# Claude Sonnet 5.5 vs GPT-5-Codex

> Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 37.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-5-vs-gpt-5-codex
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- The widest gap is in coding, where Claude Sonnet 5.5 leads 67.3 to 42.4.
- GPT-5-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 400K.

## Snapshot

| | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 37.9 |
| Rank | 10 | 192 |
| Context | 1M | 400K |
| Input $/M | $2 | $1.25 |
| Output $/M | $10 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Sonnet 5.5: 67.3 (#6)
- GPT-5-Codex: 42.4 (#103)

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1774 | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| WeirdML | — | 54.5% |
| LMArena Coding | 1513 | — |
| ALE-Bench | 1,819 | — |

## Agentic & Tool Use

- Claude Sonnet 5.5: 45.0 (#16)
- GPT-5-Codex: 31.0 (#72)

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |
| APEX-Agents | 75.5% | — |

## Reasoning

- Claude Sonnet 5.5: 54.0 (#28)
- GPT-5-Codex: 30.9 (#83)

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | — | 70.3% |
| NYT Connections (extended) | 80.5% | — |
| CritPt | 31.4% | — |
| LMArena Hard Prompts | 1495 | — |
| Mystery Game Puzzles | 65% | — |
| Epoch Capabilities Index | 165.03 | — |

## Math

- Claude Sonnet 5.5: 87.9 (#6)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| LMArena Math | 1510 | — |
| FrontierMath Erdős | 2.9% | — |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#12)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| GPQA Diamond | 95.6% | — |
| SimpleQA Verified | 46.5% | — |
| LMArena Expert | 1540 | — |

## Multimodal

- Claude Sonnet 5.5: 51.5 (#6)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| LMArena Vision | 1289 | — |
| Furniture Assembly | 75% | — |

## Multilingual

- Claude Sonnet 5.5: 55.3 (#30)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1452 | — |
| LMArena Chinese | 1522 | — |
| LMArena Russian | 1451 | — |

## Instruction Following

- Claude Sonnet 5.5: 78.3 (#11)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1495 | — |

## Long Context

- Claude Sonnet 5.5: 45.9 (#28)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1498 | — |

## Writing & Preference

- Claude Sonnet 5.5: 66.0 (#40)
- GPT-5-Codex: —

| Benchmark | Claude Sonnet 5.5 | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1471 | — |
| LMArena Creative Writing | 1465 | — |
| LMArena Multi-Turn | 1474 | — |

## FAQ

### Is Claude Sonnet 5.5 better than GPT-5-Codex?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 37.9 on the Noometry Index.

### Which is cheaper, Claude Sonnet 5.5 or GPT-5-Codex?

GPT-5-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.

### Is Claude Sonnet 5.5 or GPT-5-Codex better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 42.4 in the Noometry coding category.

### Which has the bigger context window?

Claude Sonnet 5.5 does, with 1M tokens against 400K.

### How many benchmarks do Claude Sonnet 5.5 and GPT-5-Codex share?

0 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-5-Codex has 3.