| Signal | Grok 4 Fast | Delta | Kimi K2.5 |
|---|---|---|---|
Capabilities | 100 | +17 | |
Benchmarks | 70 | +70 | |
Pricing | 1 | -2 | |
Context window size | 100 | +14 | |
Recency | 99 | -1 | |
Output Capacity | 75 | -6 | |
| Overall Result | 3 wins | of 6 | 3 wins |
5
days ranked higher
1
days
24
days ranked higher
xAI
Moonshot AI
Grok 4 Fast saves you $110.00/month
That's $1320.00/year compared to Kimi K2.5 at your current usage level of 100K calls/month.
| Metric | Grok 4 Fast | Kimi K2.5 | Winner |
|---|---|---|---|
| Overall Score | 83 | 85 | Kimi K2.5 |
| Rank | #52 | #31 | Kimi K2.5 |
| Quality Rank | #52 | #31 | Kimi K2.5 |
| Adoption Rank | #52 | #31 | Kimi K2.5 |
| Parameters | -- | -- | -- |
| Context Window | 2000K | 262K | Grok 4 Fast |
| Pricing | $0.20/$0.50/M | $0.45/$2.20/M | -- |
| Signal Scores | |||
| Capabilities | 100 | 83 | Grok 4 Fast |
| Benchmarks | 70 | -- | Grok 4 Fast |
| Pricing | 1 | 2 | Kimi K2.5 |
| Context window size | 100 | 86 | Grok 4 Fast |
| Recency | 99 | 100 | Kimi K2.5 |
| Output Capacity | 75 | 80 | Kimi K2.5 |
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 83/100 (rank #52), placing it in the top 82% of all 290 models tracked.
Scores 85/100 (rank #31), placing it in the top 90% 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 74% better value per quality point. At 1M tokens/day, you'd spend $10.50/month with Grok 4 Fast vs $39.75/month with Kimi K2.5 - a $29.25 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
Grok 4 Fast and Kimi K2.5 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
Grok 4 Fast
Marginally better benchmark scores; both are excellent
Best for Cost
Grok 4 Fast
74% lower pricing; better value at scale
Best for Reliability
Grok 4 Fast
Higher uptime and faster response speeds
Best for Prototyping
Grok 4 Fast
Stronger community support and better developer experience
Best for Production
Grok 4 Fast
Wider enterprise adoption and proven at scale
by xAI
| Capability | Grok 4 Fast | Kimi K2.5 |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoning | ||
| Web Searchdiffers | ||
| Image Output |
xAI
Moonshot AI
Grok 4 Fast saves you $2.49/month
That's 72% cheaper than Kimi K2.5 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 | Grok 4 Fast | Kimi K2.5 |
|---|---|---|
| Context Window | 2M | 262K |
| Max Output Tokens | 30,000 | 65,535 |
| Open Source | No | Yes |
| Created | Sep 19, 2025 | Jan 27, 2026 |
Kimi K2.5 scores 85/100 (rank #31) compared to Grok 4 Fast's 83/100 (rank #52), giving it a 2-point advantage. Kimi K2.5 is the stronger overall choice, though Grok 4 Fast may excel in specific areas like cost efficiency.
Grok 4 Fast is ranked #52 and Kimi K2.5 is ranked #31 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 Kimi K2.5's $2.20/M output tokens - 4.4x more expensive. Input token pricing: Grok 4 Fast at $0.20/M vs Kimi K2.5 at $0.45/M.
Grok 4 Fast has a larger context window of 2,000,000 tokens compared to Kimi K2.5's 262,144 tokens. A larger context window means the model can process longer documents and conversations.