Model Comparison
Grok 4 Fast (Reasoning)
vs. Kimi K2
Comparing 2 AI models · 12 benchmarks · xAI, MoonshotAI
Recommended Pick
xA Grok 4 Fast (Reasoning) 20 metric wins Strongest on: Value, Input price, Output price
Best Value
Grok 4 Fast (Reasoning)
100.0 value score
63.2 reasoning / $0.28/1M
Lowest Price
Grok 4 Fast (Reasoning)
$0.20/1M input price
Best Reasoning
Grok 4 Fast (Reasoning)
63.2 reasoning score
Blends available reasoning benchmarks
Best for Coding
Grok 4 Fast (Reasoning)
27.4 coding index
Composite Indices
Higher is better; speed and price are normalized
Standard Benchmarks
Only benchmarks with data are shown
Differences That Matter
Best value
Grok 4 Fast (Reasoning) has the strongest quality-to-price mix at 100.0 out of 100 value points.
Price gap
Grok 4 Fast (Reasoning) is 2.9x cheaper on input tokens than Kimi K2.
Reasoning gap
Grok 4 Fast (Reasoning) leads Kimi K2 by 7.5 points on reasoning.
Coding gap
Grok 4 Fast (Reasoning) leads Kimi K2 by 5.3 points on coding.
Top-pick rationale
Grok 4 Fast (Reasoning) wins 20 measurable categories, including Value, Input price, Output price, Blended price.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Grok 4 Fast (Reasoning)
xAI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Kimi K2
MoonshotAI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Which answer was more useful?
Full Comparison
| Metric | Top Pick xA Grok 4 Fast (Reasoning) | Mo Kimi K2 |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.20/1M | $0.58/1M |
| Output Cost | $0.50/1M | $2.40/1M |
| Blended (3:1) | $0.28/1M | $1.04/1M |
| Specifications | ||
| Organization | xAI | MoonshotAI |
| Release Date | Sep 19, 2025 | Jul 11, 2025 |
| Performance & Speed | ||
| Throughput | — | 22.9 tok/s |
| TTFT | — | 1541ms |
| Latency | — | 1541ms |
| Composite Indices | ||
| Value Score | 100.0 | 23.3 |
| Reasoning Score | 63.2 | 55.8 |
| Intelligence | 35.1 | 26.3 |
| Coding | 27.4 | 22.1 |
| Math | 89.7 | 57.0 |
| Standard Benchmarks | ||
| GPQA | 84.7% | 76.6% |
| MMLU Pro | 85.0% | 82.4% |
| HLE | 17.0% | 7.0% |
| LiveCodeBench | 83.2% | 55.6% |
| MATH 500 | — | 97.1% |
| AIME 2025 | 89.7% | 57.0% |
| AIME (Original) | — | 69.3% |
| SciCode | 44.2% | 34.5% |
| LCR | 64.7% | 51.0% |
| IFBench | 50.5% | 41.5% |
| TAU-bench v2 | 65.8% | 61.1% |
| TerminalBench Hard | 18.9% | 15.9% |
Key Takeaways
Grok 4 Fast (Reasoning) offers the best value at $0.20/1M, making it ideal for high-volume applications and cost-conscious projects.
Grok 4 Fast (Reasoning) has the strongest reasoning profile with a 63.2 reasoning score, combining the available reasoning-heavy benchmarks.
Grok 4 Fast (Reasoning) reaches a 27.4 coding index, making it the top choice for software development and code generation tasks.
All models support context windows of ∞+ tokens, suitable for processing lengthy documents and maintaining extended conversations.
When to Choose Each Model
Grok 4 Fast (Reasoning)
- Cost-sensitive applications
- High-volume processing
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
Kimi K2
- General-purpose AI
- Versatile applications
