# GPT-5.3 Chat vs Mercury

> GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 37.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-chat-vs-mercury
- Last updated: 2026-10-10
- Shared benchmarks: 8

## Summary

- They share 8 benchmarks with published results for both. GPT-5.3 Chat scores higher in 6 categories and Mercury in 0 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where GPT-5.3 Chat leads 63.1 to 46.2.

## Snapshot

| | GPT-5.3 Chat | Mercury |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 42.8 | 37.6 |
| Rank | 109 | 199 |
| Context | 128K | — |
| Input $/M | $1.75 | — |
| Output $/M | $14 | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Chat: 41.4 (#124)
- Mercury: 38.7 (#170)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Coding | 1408 | 1322 |

## Reasoning

- GPT-5.3 Chat: 28.5 (#102)
- Mercury: 17.5 (#293)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1285 |
| Kagi LLM Benchmark | — | 21.6% |

## Math

- GPT-5.3 Chat: 38.2 (#142)
- Mercury: —

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Math | 1389 | — |

## Knowledge

- GPT-5.3 Chat: 38.8 (#140)
- Mercury: —

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Expert | 1397 | — |

## Multilingual

- GPT-5.3 Chat: 50.3 (#124)
- Mercury: 41.6 (#206)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Non-English | 1382 | 1260 |
| LMArena Chinese | 1432 | — |
| LMArena French | 1397 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1346 | — |
| LMArena Russian | 1400 | — |
| LMArena Spanish | 1371 | — |

## Instruction Following

- GPT-5.3 Chat: 72.8 (#129)
- Mercury: 65.2 (#224)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Instruction Following | 1378 | 1239 |

## Long Context

- GPT-5.3 Chat: 42.6 (#120)
- Mercury: 38.4 (#198)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Longer Query | 1396 | 1266 |

## Writing & Preference

- GPT-5.3 Chat: 63.1 (#68)
- Mercury: 46.2 (#221)

| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Text | 1389 | 1282 |
| LMArena Creative Writing | 1355 | 1191 |
| LMArena Multi-Turn | 1412 | 1282 |
| EQ-Bench Creative Writing | 1690 | — |

## FAQ

### Is GPT-5.3 Chat better than Mercury?

GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 37.6 on the Noometry Index.

### Is GPT-5.3 Chat or Mercury better for coding?

GPT-5.3 Chat scores higher on coding benchmarks: 41.4 versus 38.7 in the Noometry coding category.

### How many benchmarks do GPT-5.3 Chat and Mercury share?

8 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Mercury has 9.