google-Proof Q&A has Gemini 3.1 Pro Preview at 94.3 and GPT-5.5 at 93.6, with Gemini 3.1 Pro Preview ahead by 0.7 points; Chatbot Arena has Gemini 3.1 Pro Preview at 1493 and GPT-5.5 at 1488, with Gemini 3.1 Pro Preview ahead by 5 points. The largest visible gap is 8.1 points on SWE-bench Verified, 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 reasoning mode: GPT-5.5. Both models share vision, multimodal input, function calling, and tool use, 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 GPT-5.5 lists $5/1M input and $30/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Pro Preview lower by about $7.5 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, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.5 when coding workflow support and larger context windows 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 GPT-5.5?
GPT-5.5 supports 1.1M tokens, while Gemini 3.1 Pro Preview supports 1M 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 GPT-5.5?
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. GPT-5.5 costs $5/1M input and $30/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3.1 Pro Preview or GPT-5.5 open source?
Gemini 3.1 Pro Preview is listed under Proprietary. GPT-5.5 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 GPT-5.5?
Both Gemini 3.1 Pro Preview and GPT-5.5 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Gemini 3.1 Pro Preview or GPT-5.5?
Both Gemini 3.1 Pro Preview and GPT-5.5 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 3.1 Pro Preview and GPT-5.5?
Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, and Replicate API. GPT-5.5 is available on OpenAI API and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.