Grok 4 Fast

xAI chatvisionreasoningtool_use Long

API ID: x-ai/grok-4-fast

Compare Calculate
Input Price
$0.20
/1M tokens
Output Price
$0.50
/1M tokens

About Grok 4 Fast

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Read more about the model on xAI's [news post](http://x.ai/news/grok-4-fast). Reasoning can be enabled/disabled using the `reasoning` `enabled` parameter in the API. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#controlling-reasoning-tokens)

💰
Price Ranking
#766 lowest price among 1240 Chat models

Model Specifications

Context Length
2.0M
Max Output
30k
Release Date
2025-09-19
Capabilities
chat vision reasoning tool_use
Input Modalities
textimage
Output Modalities
text

Best For

  • Complex reasoning, math problems, multi-step logic
  • Image analysis, document understanding, visual Q&A
  • Conversations, content writing, general assistance

Consider Alternatives For

  • Simple Q&A (cheaper models available)

💰 Real-World Cost Examples

Estimated monthly costs for common use cases

Personal AI Assistant
$0.24
/month
50 conversations/day, ~500 tokens each
Customer Service Bot
$7.50
/month
1000 tickets/day, ~800 tokens each
Data Analysis Pipeline
$10.50
/month
500 analyses/day, ~2k tokens each
Calculate Your Custom Usage

xAI Model Lineup

Compare all models from xAI to find the best fit

Model Input Output Context Capabilities
Grok 4 Fast Current Free Free 2.0M chat vision reasoning tool_use
Grok 2 Vision 1212 Free Free 33k chat vision
Grok 2 Vision 1212 Free Free 33k chat vision
Grok Vision Beta Free Free 8k chat vision
Grok Vision Beta Free Free 8k chat vision
Grok 2 Free Free 33k chat
View All xAI Models →

Similar Models from Other Providers

Cross-brand alternatives with similar capabilities

Meta Llama 3 70B Instruct
Meta
Input: $0.30
Output: $0.40
Context: 8k
Inclusionai Ling-2.6-1T
Inclusionai
Input: $0.07
Output: $0.63
Context: 262k
OpenAI GPT-5.6 Luna Pro
OpenAI
Input: $0.10
Output: $0.60
Context: 1.1M
OpenAI GPT-5.6 Luna Pro (batch)
OpenAI
Input: $0.10
Output: $0.60
Context: 1.1M
Compare These Models

💡 Cheaper Alternatives

Cross Brand

GTE-Base Other
$0.0050 Free 512
E5-Base-v2 Other
$0.0050 Free 512
paraphrase-MiniLM-L6-v2 Other
$0.0050 Free 512

🚀 Quick Start

Get started with Grok 4 Fast API

OpenAI-compatible SDK 
from openai import OpenAI

client = OpenAI(
    base_url="https://api.provider.com/v1",
    api_key="YOUR_API_KEY"
)

response = client.chat.completions.create(
    model="x-ai/grok-4-fast",
    messages=[
        {"role": "user", "content": "Hello!"}
    ]
)
print(response.choices[0].message.content)

Resources

Continue Your Decision

Back to xAI Add to Compare Calculate Cost