Grok 4.20 (reasoning) API cost calculator
Grok 4.20 (reasoning) (Grok (xAI)) is priced at $1.25 per million input tokens, $0.2 for cached input, and $2.50 per million output tokens. Verified 2026-09-17 against Grok (xAI)'s pricing page.
Requests with 200k or more input tokens are billed at twice these rates.
What Grok 4.20 (reasoning) costs for common workloads
| Workload | Per request | Per day | Per month |
|---|---|---|---|
| Support chatbotShort turns with a reused system prompt — 3k in, 400 out, 60% cached. | $0.0029 | $14.30 | $429 |
| RAG over documentsRetrieved context dominates — 12k in, 500 out, 30% cached. | $0.012 | $18.70 | $561 |
| Coding agentGrowing context every turn — 20k in, 1.5k out, 80% cached. | $0.012 | $35.85 | $1,076 |
| Batch classificationTiny prompts at volume through the Batch API — 800 in, 20 out. | $0.0010 | $210 | $6,300 |
Its blast radius when an agent loops
The coding-agent workload above at 30 requests a minute — $21.51 an hour — priced at each point a team usually finds out:
Hourly alert
$21.51
Next morning
$516
After a weekend
$1,291
Monthly invoice
$15,487