xAI

Grok 4 Fast Reasoning

Type
language model
Context
2,000K tokens
Max output
128K
Released
16 September 2025
API string
xai/grok-4-fast-reasoning

Prices by provider

Provider Input, $ per 1M Output, $ per 1M In our data since
Jiekou.AI $0.18 $0.45 31 Jul 2026
302.AI $0.2 $0.5 31 Jul 2026
Helicone $0.2 $0.5 31 Jul 2026
Microsoft Foundry $0.2 $0.5 31 Jul 2026
Poe $0.2 $0.5 31 Jul 2026
xAI $0.2 $0.5 31 Jul 2026

Only the base tier and only per-token prices are shown. Batch, discounted and cached rates, as well as prices per image or per second of video, do not go into this table: they cannot stand in the same column as a price per million tokens.

The date in the last column is the day this price first entered our collection. The price may well be older: before that day we simply were not recording it. It has not changed since — otherwise a new row with a new date would stand in its place.

Measurement results

Task set Result Run conditions Measured by
Arena Score in French 1,433.69 1,398–1,470
Arena Score, programming 1,418.56 1,409–1,428
Arena Score in Spanish 1,411.24 1,385–1,437
Arena Score, long queries 1,410.64 1,402–1,420
Arena Score, expert questions 1,407.49 1,388–1,427
Arena Score in English 1,407.02 1,400–1,414
Arena Score, multi-turn dialogue 1,404.52 1,394–1,415
Arena Score, hard prompts 1,403.28 1,397–1,410
Arena Score, mathematics 1,403.28 1,386–1,421
Arena Score, overall 1,397.85 1,393–1,403
Arena Score in Russian 1,390.48 1,373–1,408
Arena Score, instruction following 1,381.66 1,373–1,390
Arena Score, creative writing 1,374.71 1,363–1,386
Arena Score, web development 1,160.41 1,133–1,188