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grok-4-fast-reasoning

xai·xai/grok-4-fast-reasoning-2·GA·Closed·grok series

Fast Grok model for responsive chat, reasoning, and tool-assisted work

At a glance
Reference price$0.20 / $0.50 per 1M
Cache read $0.05 · Poe
Lowest paid$0.18 / $0.45
Jiekou.AI Gateway · 1.1× spread
Context2,000,000
Output limit128,000
Capabilities
ReasoningTool useStructured outputTemperatureAttachments
⚠ Providers report capability flags inconsistently
Modalities
TextImage
Knowledge cutoff2025-06
Released / updated2026-01 / 2026-01

Quality & performance

Artificial Analysis doesn't cover this model (267 of 2059 have data). Quality data comes from independent evals covering widely used models.

Available at 3 providers3 with public prices

ProviderTierInputOutputCache readCache writeContextOutput limitStatus
Jiekou.AI
grok-4-fast-reasoning
Gateway$0.18$0.452,000,0002,000,000
302.AI
grok-4-fast-reasoning
Gateway$0.20$0.502,000,00030,000
Poe
xai/grok-4-fast-reasoning
Gateway$0.20$0.50$0.052,000,000128,000

Sorted by blended price (input×0.75 + output×0.25) asc. The official channel always shows regardless of rank. Whether a gateway's low price is actually usable can't be verified.

Your usage cost

1Poe$47.00
2Jiekou.AI$58.50
3302.AI$65.00
The cheapest paid channel is the only channel.

Benchmark

No upstream benchmark data for this model. For quality, see the Artificial Analysis intelligence score above.

Reasoning control

Upstream provides no control info

2 / 3 providers expose no reasoning control (reasoning_options: []).

Related models

Price historyone sample accumulated per data sync

Input listOutput listMin blended
$0.50$02026-08-052026-08-132026-08-05 · Input list $0.202026-08-06 · Input list $0.202026-08-07 · Input list $0.202026-08-08 · Input list $0.202026-08-09 · Input list $0.202026-08-10 · Input list $0.202026-08-11 · Input list $0.202026-08-12 · Input list $0.202026-08-13 · Input list $0.202026-08-05 · Output list $0.502026-08-06 · Output list $0.502026-08-07 · Output list $0.502026-08-08 · Output list $0.502026-08-09 · Output list $0.502026-08-10 · Output list $0.502026-08-11 · Output list $0.502026-08-12 · Output list $0.502026-08-13 · Output list $0.502026-08-05 · Min blended $0.2752026-08-06 · Min blended $0.2752026-08-07 · Min blended $0.2752026-08-08 · Min blended $0.2752026-08-09 · Min blended $0.2752026-08-10 · Min blended $0.2752026-08-11 · Min blended $0.2752026-08-12 · Min blended $0.2752026-08-13 · Min blended $0.247