Key Takeaways
GPT-5.3 Codex wins:
- Larger context window
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Supports vision
- Has reasoning mode
Llama 3.1 405B Instruct wins:
- Cheaper input tokens
- Cheaper output tokens
- Better at math
Price Advantage
Llama 3.1 405B Instruct
Benchmark Advantage
GPT-5.3 Codex
Context Window
GPT-5.3 Codex
Speed
GPT-5.3 Codex
Pricing Comparison
Price Comparison
| Metric | GPT-5.3 Codex | Llama 3.1 405B Instruct | Winner |
|---|---|---|---|
| Input (per 1M tokens) | $1.75 | $0.90 | Llama 3.1 405B Instruct |
| Output (per 1M tokens) | $14.00 | $0.90 | Llama 3.1 405B Instruct |
| Cache Read (per 1M) | $0.17 | $0.45 | GPT-5.3 Codex |
Using a 3:1 input/output ratio, Llama 3.1 405B Instruct is 81% cheaper overall.
GPT-5.3 Codex Providers
No provider data available
Llama 3.1 405B Instruct Providers
No provider data available
Benchmark Comparison
8
Benchmarks Compared
3
GPT-5.3 Codex Wins
0
Llama 3.1 405B Instruct Wins
Benchmark Scores
| Benchmark | GPT-5.3 Codex | Llama 3.1 405B Instruct | Winner |
|---|---|---|---|
Intelligence Index Overall intelligence score | 54.0 | 17.4 | |
Coding Index Code generation & understanding | 53.1 | 14.5 | |
Math Index Mathematical reasoning | - | 3.0 | - |
MMLU Pro Academic knowledge | - | 73.2 | - |
GPQA Graduate-level science | 91.5 | 51.5 | |
LiveCodeBench Competitive programming | - | 30.5 | - |
Aider Real-world code editing | - | 66.2 | - |
AIME Competition math | - | 21.3 | - |
GPT-5.3 Codex significantly outperforms in coding benchmarks.
Cost vs Quality
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Other models
Context & Performance
Context Window
GPT-5.3 Codex
400,000
tokens
Llama 3.1 405B Instruct
131,000
tokens
GPT-5.3 Codex has a 67% larger context window.
Speed Performance
| Metric | GPT-5.3 Codex | Llama 3.1 405B Instruct | Winner |
|---|---|---|---|
| Tokens/second | 68.4 tok/s | 33.7 tok/s | |
| Time to First Token | 87.36s | 0.71s |
GPT-5.3 Codex responds 103% faster on average.
Capabilities
Feature Comparison
| Feature | GPT-5.3 Codex | Llama 3.1 405B Instruct |
|---|---|---|
| Vision (Image Input) | ||
| Tool/Function Calls | ||
| Reasoning Mode | ||
| Audio Input | ||
| Audio Output | ||
| PDF Input | ||
| Prompt Caching | ||
| Web Search |
License & Release
| Property | GPT-5.3 Codex | Llama 3.1 405B Instruct |
|---|---|---|
| License | Proprietary | Open Source |
| Author | OpenAI | Meta-llama |
| Released | Feb 2026 | Jul 2024 |
GPT-5.3 Codex Modalities
Input
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Output
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Llama 3.1 405B Instruct Modalities
Input
text
Output
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