# GPT-5-Codex vs Mercury

> GPT-5-Codex and Mercury score almost the same on the Noometry Index (37.9 vs 37.6), so choose on price, context window or the category you care about most.

- Canonical page: https://noometry.com/compare/gpt-5-codex-vs-mercury
- Last updated: 2026-10-12
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GPT-5-Codex scores higher in 2 categories and Mercury in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5-Codex leads 30.9 to 17.5.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 70.3% for GPT-5-Codex and 21.6% for Mercury.

## Snapshot

| | GPT-5-Codex | Mercury |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 37.9 | 37.6 |
| Rank | 192 | 199 |
| Context | 400K | — |
| Input $/M | $1.25 | — |
| Output $/M | $10 | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5-Codex: 42.4 (#103)
- Mercury: 38.7 (#170)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| WeirdML | 54.5% | — |
| LMArena Coding | — | 1322 |

## Agentic & Tool Use

- GPT-5-Codex: 31.0 (#72)
- Mercury: —

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| Terminal-Bench | 44.3% | — |

## Reasoning

- GPT-5-Codex: 30.9 (#83)
- Mercury: 17.5 (#293)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| Kagi LLM Benchmark | 70.3% | 21.6% |
| LMArena Hard Prompts | — | 1285 |

## Multilingual

- GPT-5-Codex: —
- Mercury: 41.6 (#206)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| LMArena Non-English | — | 1260 |

## Instruction Following

- GPT-5-Codex: —
- Mercury: 65.2 (#224)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| LMArena Instruction Following | — | 1239 |

## Long Context

- GPT-5-Codex: —
- Mercury: 38.4 (#198)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| LMArena Longer Query | — | 1266 |

## Writing & Preference

- GPT-5-Codex: —
- Mercury: 46.2 (#221)

| Benchmark | GPT-5-Codex | Mercury |
|---|---|---|
| LMArena Text | — | 1282 |
| LMArena Creative Writing | — | 1191 |
| LMArena Multi-Turn | — | 1282 |

## FAQ

### Is GPT-5-Codex better than Mercury?

GPT-5-Codex and Mercury score almost the same on the Noometry Index (37.9 vs 37.6), so choose on price, context window or the category you care about most.

### Is GPT-5-Codex or Mercury better for coding?

GPT-5-Codex scores higher on coding benchmarks: 42.4 versus 38.7 in the Noometry coding category.

### How many benchmarks do GPT-5-Codex and Mercury share?

1 benchmark has published results for both models. GPT-5-Codex has 3 scored results on Noometry and Mercury has 9.