How to Use Grok 4 Reasoning and Live X Search
Grok 4 is xAI’s reasoning model released in July 2025, priced at $3 per million input tokens and $15 per million output tokens, with native access to live X posts and a 256K-token context window.
The live X connection is the reason to pick it over Claude or GPT for certain jobs. No other frontier model can natively search posts, replies, and reactions as they appear. Everything else, Grok 4 does well but not uniquely. So the question is whether you do work where real-time social data changes the answer.
Where do you actually use Grok 4?
- Tracking a breaking story and pulling the earliest credible posts.
- Reading sentiment around a product launch before the press covers it.
- Solving math and physics problems with visible reasoning steps.
- Summarising a long thread into a briefing.
- Coding tasks where web search and reasoning need to combine.
You reach it through grok.com, the xAI API, or X Premium+. The consumer app and the API behave differently: the API gives you raw model output, the app wraps it in tools and a friendlier interface.
How does pricing work on the API?
| Item | Price | Note |
|---|---|---|
| Input tokens | ~$3 per million | Context and prompts |
| Output tokens | ~$15 per million | Reasoning counts here too |
| Grok 4 Heavy | Higher | Runs several agents in parallel |
Reasoning mode burns output tokens because the model writes out its thinking. A single hard question can generate thousands of output tokens before the answer starts. If you are cost-sensitive, use fast mode for routine chat and reserve reasoning for problems that need it.
What is Grok 4 Heavy?
Heavy runs multiple agents in parallel and combines their work, which helps on genuinely hard problems. It also occasionally contradicts itself when the parallel agents disagree, and it costs materially more. Try it on a benchmark task before wiring it into production.
Where is Grok 4 a poor fit?
Privacy-sensitive work is the big one. X data flows through the system, and if your prompts contain confidential material you should think hard before routing them there. Long-form creative writing is also better served by Claude, and tight IDE integration by other tools. Grok 4 is a research and reasoning engine, not a general replacement.
How do you get reliable answers from it?
Ask for sources explicitly when using live search, and check the timestamps on cited posts. Ask it to show its reasoning when the answer matters, then look for the step where it jumped. Because the context window is 256K, feed it long documents rather than summaries; the model handles the raw text better.
Key Takeaways
- Grok 4 launched July 2025 with a 256K context window and vision input.
- API pricing is about $3/$15 per million input/output tokens.
- Native live X search is unique among frontier models.
- Avoid it for privacy-sensitive work; consider Claude for long-form writing.
