Model Comparison
GPT-4o (ChatGPT)
vs. Grok 4 Fast (Reasoning)
Comparing 2 AI models · 12 benchmarks · OpenAI, xAI
Recommended Pick
xA Grok 4 Fast (Reasoning) 7 metric wins Strongest on: Reasoning, Intelligence, GPQA
Lowest Price
GPT-4o (ChatGPT)
$0.00/1M 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
Price gap
GPT-4o (ChatGPT) is ∞x cheaper on input tokens than Grok 4 Fast (Reasoning).
Reasoning gap
Grok 4 Fast (Reasoning) leads GPT-4o (ChatGPT) by 31.4 points on reasoning.
Top-pick rationale
Grok 4 Fast (Reasoning) wins 7 measurable categories, including Reasoning, Intelligence, GPQA, MMLU Pro.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
GPT-4o (ChatGPT)
OpenAI
TTFT
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Time
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tok/s
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Tokens
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Cost
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Grok 4 Fast (Reasoning)
xAI
TTFT
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Time
—
tok/s
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Tokens
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Cost
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Which answer was more useful?
Full Comparison
| Metric | Op GPT-4o (ChatGPT) | Top Pick xA Grok 4 Fast (Reasoning) |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.00/1M | $0.20/1M |
| Output Cost | $0.00/1M | $0.50/1M |
| Blended (3:1) | — | $0.28/1M |
| Specifications | ||
| Organization | OpenAI | xAI |
| Release Date | Feb 15, 2025 | Sep 19, 2025 |
| Performance & Speed | ||
| Throughput | — | — |
| TTFT | — | — |
| Latency | — | — |
| Composite Indices | ||
| Value Score | — | 100.0 |
| Reasoning Score | 31.8 | 63.2 |
| Intelligence | 14.1 | 35.1 |
| Coding | — | 27.4 |
| Math | — | 89.7 |
| Standard Benchmarks | ||
| GPQA | 51.1% | 84.7% |
| MMLU Pro | 77.3% | 85.0% |
| HLE | 3.7% | 17.0% |
| LiveCodeBench | — | 83.2% |
| MATH 500 | 79.7% | — |
| AIME 2025 | — | 89.7% |
| AIME (Original) | 10.3% | — |
| SciCode | 33.4% | 44.2% |
| LCR | 53.0% | 64.7% |
| IFBench | — | 50.5% |
| TAU-bench v2 | — | 65.8% |
| TerminalBench Hard | — | 18.9% |
Key Takeaways
GPT-4o (ChatGPT) offers the best value at $0.00/1M, 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
GPT-4o (ChatGPT)
- Cost-sensitive applications
- High-volume processing
Grok 4 Fast (Reasoning)
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
