Model comparison
GLM-4.5-Air vs GPT-5-Codex
GLM-4.5-Air is the stronger model overall, scoring 38.9 to 37.9 on the Noometry Index.
Last verified . 1 shared benchmarks.
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 42.4 to 33.3.
- 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.
Side by side
| GLM-4.5-Air | GPT-5-Codex | |
|---|---|---|
| Provider | Z.ai (Zhipu) | OpenAI |
| Noometry Index | 38.9 | 37.9 |
| Released | 2025-07-20 | 2025-09-15 |
| Weights | Open | Proprietary |
| Context window | 131K | 400K |
| Max output | 98K | 128K |
| Input $ / M tokens | $0.20 | $1.25 |
| Output $ / M tokens | $1.10 | $10 |
| Results tracked | 27 | 3 |
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Category by category
Coding GPT-5-Codex leads
GLM-4.5-Air: 33.3 (#259), GPT-5-Codex: 42.4 (#103)
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| GSO | 2.9% | — |
| WeirdML | — | 54.5% |
| LMArena Coding | 1397 | — |
Agentic & Tool Use Not comparable
GLM-4.5-Air: —, GPT-5-Codex: 31.0 (#72)
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |
Reasoning GPT-5-Codex leads
GLM-4.5-Air: 24.1 (#166), GPT-5-Codex: 30.9 (#83)
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | 43% | 70.3% |
| LMArena Hard Prompts | 1379 | — |
| ForecastBench | 59.2 | — |
Math Not comparable
GLM-4.5-Air: 36.2 (#170), GPT-5-Codex: —
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| Omni-MATH | 39.1% | — |
| LMArena Math | 1396 | — |
Knowledge Not comparable
GLM-4.5-Air: 35.0 (#191), 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 Not comparable
GLM-4.5-Air: 49.1 (#135), GPT-5-Codex: —
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1366 | — |
| LMArena Chinese | 1426 | — |
| LMArena French | 1399 | — |
| LMArena German | 1377 | — |
| LMArena Japanese | 1348 | — |
| LMArena Korean | 1308 | — |
| LMArena Russian | 1373 | — |
| LMArena Spanish | 1386 | — |
Instruction Following Not comparable
GLM-4.5-Air: 69.6 (#171), GPT-5-Codex: —
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| IFEval | 81.2% | — |
| LMArena Instruction Following | 1354 | — |
Long Context Not comparable
GLM-4.5-Air: 41.6 (#135), GPT-5-Codex: —
| Benchmark | GLM-4.5-Air | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1366 | — |
Writing & Preference Not comparable
GLM-4.5-Air: 55.9 (#139), 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 | — |
Frequently asked questions
Is GLM-4.5-Air better than GPT-5-Codex?
GLM-4.5-Air is the stronger model overall, scoring 38.9 to 37.9 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: 42.4 versus 33.3 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.