Model Comparison
GPT-5.3 Codex (xhigh)
vs. Grok Code Fast 1
Comparing 2 AI models · 10 benchmarks · OpenAI, xAI
Recommended Pick
Op GPT-5.3 Codex (xhigh) 11 metric wins Strongest on: Throughput, Reasoning, Intelligence
Lowest Price
Grok Code Fast 1
$0.00/1M input price
Best Reasoning
GPT-5.3 Codex (xhigh)
61.7 reasoning score
Blends available reasoning benchmarks
Best for Coding
GPT-5.3 Codex (xhigh)
53.1 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
Grok Code Fast 1 is ∞x cheaper on input tokens than GPT-5.3 Codex (xhigh).
Reasoning gap
GPT-5.3 Codex (xhigh) leads Grok Code Fast 1 by 22.6 points on reasoning.
Coding gap
GPT-5.3 Codex (xhigh) leads Grok Code Fast 1 by 29.4 points on coding.
Top-pick rationale
GPT-5.3 Codex (xhigh) wins 11 measurable categories, including Throughput, Reasoning, Intelligence, Coding.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
GPT-5.3 Codex (xhigh)
OpenAI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Grok Code Fast 1
xAI
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Which answer was more useful?
Full Comparison
| Metric | Top Pick Op GPT-5.3 Codex (xhigh) | xA Grok Code Fast 1 |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $1.75/1M | $0.00/1M |
| Output Cost | $14.00/1M | $0.00/1M |
| Blended (3:1) | $4.81/1M | — |
| Specifications | ||
| Organization | OpenAI | xAI |
| Release Date | Feb 5, 2026 | Aug 28, 2025 |
| Performance & Speed | ||
| Throughput | 99.1 tok/s | — |
| TTFT | 60437ms | — |
| Latency | 60437ms | — |
| Composite Indices | ||
| Value Score | 100.0 | — |
| Reasoning Score | 61.7 | 39.1 |
| Intelligence | 53.6 | 28.7 |
| Coding | 53.1 | 23.7 |
| Math | — | 43.3 |
| Standard Benchmarks | ||
| GPQA | 91.5% | 72.7% |
| MMLU Pro | — | 79.3% |
| HLE | 39.9% | 7.5% |
| LiveCodeBench | — | 65.7% |
| AIME 2025 | — | 43.3% |
| SciCode | 53.2% | 36.2% |
| LCR | 74.0% | 48.3% |
| IFBench | 75.4% | 41.4% |
| TAU-bench v2 | 86.0% | 75.7% |
| TerminalBench Hard | 53.0% | 17.4% |
Key Takeaways
Grok Code Fast 1 offers the best value at $0.00/1M, making it ideal for high-volume applications and cost-conscious projects.
GPT-5.3 Codex (xhigh) has the strongest reasoning profile with a 61.7 reasoning score, combining the available reasoning-heavy benchmarks.
GPT-5.3 Codex (xhigh) reaches a 53.1 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-5.3 Codex (xhigh)
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
Grok Code Fast 1
- Cost-sensitive applications
- High-volume processing
