GPT-5.3-Codex vs Grok-4 Heavy
OpenAI vs xAI — benchmarks, pricing, and capabilities side by side.
- •GPT-5.3-Codex has the higher intelligence index (91.5 vs 89.3)
| GPT-5.3-Codex | Grok-4 Heavy | |
|---|---|---|
| Intelligence index | 91.5 | 89.3 |
| Developer | OpenAI | xAI |
| Type | Multimodal | Multimodal |
| Access | API only | API only |
| Context window | 400,000 tokens | — |
| Input price | $1.75 / 1M | — |
| Output price | $14.00 / 1M | — |
| Speed | 73 tok/s | — |
| Released | February 24, 2026 | July 9, 2025 |
| Parameters | — | — |
| Input modalities | Text, Image | — |
| Output modalities | Text | — |
Shared benchmarks
GPT-5.3-Codex
Grok-4 Heavy
GPQA Diamond
91.5
88.4
Humanity’s Last Exam
39.9
50.7