# GPT-5.3 Codex vs Step 2 16k Exp 202412

> GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 38.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-codex-vs-step-2-16k-exp-202412
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- The widest gap is in coding, where GPT-5.3 Codex leads 48.5 to 37.9.

## Snapshot

| | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 45.5 | 38.6 |
| Rank | 61 | 173 |
| Context | 400K | — |
| Input $/M | $1.75 | — |
| Output $/M | $14 | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Codex: 48.5 (#51)
- Step 2 16k Exp 202412: 37.9 (#170)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| SWE-bench Verified | 74.8% | — |
| LMArena WebDev | 1408 | — |
| WeirdML | 79.3% | — |
| LMArena Coding | — | 1316 |
| ALE-Bench | 1,655 | — |

## Agentic & Tool Use

- GPT-5.3 Codex: 47.8 (#9)
- Step 2 16k Exp 202412: —

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |

## Reasoning

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 24.8 (#140)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Hard Prompts | — | 1299 |
| Epoch Capabilities Index | 156.84 | — |

## Math

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 33.6 (#171)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Math | — | 1305 |

## Knowledge

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 34.6 (#187)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Expert | — | 1279 |

## Multilingual

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 43.9 (#176)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Non-English | — | 1290 |
| LMArena Chinese | — | 1331 |
| LMArena Russian | — | 1324 |

## Instruction Following

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 68.1 (#187)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Instruction Following | — | 1287 |

## Long Context

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 39.7 (#165)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Longer Query | — | 1307 |

## Writing & Preference

- GPT-5.3 Codex: —
- Step 2 16k Exp 202412: 52.5 (#168)

| Benchmark | GPT-5.3 Codex | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Text | — | 1321 |
| LMArena Creative Writing | — | 1328 |
| LMArena Multi-Turn | — | 1292 |

## FAQ

### Is GPT-5.3 Codex better than Step 2 16k Exp 202412?

GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 38.6 on the Noometry Index.

### Is GPT-5.3 Codex or Step 2 16k Exp 202412 better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.5 versus 37.9 in the Noometry coding category.

### How many benchmarks do GPT-5.3 Codex and Step 2 16k Exp 202412 share?

0 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Step 2 16k Exp 202412 has 12.