Gemini 3.1 Pro Preview vs Grok 4.20
Gemini 3.1 Pro Preview (2026) and Grok 4.20 (2026) are frontier reasoning models from Google DeepMind and xAI. Gemini 3.1 Pro Preview ships a 1m-token context window, while Grok 4.20 ships a 1m-token context window. On SWE-bench Verified, Gemini 3.1 Pro Preview leads by 3.9 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3.1 Pro Preview is safer overall; choose Grok 4.20 when reasoning depth matters.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | Grok 4.20 |
|---|---|---|
| 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 | Coding, RAG, and Agents |
| Context window | 1m | 1m |
| Cheapest output | $12/1M tokens | $2.50/1M tokens |
| Provider routes | 5 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 3.9 points.
- 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.
- Grok 4.20 leads the largest shared benchmark signal on τ-bench by 2.4 points.
- Grok 4.20 has the lower cheapest tracked output price at $2.50/1M tokens.
- Grok 4.20 uniquely exposes Reasoning in local model data.
- Local decision data tags Grok 4.20 for Coding, RAG, and Agents.
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
Grok 4.20
$1,625
Cheapest tracked route/tier: xAI Console
Estimated monthly gap: $2,975. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Grok 4.20 is $9.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution before moving production traffic.
- Grok 4.20 adds Reasoning in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Gemini 3.1 Pro Preview is $9.50/1M 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 Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2026-02-17 |
| Context window | 1m | 1m |
| Parameters | — | — |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2024-11 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | Grok 4.20 |
|---|---|---|
| Input price |
| $1.25/1M tokens |
| Output price |
| $2.50/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview | Grok 4.20 |
|---|---|---|
| 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
| Benchmark | Gemini 3.1 Pro Preview | Grok 4.20 |
|---|---|---|
| SWE-bench Verified | 80.6 | 76.7 |
| Google-Proof Q&A | 94.3 | 88.0 |
| τ-bench | 76.5 | 78.9 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Gemini 3.1 Pro Preview at 80.6 and Grok 4.20 at 76.7, with Gemini 3.1 Pro Preview ahead by 3.9 points; Google-Proof Q&A has Gemini 3.1 Pro Preview at 94.3 and Grok 4.20 at 88, with Gemini 3.1 Pro Preview ahead by 6.3 points; τ-bench has Gemini 3.1 Pro Preview at 76.5 and Grok 4.20 at 78.9, with Grok 4.20 ahead by 2.4 points. The largest visible gap is 6.3 points on Google-Proof Q&A, 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: Grok 4.20 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.
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 Grok 4.20 lists $1.25/1M input and $2.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok 4.20 lower by about $3.38 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 2, 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 Grok 4.20 when reasoning depth 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 has a larger context window, Gemini 3.1 Pro Preview or Grok 4.20?
Gemini 3.1 Pro Preview supports 1m tokens, while Grok 4.20 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 Grok 4.20?
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. Grok 4.20 lists $1.25/1M input and $2.50/1M 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 Grok 4.20 open source?
Gemini 3.1 Pro Preview is listed under Proprietary. Grok 4.20 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 Grok 4.20?
Both Gemini 3.1 Pro Preview and Grok 4.20 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 Grok 4.20?
Both Gemini 3.1 Pro Preview and Grok 4.20 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 Grok 4.20?
Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, Replicate API, and Vercel AI Gateway. Grok 4.20 is available on xAI Console and OpenRouter. 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.