Gemini 3.1 Pro Preview vs GPT-5.2 Codex
Gemini 3.1 Pro Preview (2026) and GPT-5.2 Codex (2025) compare a standalone API model against a coding-specialized model. Gemini 3.1 Pro Preview ships a 1m-token context window, while GPT-5.2 Codex ships a not-yet-sourced context window. On pricing, Gemini 3.1 Pro Preview ranges from $2 to $4/1M input tokens by tier; GPT-5.2 Codex costs $1.75/1M input tokens. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: Gemini 3.1 Pro Preview is standalone API model, while GPT-5.2 Codex is coding-specialized model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | GPT-5.2 Codex |
|---|---|---|
| Product type | Standalone API model | Coding-specialized model |
| Best for | multimodal apps, tool-calling agents, and long-context analysis | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, RAG, and Agents | Coding, Agents, and Vision |
| Context window | 1m | — |
| Cheapest output | $12/1M tokens | $14/1M tokens |
| Provider routes | 5 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Gemini 3.1 Pro Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- 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.
- Gemini 3.1 Pro Preview uniquely exposes Structured outputs in local model data.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
- GPT-5.2 Codex uniquely exposes Reasoning in local model data.
- Local decision data tags GPT-5.2 Codex for Coding, Agents, and Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3.1 Pro Preview
$4,600
Cheapest tracked route/tier: Google AI Studio
GPT-5.2 Codex
$4,900
Cheapest tracked route/tier: Vercel AI Gateway
Estimated monthly gap: $300. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.2 Codex is $2/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Structured outputs before moving production traffic.
- GPT-5.2 Codex adds Reasoning in local capability data.
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- Gemini 3.1 Pro Preview is $2/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Pro Preview adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2025-12-18 |
| Context window | 1m | — |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-01 | 2025-08 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | GPT-5.2 Codex |
|---|---|---|
| Input price |
| $1.75/1M tokens |
| Output price |
| $14/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview | GPT-5.2 Codex |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: GPT-5.2 Codex and structured outputs: Gemini 3.1 Pro Preview. 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 tiered pricing: 0-200,001t is $2/1M input and $12/1M output; 200,001t+ is $4/1M input and $18/1M output, while GPT-5.2 Codex lists $1.75/1M input and $14/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 3.1 Pro Preview lower by about $0.42 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 5 providers versus 1, so concentration risk also matters.
Choose Gemini 3.1 Pro Preview when coding workflow support and broader provider choice are central to the workload. Choose GPT-5.2 Codex when coding workflow support and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which is cheaper, Gemini 3.1 Pro Preview or GPT-5.2 Codex?
Gemini 3.1 Pro Preview lists tiered pricing: 0-200,001t is $2/1M input and $12/1M output; 200,001t+ is $4/1M input and $18/1M output. GPT-5.2 Codex lists $1.75/1M input and $14/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3.1 Pro Preview or GPT-5.2 Codex open source?
Gemini 3.1 Pro Preview is listed under Proprietary. GPT-5.2 Codex 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-5.2 Codex?
Both Gemini 3.1 Pro Preview and GPT-5.2 Codex expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Gemini 3.1 Pro Preview or GPT-5.2 Codex?
Both Gemini 3.1 Pro Preview and GPT-5.2 Codex expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Gemini 3.1 Pro Preview or GPT-5.2 Codex?
GPT-5.2 Codex has the clearer documented reasoning mode signal in this comparison. If reasoning mode 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 GPT-5.2 Codex?
Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, Replicate API, and Vercel AI Gateway. GPT-5.2 Codex is available on Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.