# GPT-5.3 Codex vs Phi-3.5-mini

> Side-by-side benchmark comparison for GPT-5.3 Codex and Phi-3.5-mini across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-3-codex-vs-phi-3-5-mini
- Last updated: October 14, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for GPT-5.3 Codex and Phi-3.5-mini.

## Summary

- GPT-5.3 Codex and Phi-3.5-mini do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | GPT-5.3 Codex | Phi-3.5-mini |
|----------|----------|----------|
| Creator | OpenAI | Microsoft |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 400K | 128K |
| Independent public score (not head-to-head) | 59.84 | null |
| Benchmarks Covered | 11 | 8 |
| Pricing (input/output) | $1.75 / $14.00 | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 55.2 (Estimated · #35/124)
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 77.3% | Coming soon | Coming soon |
| OSWorld-Verified | 64.7% | Coming soon | Coming soon |
| Gert Labs | 57.47% | Coming soon | Coming soon |
| JobBench | 33.7% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 54.5 (Supported · #31/149)
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85% | Coming soon | Coming soon |
| SWE-bench Pro | 56.8% | Coming soon | Coming soon |
| SWE-Rebench | 58.2% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | 77.3% | Coming soon | Coming soon |
| Vibe Code Bench | 61.77% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 87.3% | Coming soon | Coming soon |
| SWE-bench (Vals) | 78.0% | Coming soon | Coming soon |
| HumanEval | Coming soon | 62.8% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 83.1 (Unranked · 2 rankable rows)
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| BBH | Coming soon | 69% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 80.1 (Unranked · 1 rankable row)
- Phi-3.5-mini public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 65.3 (Estimated · #31/181)
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| MMLU | Coming soon | 69% | Coming soon |
| MMLU-Pro | Coming soon | 47.4% | Coming soon |
| GPQA | Coming soon | 30.4% | Coming soon |
| MMMLU | Coming soon | 55.4% | Coming soon |

### Multilingual

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: Coming soon
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| MGSM | Coming soon | 47.9% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 92.6 (#18/128)
- Phi-3.5-mini public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: Coming soon
- Phi-3.5-mini public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Phi-3.5-mini | Winner |
|-----------|-----------|-----------|--------|
| GSM8K | Coming soon | 86.2% | Coming soon |

## FAQ

### Can I compare GPT-5.3 Codex and Phi-3.5-mini on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [GPT-5.3 Codex vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-vs-gpt-5-3-codex-spark)
- [Phi-3.5-mini vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-spark-vs-phi-3-5-mini)
- [GPT-5.3 Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-3-codex)
- [Phi-3.5-mini vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-phi-3-5-mini)

## Explore More

- [GPT-5.3 Codex profile](/models/gpt-5-3-codex)
- [Phi-3.5-mini profile](/models/phi-3-5-mini)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)