Key Takeaways
ChatGPT-4o wins:
- No clear advantages in compared metrics
GPT-5 Codex wins:
- Cheaper input tokens
- Cheaper output tokens
- Larger context window
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Better at math
Price Advantage
GPT-5 Codex
Benchmark Advantage
GPT-5 Codex
Context Window
GPT-5 Codex
Speed
GPT-5 Codex
Pricing Comparison
Price Comparison
| Metric | ChatGPT-4o | GPT-5 Codex | Winner |
|---|---|---|---|
| Input (per 1M tokens) | $5.00 | $1.25 | GPT-5 Codex |
| Output (per 1M tokens) | $15.00 | $10.00 | GPT-5 Codex |
| Cache Read (per 1M) | N/A | $125000.00 | GPT-5 Codex |
Using a 3:1 input/output ratio, GPT-5 Codex is 54% cheaper overall.
ChatGPT-4o Providers
OpenAI $5.00 (Cheapest)
Azure $5.00 (Cheapest)
GPT-5 Codex Providers
OpenAI $1.25 (Cheapest)
Benchmark Comparison
8
Benchmarks Compared
0
ChatGPT-4o Wins
5
GPT-5 Codex Wins
Benchmark Scores
| Benchmark | ChatGPT-4o | GPT-5 Codex | Winner |
|---|---|---|---|
Intelligence Index Overall intelligence score | 18.6 | 44.5 | |
Coding Index Code generation & understanding | - | 38.9 | - |
Math Index Mathematical reasoning | 25.7 | 98.7 | |
MMLU Pro Academic knowledge | 80.3 | 86.5 | |
GPQA Graduate-level science | 65.5 | 83.7 | |
LiveCodeBench Competitive programming | 42.5 | 84.0 | |
Aider Real-world code editing | 72.2 | - | - |
AIME Competition math | 32.7 | - | - |
GPT-5 Codex significantly outperforms in coding benchmarks.
Cost vs Quality
X-axis:
Y-axis:
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ChatGPT-4o
Other models
Context & Performance
Context Window
ChatGPT-4o
128,000
tokens
Max output: 16,384 tokens
GPT-5 Codex
400,000
tokens
Max output: 128,000 tokens
GPT-5 Codex has a 68% larger context window.
Speed Performance
| Metric | ChatGPT-4o | GPT-5 Codex | Winner |
|---|---|---|---|
| Tokens/second | 180.3 tok/s | 314.7 tok/s | |
| Time to First Token | 0.42s | 10.95s |
GPT-5 Codex responds 75% faster on average.
Capabilities
Feature Comparison
| Feature | ChatGPT-4o | GPT-5 Codex |
|---|---|---|
| Vision (Image Input) | ||
| Tool/Function Calls | ||
| Reasoning Mode | ||
| Audio Input | ||
| Audio Output | ||
| PDF Input | ||
| Prompt Caching | ||
| Web Search |
License & Release
| Property | ChatGPT-4o | GPT-5 Codex |
|---|---|---|
| License | Proprietary | Proprietary |
| Author | OpenAI | OpenAI |
| Released | Aug 2024 | Sep 2025 |
ChatGPT-4o Modalities
Input
textimage
Output
text
GPT-5 Codex Modalities
Input
textimage
Output
text