Key Takeaways
GPT-5.3 Codex wins:
- Larger context window
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Supports vision
- Has reasoning mode
Phi-3 Medium 128K Instruct wins:
- Cheaper input tokens
- Cheaper output tokens
Price Advantage
Phi-3 Medium 128K 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 | Phi-3 Medium 128K Instruct | Winner |
|---|---|---|---|
| Input (per 1M tokens) | $1.75 | $1.00 | Phi-3 Medium 128K Instruct |
| Output (per 1M tokens) | $14.00 | $1.00 | Phi-3 Medium 128K Instruct |
| Cache Read (per 1M) | $0.17 | N/A | GPT-5.3 Codex |
Using a 3:1 input/output ratio, Phi-3 Medium 128K Instruct is 79% cheaper overall.
GPT-5.3 Codex Providers
No provider data available
Phi-3 Medium 128K Instruct Providers
No provider data available
Benchmark Comparison
5
Benchmarks Compared
2
GPT-5.3 Codex Wins
0
Phi-3 Medium 128K Instruct Wins
Benchmark Scores
| Benchmark | GPT-5.3 Codex | Phi-3 Medium 128K Instruct | Winner |
|---|---|---|---|
Intelligence Index Overall intelligence score | 54.0 | 32.0 | |
Coding Index Code generation & understanding | 53.1 | - | - |
MMLU Pro Academic knowledge | - | 41.2 | - |
GPQA Graduate-level science | 91.5 | 11.5 | |
BBH Big-Bench Hard | - | 48.5 | - |
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
Phi-3 Medium 128K Instruct
128,000
tokens
GPT-5.3 Codex has a 68% larger context window.
Speed Performance
| Metric | GPT-5.3 Codex | Phi-3 Medium 128K Instruct | Winner |
|---|---|---|---|
| Tokens/second | 68.4 tok/s | N/A | |
| Time to First Token | 87.36s | N/A |
Capabilities
Feature Comparison
| Feature | GPT-5.3 Codex | Phi-3 Medium 128K 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 | Phi-3 Medium 128K Instruct |
|---|---|---|
| License | Proprietary | Open Source |
| Author | OpenAI | Microsoft |
| Released | Feb 2026 | Unknown |
GPT-5.3 Codex Modalities
Input
textimage
Output
text
Phi-3 Medium 128K Instruct Modalities
Input
Output