Gemini 3.1 Pro Preview vs Gemini Robotics-ER 1.6 Preview
Gemini 3.1 Pro Preview (2026) and Gemini Robotics-ER 1.6 Preview (2026) are frontier reasoning models from Google DeepMind. Gemini 3.1 Pro Preview ships a 1m-token context window, while Gemini Robotics-ER 1.6 Preview ships a 128k-token context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
Gemini 3.1 Pro Preview fits 8x more tokens; pick it for long-context work and Gemini Robotics-ER 1.6 Preview for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | Gemini Robotics-ER 1.6 Preview |
|---|---|---|
| Best for | multimodal apps, tool-calling agents, and long-context analysis | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | RAG, Agents, and Long context |
| Context window | 1m | 128k |
| Cheapest output | $12/1M tokens | - |
| Provider routes | 5 tracked | 0 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 broader tracked provider coverage for fallback and procurement flexibility.
- Gemini 3.1 Pro Preview uniquely exposes Code execution in local model data.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
- Gemini Robotics-ER 1.6 Preview uniquely exposes Reasoning in local model data.
- Local decision data tags Gemini Robotics-ER 1.6 Preview for RAG, Agents, and Long context.
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
Gemini Robotics-ER 1.6 Preview
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview and Gemini Robotics-ER 1.6 Preview; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Code execution before moving production traffic.
- Gemini Robotics-ER 1.6 Preview adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Gemini Robotics-ER 1.6 Preview and Gemini 3.1 Pro Preview; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Pro Preview adds Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2026-04-14 |
| Context window | 1m | 128k |
| 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 | - |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | Gemini Robotics-ER 1.6 Preview |
|---|---|---|
| Input price |
| - |
| Output price |
| - |
| Providers | - |
Capabilities
| Capability | Gemini 3.1 Pro Preview | Gemini Robotics-ER 1.6 Preview |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
| 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: Gemini Robotics-ER 1.6 Preview and code execution: 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.
Pricing coverage is uneven: Gemini 3.1 Pro Preview has $2/1M input tokens and Gemini Robotics-ER 1.6 Preview has no token price sourced yet. Provider availability is 5 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Gemini 3.1 Pro Preview when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Gemini Robotics-ER 1.6 Preview when reasoning depth are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Gemini 3.1 Pro Preview or Gemini Robotics-ER 1.6 Preview?
Gemini 3.1 Pro Preview supports 1m tokens, while Gemini Robotics-ER 1.6 Preview supports 128k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Gemini 3.1 Pro Preview or Gemini Robotics-ER 1.6 Preview open source?
Gemini 3.1 Pro Preview is listed under Proprietary. Gemini Robotics-ER 1.6 Preview 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 Gemini Robotics-ER 1.6 Preview?
Both Gemini 3.1 Pro Preview and Gemini Robotics-ER 1.6 Preview 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 Gemini Robotics-ER 1.6 Preview?
Both Gemini 3.1 Pro Preview and Gemini Robotics-ER 1.6 Preview 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 Gemini Robotics-ER 1.6 Preview?
Gemini Robotics-ER 1.6 Preview 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 Gemini Robotics-ER 1.6 Preview?
Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, Replicate API, and Vercel AI Gateway. Gemini Robotics-ER 1.6 Preview is available on the tracked providers still being sourced. 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.