Model comparison
Grok 3 vs Grok 4 Fast
Compare published model capabilities and API prices.
xAI
Grok 3
Grok model for agentic tool use, reasoning, coding, and live assistance
xAI
Grok 4 Fast
Fast Grok model for responsive chat, reasoning, and tool-assisted work
| Metric | Grok 3 | Grok 4 Fast |
|---|---|---|
| Provider | xAI | xAI |
| Context window | 128,000 | 2,000,000 |
| Input $/Mtok | $0 | $0.200 |
| Output $/Mtok | $0 | $0.500 |
| Modalities | text | text, vision |
| License | closed | closed |
Quick take
On input price, Grok 3 is cheaper at $0/Mtok. For context window, Grok 4 Fast leads with 2,000,000 tokens.
Pick based on your workload: high-volume cheap inference vs long-document / agent loops. Enterprise DNA can wire either model into Omni with evals, secrets, and job orchestration.