# GPT-5.3 Codex vs Nemotron 3 Ultra

> GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 42.5 on the Noometry Index. Nemotron 3 Ultra costs 4.6× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-3-codex-vs-nemotron-3-ultra
- Last updated: 2026-10-12
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. GPT-5.3 Codex scores higher in 2 categories and Nemotron 3 Ultra in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where GPT-5.3 Codex leads 48.0 to 23.4.
- The biggest single-benchmark swing is WeirdML: 79.3% for GPT-5.3 Codex and 43.5% for Nemotron 3 Ultra.
- Nemotron 3 Ultra is cheaper at $0.60 / $2.40 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
- GPT-5.3 Codex accepts more context: 400K tokens versus 262K.
- Nemotron 3 Ultra has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| Provider | OpenAI | NVIDIA |
| Noometry Index | 45.8 | 42.5 |
| Rank | 69 | 113 |
| Context | 400K | 262K |
| Input $/M | $1.75 | $0.60 |
| Output $/M | $14 | $2.40 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.3 Codex: 48.6 (#56)
- Nemotron 3 Ultra: 38.1 (#182)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| WeirdML | 79.3% | 43.5% |
| SWE-bench Verified | 74.8% | — |
| FrontierCode | — | 13.6% |
| LMArena WebDev | 1409 | — |
| SciCode | — | 40.3% |
| LMArena Coding | — | 1468 |
| ALE-Bench | 1,655 | — |

## Agentic & Tool Use

- GPT-5.3 Codex: 48.0 (#9)
- Nemotron 3 Ultra: 23.4 (#126)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| APEX-Agents | — | 22.7% |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |

## Reasoning

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 31.0 (#82)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| Epoch Capabilities Index | 156.77 | 146.17 |
| CritPt | — | 3.1% |
| Chess Puzzles | — | 12% |
| LMArena Hard Prompts | — | 1452 |
| Mystery Game Puzzles | — | 20% |
| DTBench | — | 90.1% |
| LMCA | — | 36.9% |

## Math

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 35.3 (#187)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| OTIS Mock AIME 2024-2025 | — | 86.7% |
| ProofBench | — | 2% |
| LMArena Math | — | 1457 |

## Knowledge

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 52.5 (#61)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| GPQA Diamond | — | 85.4% |
| LMArena Expert | — | 1472 |

## Multilingual

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 53.5 (#64)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| LMArena Non-English | — | 1427 |
| LMArena Chinese | — | 1497 |
| LMArena French | — | 1472 |
| LMArena German | — | 1471 |
| LMArena Korean | — | 1386 |
| LMArena Russian | — | 1417 |
| LMArena Spanish | — | 1454 |

## Instruction Following

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 74.7 (#88)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| LMArena Instruction Following | — | 1418 |

## Long Context

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 43.9 (#81)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| LMArena Longer Query | — | 1437 |

## Writing & Preference

- GPT-5.3 Codex: —
- Nemotron 3 Ultra: 66.3 (#36)

| Benchmark | GPT-5.3 Codex | Nemotron 3 Ultra |
|---|---|---|
| LMArena Text | — | 1445 |
| LMArena Creative Writing | — | 1398 |
| EQ-Bench Creative Writing | — | 1692 |
| LMArena Multi-Turn | — | 1411 |

## FAQ

### Is GPT-5.3 Codex better than Nemotron 3 Ultra?

GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 42.5 on the Noometry Index. Nemotron 3 Ultra costs 4.6× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.

### Which is cheaper, GPT-5.3 Codex or Nemotron 3 Ultra?

Nemotron 3 Ultra is cheaper. It lists at $0.60 per million input tokens and $2.40 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.

### Is GPT-5.3 Codex or Nemotron 3 Ultra better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 38.1 in the Noometry coding category.

### Which has the bigger context window?

GPT-5.3 Codex does, with 400K tokens against 262K.

### How many benchmarks do GPT-5.3 Codex and Nemotron 3 Ultra share?

2 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Nemotron 3 Ultra has 30.