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.
| Metric | Gemini 3.5 Flash | Grok 4.5 |
|---|---|---|
| Intelligence (AA index) | 50 | — |
| Output speed (tokens/sec) | 168.1 | — |
| Context window | 1.0M ✓ | 500K |
| Max output | 66K | — |
| Input price / 1M | $1.5 ✓ | $2 |
| Output price / 1M | $9 | $6 ✓ |
| Released | 2026-05 | 2026-07-08 |
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.