--- title: When to use which Gemini mode date: '2026-02-02T08:15:16+08:00' categories: - llms description: Fast, Thinking, and Pro are best treated as task-specific Gemini modes rather than generic quality tiers, because each one fits a different kind of job. keywords: [Gemini, model modes, task selection, prompting, productivity, AI workflows] --- I continue to be impressed by Gemini 3 and it's become my default agent. It writes in simpler language than ChatGPT (almost as eloquent as Claude), has much larger limits, and, of course, is [unbeaten at generating images](https://www.s-anand.net/blog/gemini-copies-images-almost-perfectly/). The Gemini app has 3 modes: Fast, Thinking, and Pro. Here's when to use each: 1. **Simple task**, e.g., grammar check, translate, summarize, or basic question? Use **Fast**. Pro overthinks. 2. **Multi-step logic**, e.g., planning a trip with constraints, checking 15 emails, or identifying a subtle error in code? Use **Thinking**. Flash-based thinking beats Pro. 3. **Large input**, e.g. 300-page PDF, 2 hours of video, etc.? Use **Pro**. It uses the 1M+ token window well. 4. **Complex problem**, e.g. PhD-level science or a legal contract review, with high stakes? Use **Pro**. If you hit your Pro limit (which is pretty high!), just switch to **Thinking**, which is smart enough for most jobs anyway. Source: [Gemini](https://gemini.google.com/share/bdf6152e772d)