Grok 4.5 vs GPT-5.3 Codex
Detailed comparison of API pricing, technical specifications, and benchmark scores. Updated 2026-07-09.
Cost at a Glance
GPT-5.3 Codex is 1.9× more expensive than Grok 4.5 (48.2% savings if you switch).
At 5M input + 2M output tokens per month:
Choosing Grok 4.5 could save you $20.50/mo
Price Comparison (per 1M tokens)
| Metric | Grok 4.5 | GPT-5.3 Codex |
|---|---|---|
| Input (per 1M tokens) | $2.00 | $2.50 |
| Output (per 1M tokens) | $6.00 | $15.00 |
| Cache Write (per 1M tokens) | — | $3.13 |
| Cache Read (per 1M tokens) | $0.50 | $0.25 |
| Batch Input (per 1M tokens) | — | $1.25 |
| Batch Output (per 1M tokens) | — | $7.50 |
Prices are per 1 million tokens. Actual costs depend on your monthly token volume. Use the calculator →
Specifications
| Spec | Grok 4.5 | GPT-5.3 Codex |
|---|---|---|
| Context Window | 500K | 1M |
| Max Output Tokens | 128K | 128K |
| Knowledge Cutoff | 2026-05 | 2025-10 |
| Modalities | Text, Image, Video | Text |
| Prompt Caching | Yes | Yes |
| Batch API | No | Yes |
| Thinking / Reasoning | Yes | No |
Benchmark Scores
| Benchmark | Grok 4.5 | GPT-5.3 Codex |
|---|---|---|
| SWE-bench Verified | 80.0 | 82.0 |
| MMLU-Pro | 84.0 | 83.0 |
| HumanEval | 92.0 | 94.5 |
Benchmark scores from official provider reports. Higher is better. Missing scores indicate the provider has not published that benchmark yet.
Use Cases
Grok 4.5
GPT-5.3 Codex
About the Providers
Grok 4.5 is developed by SpaceXAI. GPT-5.3 Codex is developed by OpenAI. This is a cross-provider comparison between SpaceXAI and OpenAI models. For the most up-to-date pricing, always check the official API documentation from each provider.