# GLM-4.5-Air vs GPT-5-Codex

> GLM-4.5-Air is the stronger model overall, scoring 38.7 to 37.3 on the Noometry Index.

- Canonical page: https://noometry.com/compare/glm-4-5-air-vs-gpt-5-codex
- Last updated: 2026-10-10
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GLM-4.5-Air scores higher in 0 categories and GPT-5-Codex in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in coding, where GPT-5-Codex leads 41.9 to 34.5.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 43% for GLM-4.5-Air and 70.3% for GPT-5-Codex.
- GLM-4.5-Air is cheaper at $0.20 / $1.10 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- GPT-5-Codex accepts more context: 400K tokens versus 131K.
- GLM-4.5-Air has downloadable open weights; the other is API-only.

## Snapshot

| | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Provider | Z.ai (Zhipu) | OpenAI |
| Noometry Index | 38.7 | 37.3 |
| Rank | 169 | 190 |
| Context | 131K | 400K |
| Input $/M | $0.20 | $1.25 |
| Output $/M | $1.10 | $10 |
| Weights | Open | Proprietary |

## Coding

- GLM-4.5-Air: 34.5 (#225)
- GPT-5-Codex: 41.9 (#100)

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| GSO | 2.9% | — |
| WeirdML | — | 54.5% |
| LMArena Coding | 1397 | — |

## Agentic & Tool Use

- GLM-4.5-Air: —
- GPT-5-Codex: 30.8 (#66)

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |

## Reasoning

- GLM-4.5-Air: 23.3 (#166)
- GPT-5-Codex: 30.0 (#80)

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | 43% | 70.3% |
| LMArena Hard Prompts | 1379 | — |
| ForecastBench | 59.2 | — |

## Math

- GLM-4.5-Air: 33.8 (#166)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Omni-MATH | 39.1% | — |
| LMArena Math | 1396 | — |

## Knowledge

- GLM-4.5-Air: 34.6 (#184)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Humanity's Last Exam | 8.1% | — |
| MMLU-Pro | 76.2% | — |
| Vectara Hallucination Rate | 9.3% | — |
| GPQA (HELM) | 59.4% | — |
| LMArena Expert | 1370 | — |

## Multilingual

- GLM-4.5-Air: 49.4 (#130)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1366 | — |
| LMArena Chinese | 1427 | — |
| LMArena French | 1399 | — |
| LMArena German | 1376 | — |
| LMArena Japanese | 1348 | — |
| LMArena Korean | 1306 | — |
| LMArena Russian | 1373 | — |
| LMArena Spanish | 1385 | — |

## Instruction Following

- GLM-4.5-Air: 69.8 (#165)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| IFEval | 81.2% | — |
| LMArena Instruction Following | 1353 | — |

## Long Context

- GLM-4.5-Air: 41.6 (#130)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1367 | — |

## Writing & Preference

- GLM-4.5-Air: 56.1 (#134)
- GPT-5-Codex: —

| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1384 | — |
| LMArena Creative Writing | 1343 | — |
| WildBench | 78.9% | — |
| LMArena Multi-Turn | 1371 | — |

## FAQ

### Is GLM-4.5-Air better than GPT-5-Codex?

GLM-4.5-Air is the stronger model overall, scoring 38.7 to 37.3 on the Noometry Index.

### Which is cheaper, GLM-4.5-Air or GPT-5-Codex?

GLM-4.5-Air is cheaper. It lists at $0.20 per million input tokens and $1.10 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

### Is GLM-4.5-Air or GPT-5-Codex better for coding?

GPT-5-Codex scores higher on coding benchmarks: 41.9 versus 34.5 in the Noometry coding category.

### Which has the bigger context window?

GPT-5-Codex does, with 400K tokens against 131K.

### How many benchmarks do GLM-4.5-Air and GPT-5-Codex share?

1 benchmark has published results for both models. GLM-4.5-Air has 27 scored results on Noometry and GPT-5-Codex has 3.