Key Takeaways
GPT-5 Codex wins:
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Better at math
GPT-5.1-Codex wins:
- No clear advantages in compared metrics
Price Advantage
GPT-5 Codex
Benchmark Advantage
GPT-5 Codex
Context Window
GPT-5.1-Codex
Speed
GPT-5 Codex
Pricing Comparison
Price Comparison
| Metric | GPT-5 Codex | GPT-5.1-Codex | Winner |
|---|---|---|---|
| Input (per 1M tokens) | $1.25 | $1.25 | Tie |
| Output (per 1M tokens) | $10.00 | $10.00 | Tie |
| Cache Read (per 1M) | $125000.00 | $125000.00 | Tie |
Both models have similar overall pricing.
GPT-5 Codex Providers
OpenAI $1.25 (Cheapest)
GPT-5.1-Codex Providers
OpenAI $1.25 (Cheapest)
Azure $1.25 (Cheapest)
Benchmark Comparison
6
Benchmarks Compared
4
GPT-5 Codex Wins
2
GPT-5.1-Codex Wins
Benchmark Scores
| Benchmark | GPT-5 Codex | GPT-5.1-Codex | Winner |
|---|---|---|---|
Intelligence Index Overall intelligence score | 44.5 | 42.2 | |
Coding Index Code generation & understanding | 38.9 | 36.6 | |
Math Index Mathematical reasoning | 98.7 | 95.7 | |
MMLU Pro Academic knowledge | 86.5 | 86.0 | |
GPQA Graduate-level science | 83.7 | 86.0 | |
LiveCodeBench Competitive programming | 84.0 | 84.9 |
GPT-5 Codex wins 4 out of 6 benchmarks.
Cost vs Quality
X-axis:
Y-axis:
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GPT-5 Codex
Other models
Context & Performance
Context Window
GPT-5 Codex
400,000
tokens
Max output: 128,000 tokens
GPT-5.1-Codex
400,000
tokens
Max output: 128,000 tokens
Speed Performance
| Metric | GPT-5 Codex | GPT-5.1-Codex | Winner |
|---|---|---|---|
| Tokens/second | 338.6 tok/s | 219.1 tok/s | |
| Time to First Token | 14.88s | 12.40s |
GPT-5 Codex responds 55% faster on average.
Capabilities
Feature Comparison
| Feature | GPT-5 Codex | GPT-5.1-Codex |
|---|---|---|
| Vision (Image Input) | ||
| Tool/Function Calls | ||
| Reasoning Mode | ||
| Audio Input | ||
| Audio Output | ||
| PDF Input | ||
| Prompt Caching | ||
| Web Search |
License & Release
| Property | GPT-5 Codex | GPT-5.1-Codex |
|---|---|---|
| License | Proprietary | Proprietary |
| Author | OpenAI | OpenAI |
| Released | Sep 2025 | Nov 2025 |
GPT-5 Codex Modalities
Input
textimage
Output
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GPT-5.1-Codex Modalities
Input
textimage
Output
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