Grok 4 Fast (Reasoning)
xai/grok-4-fast-reasoningPor xAI · familia: grok · lanzado 2025-09-19 · fecha de conocimiento: 2025-07
Prices in USD per 1M tokens. Unknown means the provider does not publish per-token pricing.
Capacidades
Model fit scores
0–100 · higher is betterThese scores reward declared capabilities, context size, price and provider availability — they are not benchmark results. Use them as a directional signal alongside your own evaluation.
Coding79
- Tool calling40/40
- Structured output0/20
- Reasoning10/10
- Context window (100K → 1M)20/20
- Provider availability9/10
Agents74
- Tool calling35/35
- Structured output0/25
- Reasoning15/15
- Output token limit15/15
- Provider availability9/10
JSON / structured output49
- Structured output / JSON mode0/50
- Tool calling20/20
- Temperature control10/10
- Price-friendly for high-volume19/20
Cost efficiency67
- Headline price (log-scaled)67/95
- Has prompt-cache pricing0/5
Long context100
- Context window (100K → 2M)90/90
- Has published price for full window10/10
Vision99
- Accepts image input50/50
- Context window (10K → 1M)30/30
- Has published price10/10
- Provider availability9/10
Production-readiness96
- Number of independent providers40/40
- Has published per-token price20/20
- Context window ≥ 8K15/15
- No data inconsistencies across providers6/10
- Official model (not derivative)15/15
Cost Efficiency Index
Open full calculator →Estimated cost using the recommended provider's headline rate. Each scenario fixes average input/output tokens — the assumptions are shown in the third column.
| Scenario | Cost | Assumption |
|---|---|---|
RAG answer per 1,000 RAG answers | $1.13 < $0.01 per request | 5K input tokens (query + 4 retrieved chunks of ~1K each) and a 500-token answer. Typical SaaS knowledge-base bot. |
Support ticket triage per 10,000 tickets | $2.25 < $0.01 per request | 1K input tokens (ticket body + system prompt) and a 100-token JSON classification reply. High-volume customer support. |
Data extraction per 1,000 documents | $0.58 < $0.01 per request | 2K input tokens (a single document page) and a 500-token JSON extraction. ETL / invoice / form pipelines. |
Code review per 1,000 PRs | $1.89 < $0.01 per request | 8K input tokens (diff + surrounding files) and a 1K-token review comment. PR-bot workloads. |
Agent step per 1,000 steps | $2.43 < $0.01 per request | 12K input tokens (long-running tool history) and a 600-token tool-call decision. Cost per agent step. |
Detalle de precios
Precio recomendado de jiekou · grok-4-fast-reasoning
Disponible en 9 proveedores
| Proveedor | ID de modelo del proveedor | Entrada / 1M | Salida / 1M | Contexto | Lanzado |
|---|---|---|---|---|---|
| Azure azure | grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-09-19 |
| Vercel AI Gateway vercel | xai/grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-07-09 |
| 302.AI 302ai | grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-09-23 |
| Jiekou.AI jiekou | grok-4-fast-reasoning | $0.180 | $0.450 | 2M | 2026-01 |
| Qiniu qiniu-ai | x-ai/grok-4-fast-reasoning | Unknown | Unknown | 2M | 2025-12-18 |
| Poe poe | xai/grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-09-16 |
| Helicone helicone | grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-09-01 |
| Azure Cognitive Services azure-cognitive-services | grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-09-19 |
| LLM Gateway llmgateway | grok-4-fast-reasoning | $0.200 | $0.500 | 2M | 2025-07-09 |
Inconsistencias de datos entre proveedores
- release_date varies (span 176d): 2025-07-09, 2025-09-01, 2025-09-16, 2025-09-19, 2025-09-23, 2025-12-18, 2026-01
- modalities varies across offerings
Los proveedores reportan valores distintos para este modelo. Los datos clave de arriba usan un proveedor representativo; consulta la tabla para detalles por proveedor.
Frequently asked questions
How much does Grok 4 Fast (Reasoning) cost?
Grok 4 Fast (Reasoning) costs $0.180 per 1M input tokens and $0.450 per 1M output tokens, sourced from jiekou. Cache reads, audio tokens and >200K-context tiers (where applicable) are listed in the Pricing detail block above.
What is the context window of Grok 4 Fast (Reasoning)?
Grok 4 Fast (Reasoning) has a context window of 2M tokens, with a max output of 30K tokens per reply. This is the total combined size of prompt + completion.
Does Grok 4 Fast (Reasoning) support tool calling?
Yes. Grok 4 Fast (Reasoning) supports tool calling (function calling). This makes it suitable for production agent and automation workloads where the model has to invoke external functions reliably.
Does Grok 4 Fast (Reasoning) support structured output / JSON mode?
Support for structured output / JSON-schema-constrained decoding is not reported for Grok 4 Fast (Reasoning) in our data source. Verify with xAI's official documentation before relying on it in production.
Can Grok 4 Fast (Reasoning) accept image input?
Yes. Grok 4 Fast (Reasoning) accepts both text and image input. Vision pricing per image is usually billed on top of the regular token rate — check xAI's docs for the exact rule.
Is Grok 4 Fast (Reasoning) open-weight?
No. Grok 4 Fast (Reasoning) is a proprietary model — only xAI (and any approved hosting partners) can serve it. The pricing above reflects the cheapest API access.
What are the best alternatives to Grok 4 Fast (Reasoning)?
If Grok 4 Fast (Reasoning) doesn't fit, consider Grok Code Fast 1, Grok 4.1 Fast (Non-Reasoning), Grok 4. Each one targets the same use case — see the Related links below for direct head-to-head pages.
Where does this data come from?
All numbers come from the public models.dev API and are normalised into a single canonical model record. We re-pull daily and write any changes (price, context, capability) to the /changelog page.
Explore more
More xAI models
- Grok Code Fast 1$0.20 in / $1.50 out
- Grok 4.1 Fast (Non-Reasoning)$0.20 in / $0.50 out
- Grok 4$3.00 in / $15.00 out
- Grok 4 Fast (Non-Reasoning)$0.20 in / $0.50 out
- Grok 4.1 Fast (Reasoning)$0.18 in / $0.45 out
Capability lists this model is in
Última actualización:
Data is sourced from models.dev and normalized for comparison. Prices and capabilities may change. Always verify critical production decisions with the provider's official documentation.