Grok 4 Fast (Reasoning)
xai/grok-4-fast-reasoning提供： xAI · ファミリー: grok · リリース 2025-09-19 · 知識カットオフ: 2025-07
Prices in USD per 1M tokens. Unknown means the provider does not publish per-token pricing.
機能一覧
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. |
料金詳細
推奨料金 (提供元): jiekou · grok-4-fast-reasoning
9 か所で利用可能
| プロバイダー | プロバイダーモデルID | 入力 / 1M | 出力 / 1M | コンテキスト | リリース日 |
|---|---|---|---|---|---|
| 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 |
プロバイダー間でデータに差異
- 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
プロバイダーごとに本モデルの値が異なります。上部の「主要数値」は代表的プロバイダーを使用しています。詳細は表をご確認ください。
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
最終更新：
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.