# GPT-5.3 Codex vs Phi 3 Medium 4k Instruct

> GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 33.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-codex-vs-phi-3-medium-4k-instruct
- Last updated: 2026-10-12
- Shared benchmarks: 0

## Summary

- The widest gap is in coding, where GPT-5.3 Codex leads 48.6 to 32.9.
- Phi 3 Medium 4k Instruct has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| Provider | OpenAI | Microsoft |
| Noometry Index | 45.8 | 33.0 |
| Rank | 69 | 250 |
| Context | 400K | — |
| Input $/M | $1.75 | — |
| Output $/M | $14 | — |
| Weights | Proprietary | Open |

## Coding

- GPT-5.3 Codex: 48.6 (#56)
- Phi 3 Medium 4k Instruct: 32.9 (#268)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| SWE-bench Verified | 74.8% | — |
| LMArena WebDev | 1409 | — |
| WeirdML | 79.3% | — |
| LMArena Coding | — | 1130 |
| ALE-Bench | 1,655 | — |

## Agentic & Tool Use

- GPT-5.3 Codex: 48.0 (#9)
- Phi 3 Medium 4k Instruct: —

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |

## Reasoning

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 21.7 (#214)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Hard Prompts | — | 1127 |
| Epoch Capabilities Index | 156.77 | — |

## Math

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 33.4 (#202)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Math | — | 1173 |

## Knowledge

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 30.2 (#229)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Expert | — | 1108 |

## Multilingual

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 30.6 (#263)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Non-English | — | 1094 |
| LMArena Chinese | — | 1108 |
| LMArena French | — | 1110 |
| LMArena German | — | 1101 |
| LMArena Japanese | — | 1042 |
| LMArena Korean | — | 954 |
| LMArena Russian | — | 1145 |
| LMArena Spanish | — | 1095 |

## Instruction Following

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 57.6 (#268)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Instruction Following | — | 1113 |

## Long Context

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 34.0 (#255)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Longer Query | — | 1120 |

## Writing & Preference

- GPT-5.3 Codex: —
- Phi 3 Medium 4k Instruct: 34.1 (#272)

| Benchmark | GPT-5.3 Codex | Phi 3 Medium 4k Instruct |
|---|---|---|
| LMArena Text | — | 1138 |
| LMArena Creative Writing | — | 1107 |
| LMArena Multi-Turn | — | 1088 |

## FAQ

### Is GPT-5.3 Codex better than Phi 3 Medium 4k Instruct?

GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 33.0 on the Noometry Index.

### Is GPT-5.3 Codex or Phi 3 Medium 4k Instruct better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 32.9 in the Noometry coding category.

### How many benchmarks do GPT-5.3 Codex and Phi 3 Medium 4k Instruct share?

0 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Phi 3 Medium 4k Instruct has 17.