Updated March 26, 2026· Based on independent benchmark data
GPT-5.1 (high) leads in intelligence with a score of 47.7 vs 44.6. For speed, GPT-5 Codex (high) wins at 180 tok/s vs 92 tok/s.
| Metric | GPT-5.1 (high) | GPT-5 Codex (high) |
|---|---|---|
| Intelligence Score | 47.7 | 44.6 |
| Coding Score | 44.7 | 38.9 |
| Math Score | 94.0 | 98.7 |
| Speed (tok/s) | 92 tok/s | 180 tok/s |
| Latency (TTFT) | 39.04s | 9.17s |
| Input Price / 1M tokens | $1.25 | $1.25 |
| Output Price / 1M tokens | $10 | $10 |
| Context Window | N/A | N/A |
GPT-5.1 (high) outperforms GPT-5 Codex (high) on the intelligence index with a score of 47.7 compared to 44.6. For coding tasks, GPT-5.1 (high) has the edge with a coding score of 44.7 vs 38.9. In mathematical reasoning, GPT-5 Codex (high) leads with 98.7 compared to GPT-5.1 (high)'s 94.0.
GPT-5 Codex (high) generates output significantly faster at 180 tok/s compared to GPT-5.1 (high)'s 92 tok/s, making it 2.0x faster for streaming responses. Time to first token is 9.17s for GPT-5 Codex (high) vs 39.04s for GPT-5.1 (high), which affects perceived responsiveness in interactive applications.
GPT-5 Codex (high) is more affordable at $1.25/1M input tokens ($10/1M output), while GPT-5.1 (high) costs $1.25/1M input ($10/1M output). For a typical workload of 100 requests per day at 2,000 tokens each, GPT-5.1 (high) would cost approximately $7.50/month vs $7.50/month for GPT-5 Codex (high) in input costs alone.
Choose GPT-5.1 (high) when you need higher intelligence (47.7), stronger coding performance (44.7). Choose GPT-5 Codex (high) when you need faster output (180 tok/s).
GPT-5.1 (high) scores higher on coding benchmarks (44.7 vs 38.9), making it the better choice for programming tasks.
GPT-5 Codex (high) is cheaper at $1.25/1M input tokens vs $1.25/1M for GPT-5.1 (high).
GPT-5 Codex (high) is faster, producing output at 180 tok/s compared to GPT-5.1 (high)'s 92 tok/s.
No, GPT-5.1 (high) does not support image input. Neither model supports image input.
Data last synced: March 26, 2026
| Max Output Tokens | N/A | N/A |
| Input Modalities | Text | Text |
| Output Modalities | Text | Text |
| Free Tier | No | No |
It depends on your priorities. GPT-5.1 (high) scores higher on intelligence (47.7), but GPT-5 Codex (high) may be better for specific use cases like budget-conscious projects or speed-critical applications.