# Claude 3 Sonnet vs GPT-5.3 Codex

> GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 28.8 on the Noometry Index.

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

## Summary

- They share 2 benchmarks with published results for both. Claude 3 Sonnet scores higher in 0 categories and GPT-5.3 Codex in 1 category; one gap is clear of the uncertainty.
- The widest gap is in coding, where GPT-5.3 Codex leads 48.5 to 29.2.
- The biggest single-benchmark swing is WeirdML: 10.2% for Claude 3 Sonnet and 79.3% for GPT-5.3 Codex.

## Snapshot

| | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 28.8 | 45.5 |
| Rank | 311 | 61 |
| Context | — | 400K |
| Input $/M | — | $1.75 |
| Output $/M | — | $14 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude 3 Sonnet: 29.2 (#296)
- GPT-5.3 Codex: 48.5 (#51)

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| WeirdML | 10.2% | 79.3% |
| SWE-bench Verified | — | 74.8% |
| LMArena WebDev | — | 1408 |
| BigCodeBench Instruct | 42.7% | — |
| LMArena Coding | 1223 | — |
| BigCodeBench Complete | 53.8% | — |
| ALE-Bench | — | 1,655 |
| HumanEval+ | 64% | — |
| MBPP+ | 69.3% | — |

## Agentic & Tool Use

- Claude 3 Sonnet: —
- GPT-5.3 Codex: 47.8 (#9)

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Terminal-Bench | — | 78.4% |
| METR Time Horizons | — | 74.5% |
| Vending-Bench 2 | — | 5,940 |

## Reasoning

- Claude 3 Sonnet: 19.7 (#232)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Epoch Capabilities Index | 120.69 | 156.84 |
| LMArena Hard Prompts | 1197 | — |
| DTBench | 53.6% | — |
| WinoGrande | 75.1% | — |

## Math

- Claude 3 Sonnet: 10.0 (#305)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 2.5% | — |
| LMArena Math | 1213 | — |
| MATH Level 5 | 18.2% | — |

## Knowledge

- Claude 3 Sonnet: 21.1 (#271)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| GPQA Diamond | 40.6% | — |
| LMArena Expert | 1173 | — |
| MMLU | 75.9% | — |

## Multimodal

- Claude 3 Sonnet: 24.7 (#120)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Vision | 984 | — |

## Multilingual

- Claude 3 Sonnet: 38.0 (#229)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Non-English | 1205 | — |
| LMArena Chinese | 1188 | — |
| LMArena French | 1228 | — |
| LMArena German | 1204 | — |
| LMArena Japanese | 1131 | — |
| LMArena Korean | 1128 | — |
| LMArena Russian | 1227 | — |
| LMArena Spanish | 1204 | — |

## Instruction Following

- Claude 3 Sonnet: 63.1 (#230)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Instruction Following | 1200 | — |

## Long Context

- Claude 3 Sonnet: 36.7 (#223)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Longer Query | 1211 | — |

## Writing & Preference

- Claude 3 Sonnet: 42.3 (#233)
- GPT-5.3 Codex: —

| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Text | 1218 | — |
| LMArena Creative Writing | 1186 | — |
| LMArena Multi-Turn | 1227 | — |

## FAQ

### Is Claude 3 Sonnet better than GPT-5.3 Codex?

GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 28.8 on the Noometry Index.

### Is Claude 3 Sonnet or GPT-5.3 Codex better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.5 versus 29.2 in the Noometry coding category.

### How many benchmarks do Claude 3 Sonnet and GPT-5.3 Codex share?

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