Head to head

Gemini 3.5 Flash vs Grok 4.5

Gemini 3.5 Flash (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 3.5 FlashGrok 4.5
Intelligence (AA index)50
Output speed (tokens/sec)168.1
Context window1.0M500K
Max output66K
Input price / 1M$1.5$2
Output price / 1M$9$6
Released2026-052026-07-08

Choose Gemini 3.5 Flash if you want…

  • Larger context window (1.0M)

Choose Grok 4.5 if you want…

  • Lower price ($3 / 1M blended)

Gemini 3.5 Flash

The first Flash-tier model to outperform a Pro on coding and agentic benchmarks, Gemini 3.5 Flash rewrites expectations for what a speed-optimized model can do. At over 280 tokens per second — roughly 4x faster than comparable frontier models — it sustains the throughput that production agent loops demand, while benchmark results on Terminal-Bench 2.1 (76.2%) and MCP Atlas (83.6%) put it ahead of Gemini 3.1 Pro on the tasks developers actually care about. Early users call it "an insane value" for delivering near-frontier intelligence at roughly a third of Pro's cost. The 31-point drop in hallucination rate over its predecessor makes it meaningfully more reliable in practice. The honest caveat: time to first token sits around 19 seconds, which stings in latency-sensitive interactions, and aggressive rate limiting has frustrated users hitting it hard. Deep reasoning, hard analytical problems, and ultra-long context retrieval still favor the Pro. But for teams running iterative coding agents, structured data pipelines, or high-throughput chatbots where cost and speed are the binding constraints, Flash 3.5 is the practical choice.

Full Gemini 3.5 Flash details →

FAQ

Which is better, Gemini 3.5 Flash or Grok 4.5?

Gemini 3.5 Flash 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 3.5 Flash or Grok 4.5 cheaper?

Grok 4.5 is cheaper at $3 per 1M tokens (blended), versus $3.38.

Can I use both Gemini 3.5 Flash 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.