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GPT-5.3 Codex vs o4-mini
A detailed comparison of GPT-5.3 Codex (OpenAI) and o4-mini (OpenAI) across pricing, performance, and features.
Pricing Comparison
| Metric | GPT-5.3 Codex | o4-mini | Difference |
|---|---|---|---|
| Input / 1M tokens | $2.00 | $1.10 | -45% |
| Output / 1M tokens | $16.00 | $4.40 | -73% |
| Context window | 200K | 200K | — |
| Max output | 65.536K | 100K | — |
Benchmark Comparison
| Benchmark | GPT-5.3 Codex | o4-mini |
|---|---|---|
| MMLU-Pro | 90% | 85% |
| HumanEval | 96.5% | 93.5% |
| GPQA | 78% | 76% |
Capabilities
| Capability | GPT-5.3 Codex | o4-mini |
|---|---|---|
| code | ✓ | ✓ |
| reasoning | ✓ | ✓ |
| text | ✓ | ✓ |
| tool-use | ✓ | ✓ |
| vision | ✓ | ✓ |
GPT-5.3 Codex Strengths
- ✓Best coding model from OpenAI
- ✓Large output window (65K tokens)
- ✓Strong reasoning for complex tasks
GPT-5.3 Codex Weaknesses
- ✗API access not yet available
- ✗Premium pricing
o4-mini Strengths
- ✓Affordable reasoning model
- ✓200K context window
- ✓Good for math and science
o4-mini Weaknesses
- ✗Slower than non-reasoning models
- ✗Reasoning tokens add to effective cost
Quick Verdict
Best value: o4-mini is the more affordable option at $1.1/$4.4 per 1M tokens.
Higher benchmarks: GPT-5.3 Codex scores higher on average across available benchmarks (88.2% avg).
Choose o4-mini if cost matters most. Choose GPT-5.3 Codex if you need the best possible quality for complex tasks.