Grok 4 Fast (free) is cheaper than Gemini 2.5 Flash Preview at $0/M vs $0.15/M input tokens.
| Spec | Gemini 2.5 Flash Preview | Grok 4 Fast (free) |
|---|---|---|
| Input price | $0.15/M tokens | Free |
| Output price | $0.6/M tokens | Free |
| Context window | 1.0M tokens | 2.0M tokens |
| Parameters | Not disclosed | Not disclosed |
| Free API (OpenRouter) | No | No |
| Released | Apr 2025 | Sep 2025 |
Not enough votes to call it. On the specs, Grok 4 Fast (free) has the edge: bigger model tier, newer, bigger context window.
Pick Gemini 2.5 Flash Preview for Web Design. Pick Grok 4 Fast (free) for Reasoning.
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Grok 4 Fast (free) uses 17.8x more headings