Head to head

Gemini 3.1 Pro Preview vs Grok 4.5

Gemini 3.1 Pro Preview (Google) and Grok 4.5 (xAI) compared on intelligence, speed, context, and price — and which to choose. Both run on just4o.chat from one chat.

MetricGemini 3.1 Pro PreviewGrok 4.5
Intelligence (AA index)46
Output speed (tokens/sec)137.9
Context window1.0M500K
Max output66K
Input price / 1M$2$2
Output price / 1M$12$6
Released2026-02-192026-07-08

Choose Gemini 3.1 Pro Preview if you want…

  • Larger context window (1.0M)

Choose Grok 4.5 if you want…

  • Lower price ($3 / 1M blended)

Gemini 3.1 Pro Preview

At the top of the Artificial Analysis Intelligence Index — ahead of every other model evaluated — Gemini 3.1 Pro Preview earns its ranking not just on raw ability but on the economics of getting there. It ran a full benchmark suite at less than half the cost of comparable frontier models, which makes it the clearest answer to the question of whether top-tier intelligence requires top-tier spend. A 38-percentage-point drop in hallucination rate over its predecessor and a 94.3% GPQA Diamond score in graduate-level scientific reasoning make it a serious tool for complex research, deep software engineering, and agentic workflows that need to get things right. Its 1-million-token context window handles entire codebases or lengthy document sets without batching. The honest caveat: time-to-first-token averages nearly 25 seconds, well above the median for comparable models, and some developers report extended waits or reliability issues under high API load. If your work is iterative and deep rather than real-time and conversational, the trade-off is usually worth it.

Full Gemini 3.1 Pro Preview details →

FAQ

Which is better, Gemini 3.1 Pro Preview or Grok 4.5?

Gemini 3.1 Pro Preview leads on 1 of the headline metrics (larger context window (1.0m)), while Grok 4.5 wins on lower price ($3 / 1m blended). The right pick depends on whether you prioritise capability, speed, or cost.

Is Gemini 3.1 Pro Preview or Grok 4.5 cheaper?

Grok 4.5 is cheaper at $3 per 1M tokens (blended), versus $4.5.

Can I use both Gemini 3.1 Pro Preview and Grok 4.5?

Yes. Both are available on just4o.chat from a single chat — you can switch between them per message with no separate subscriptions.