| Signal | GPT-5.1 Chat | Delta | Grok 4 Fast |
|---|---|---|---|
Capabilities | 83 | -17 | |
Pricing | 10 | +10 | |
Context window size | 81 | -19 | |
Recency | 100 | +1 | |
Output Capacity | 70 | -4 | |
Benchmarks | 0 | -70 | |
| Overall Result | 2 wins | of 6 | 4 wins |
14
days ranked higher
3
days
13
days ranked higher
OpenAI
xAI
Grok 4 Fast saves you $580.00/month
That's $6960.00/year compared to GPT-5.1 Chat at your current usage level of 100K calls/month.
| Metric | GPT-5.1 Chat | Grok 4 Fast | Winner |
|---|---|---|---|
| Overall Score | 85 | 83 | GPT-5.1 Chat |
| Rank | #36 | #52 | GPT-5.1 Chat |
| Quality Rank | #36 | #52 | GPT-5.1 Chat |
| Adoption Rank | #36 | #52 | GPT-5.1 Chat |
| Parameters | -- | -- | -- |
| Context Window | 128K | 2000K | Grok 4 Fast |
| Pricing | $1.25/$10.00/M | $0.20/$0.50/M | -- |
| Signal Scores | |||
| Capabilities | 83 | 100 | Grok 4 Fast |
| Pricing | 10 | 1 | GPT-5.1 Chat |
| Context window size | 81 | 100 | Grok 4 Fast |
| Recency | 100 | 99 | GPT-5.1 Chat |
| Output Capacity | 70 | 75 | Grok 4 Fast |
| Benchmarks | -- | 70 | Grok 4 Fast |
Our composite score (0–100) combines six weighted signals: benchmark performance (25%), pricing efficiency (25%), context window size (15%), model recency (15%), output capacity (10%), and capability versatility (10%). Here's what the scores mean for these two models:
Scores 85/100 (rank #36), placing it in the top 88% of all 290 models tracked.
Scores 83/100 (rank #52), placing it in the top 82% of all 290 models tracked.
With only a 2-point gap, these models are in the same performance tier. The practical difference in output quality is minimal - your choice should depend on pricing, latency requirements, and specific feature needs.
Grok 4 Fast offers 94% better value per quality point. At 1M tokens/day, you'd spend $10.50/month with Grok 4 Fast vs $168.75/month with GPT-5.1 Chat - a $158.25 monthly difference.
Both models have comparable response speeds. For most applications, the latency difference is negligible.
When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.
Code generation & review
Higher benchmark score (0/100) indicates stronger performance on coding tasks like generating functions, debugging, and refactoring
Customer support chatbot
Faster response time (speed score 0/100) is critical for user-facing chat. Grok 4 Fast also offers lower per-token costs for high-volume support
Long document analysis
Larger context window (2000K tokens) can process longer documents, contracts, and research papers in a single pass
Batch data extraction
Lower output pricing ($0.50/M) reduces costs when processing thousands of records daily
Creative writing & content
Higher overall composite score (85/100) correlates with better nuance, coherence, and style in long-form content
Image understanding & OCR
Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly
GPT-5.1 Chat and Grok 4 Fast are extremely close in overall performance (only 1.5999999999999943 points apart). Your best choice depends entirely on which specific strengths matter most for your use case.
Best for Quality
GPT-5.1 Chat
Marginally better benchmark scores; both are excellent
Best for Cost
Grok 4 Fast
94% lower pricing; better value at scale
Best for Reliability
GPT-5.1 Chat
Higher uptime and faster response speeds
Best for Prototyping
GPT-5.1 Chat
Stronger community support and better developer experience
Best for Production
GPT-5.1 Chat
Wider enterprise adoption and proven at scale
by OpenAI
| Capability | GPT-5.1 Chat | Grok 4 Fast |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoningdiffers | ||
| Web Search | ||
| Image Output |
OpenAI
xAI
Grok 4 Fast saves you $13.29/month
That's 93% cheaper than GPT-5.1 Chat at 1,000 tokens/request and 100 requests/day.
Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.
| Parameter | GPT-5.1 Chat | Grok 4 Fast |
|---|---|---|
| Context Window | 128K | 2M |
| Max Output Tokens | 16,384 | 30,000 |
| Open Source | No | No |
| Created | Nov 13, 2025 | Sep 19, 2025 |
GPT-5.1 Chat scores 85/100 (rank #36) compared to Grok 4 Fast's 83/100 (rank #52), giving it a 2-point advantage. GPT-5.1 Chat is the stronger overall choice, though Grok 4 Fast may excel in specific areas like cost efficiency.
GPT-5.1 Chat is ranked #36 and Grok 4 Fast is ranked #52 out of 290+ AI models. Rankings use a composite score combining benchmark performance (25%), pricing (25%), context window (15%), recency (15%), output capacity (10%), and versatility (10%). Scores update hourly.
Grok 4 Fast is cheaper at $0.50/M output tokens vs GPT-5.1 Chat's $10.00/M output tokens - 20.0x more expensive. Input token pricing: GPT-5.1 Chat at $1.25/M vs Grok 4 Fast at $0.20/M.
Grok 4 Fast has a larger context window of 2,000,000 tokens compared to GPT-5.1 Chat's 128,000 tokens. A larger context window means the model can process longer documents and conversations.