# Claude Sonnet 5.5 vs GPT-5.3 Chat

> Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 42.8 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-5-vs-gpt-5-3-chat
- Last updated: 2026-10-10
- Shared benchmarks: 12

## Summary

- They share 12 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 8 categories and GPT-5.3 Chat in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 38.2.
- Claude Sonnet 5.5 is cheaper at $2 / $10 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 128K.

## Snapshot

| | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 42.8 |
| Rank | 10 | 109 |
| Context | 1M | 128K |
| Input $/M | $2 | $1.75 |
| Output $/M | $10 | $14 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Sonnet 5.5: 67.3 (#6)
- GPT-5.3 Chat: 41.4 (#124)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Coding | 1513 | 1408 |
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1774 | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| ALE-Bench | 1,819 | — |

## Agentic & Tool Use

- Claude Sonnet 5.5: 45.0 (#16)
- GPT-5.3 Chat: —

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| APEX-Agents | 75.5% | — |

## Reasoning

- Claude Sonnet 5.5: 54.0 (#28)
- GPT-5.3 Chat: 28.5 (#102)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Hard Prompts | 1495 | 1399 |
| NYT Connections (extended) | 80.5% | — |
| CritPt | 31.4% | — |
| Mystery Game Puzzles | 65% | — |
| Epoch Capabilities Index | 165.03 | — |

## Math

- Claude Sonnet 5.5: 87.9 (#6)
- GPT-5.3 Chat: 38.2 (#142)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Math | 1510 | 1389 |
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| FrontierMath Erdős | 2.9% | — |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#12)
- GPT-5.3 Chat: 38.8 (#140)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Expert | 1540 | 1397 |
| GPQA Diamond | 95.6% | — |
| SimpleQA Verified | 46.5% | — |

## Multimodal

- Claude Sonnet 5.5: 51.5 (#6)
- GPT-5.3 Chat: —

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Vision | 1289 | — |
| Furniture Assembly | 75% | — |

## Multilingual

- Claude Sonnet 5.5: 55.3 (#30)
- GPT-5.3 Chat: 50.3 (#124)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Non-English | 1452 | 1382 |
| LMArena Chinese | 1522 | 1432 |
| LMArena Russian | 1451 | 1400 |
| LMArena French | — | 1397 |
| LMArena German | — | 1384 |
| LMArena Japanese | — | 1352 |
| LMArena Korean | — | 1346 |
| LMArena Spanish | — | 1371 |

## Instruction Following

- Claude Sonnet 5.5: 78.3 (#11)
- GPT-5.3 Chat: 72.8 (#129)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Instruction Following | 1495 | 1378 |

## Long Context

- Claude Sonnet 5.5: 45.9 (#28)
- GPT-5.3 Chat: 42.6 (#120)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Longer Query | 1498 | 1396 |

## Writing & Preference

- Claude Sonnet 5.5: 66.0 (#40)
- GPT-5.3 Chat: 63.1 (#68)

| Benchmark | Claude Sonnet 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Text | 1471 | 1389 |
| LMArena Creative Writing | 1465 | 1355 |
| LMArena Multi-Turn | 1474 | 1412 |
| EQ-Bench Creative Writing | — | 1690 |

## FAQ

### Is Claude Sonnet 5.5 better than GPT-5.3 Chat?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 42.8 on the Noometry Index.

### Which is cheaper, Claude Sonnet 5.5 or GPT-5.3 Chat?

Claude Sonnet 5.5 is cheaper. It lists at $2 per million input tokens and $10 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

### Is Claude Sonnet 5.5 or GPT-5.3 Chat better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 41.4 in the Noometry coding category.

### Which has the bigger context window?

Claude Sonnet 5.5 does, with 1M tokens against 128K.

### How many benchmarks do Claude Sonnet 5.5 and GPT-5.3 Chat share?

12 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-5.3 Chat has 18.