Model comparison
GLM-4.5-Air vs GPT-5.1
GPT-5.1 is the stronger model overall, scoring 49.0 to 38.9 on the Noometry Index. GLM-4.5-Air costs 8.1× less per token, which makes it the better buy when GPT-5.1's lead doesn't matter for your workload.
Last verified . 26 shared benchmarks.
Summary
- They share 26 benchmarks with published results for both. GLM-4.5-Air scores higher in 0 categories and GPT-5.1 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.1 leads 52.2 to 36.2.
- The biggest single-benchmark swing is MMLU-Pro: 76.2% for GLM-4.5-Air and 57.9% for GPT-5.1.
- GLM-4.5-Air is cheaper at $0.20 / $1.10 per million input/output tokens, against $1.25 / $10 for GPT-5.1.
- GPT-5.1 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-5.1 | |
|---|---|---|
| Provider | Z.ai (Zhipu) | OpenAI |
| Noometry Index | 38.9 | 49.0 |
| Released | 2025-07-20 | 2025-11-13 |
| 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 | 63 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding GPT-5.1 leads
GLM-4.5-Air: 33.3 (#259), GPT-5.1: 46.4 (#66)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| GSO | 2.9% | 13.7% |
| LMArena Coding | 1397 | 1454 |
| SWE-bench Verified | — | 68% |
| SWE-bench Verified (bash only) | — | 66% |
| LMArena WebDev | — | 1395 |
| SciCode | — | 43.3% |
| WeirdML | — | 60.8% |
| LiveBench Coding | — | 72.5% |
| ALE-Bench | — | 1,192 |
Agentic & Tool Use Not comparable
GLM-4.5-Air: —, GPT-5.1: 32.7 (#60)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| Terminal-Bench | — | 47.6% |
| DeepResearch Bench | — | 42.8% |
| LMArena Search | — | 1199 |
| Vending-Bench 2 | — | 1,473 |
Reasoning GPT-5.1 leads
GLM-4.5-Air: 24.1 (#166), GPT-5.1: 39.8 (#58)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| LMArena Hard Prompts | 1379 | 1457 |
| ForecastBench | 59.2 | 58.1 |
| ARC-AGI-2 | — | 17.6% |
| SimpleBench | — | 53.2% |
| Kagi LLM Benchmark | 43% | — |
| ARC-AGI-1 | — | 72.8% |
| CritPt | — | 4.9% |
| Chess Puzzles | — | 32% |
| EnigmaEval | — | 11.2% |
| LiveBench Reasoning | — | 95.8% |
| Mystery Game Puzzles | — | 19% |
| DTBench | — | 90.1% |
| LiveBench Data Analysis | — | 72.1% |
| LMCA | — | 43.9% |
| Epoch Capabilities Index | — | 149.64 |
| LiveBench | — | 78.8% |
Math GPT-5.1 leads
GLM-4.5-Air: 36.2 (#170), GPT-5.1: 52.2 (#51)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| Omni-MATH | 39.1% | 46.4% |
| LMArena Math | 1396 | 1447 |
| OTIS Mock AIME 2024-2025 | — | 88.6% |
| LiveBench Math | — | 94.5% |
| FrontierMath (Feb 2025 set) | — | 31% |
| FrontierMath Tier 4 (v1) | — | 12.5% |
Knowledge GPT-5.1 leads
GLM-4.5-Air: 35.0 (#191), GPT-5.1: 50.6 (#71)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| Humanity's Last Exam | 8.1% | 23.7% |
| MMLU-Pro | 76.2% | 57.9% |
| Vectara Hallucination Rate | 9.3% | 10.9% |
| GPQA (HELM) | 59.4% | 44.2% |
| LMArena Expert | 1370 | 1470 |
| GPQA Diamond | — | 87.6% |
| SimpleQA Verified | — | 48% |
Multimodal Not comparable
GLM-4.5-Air: —, GPT-5.1: 44.8 (#19)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| LMArena Vision | — | 1250 |
| VPCT | — | 58.7% |
| LMArena Document | — | 1403 |
Multilingual GPT-5.1 leads
GLM-4.5-Air: 49.1 (#135), GPT-5.1: 53.8 (#56)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| LMArena Non-English | 1366 | 1431 |
| LMArena Chinese | 1426 | 1495 |
| LMArena French | 1399 | 1450 |
| LMArena German | 1377 | 1438 |
| LMArena Japanese | 1348 | 1453 |
| LMArena Korean | 1308 | 1401 |
| LMArena Russian | 1373 | 1435 |
| LMArena Spanish | 1386 | 1433 |
Instruction Following GPT-5.1 leads
GLM-4.5-Air: 69.6 (#171), GPT-5.1: 83.9 (#1)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| IFEval | 81.2% | 93.5% |
| LMArena Instruction Following | 1354 | 1443 |
| LiveBench Instruction Following | — | 93.3% |
Long Context GPT-5.1 leads
GLM-4.5-Air: 41.6 (#135), GPT-5.1: 47.6 (#14)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| LMArena Longer Query | 1366 | 1447 |
| CL-bench | — | 23.7% |
| CL-bench Life | — | 17.3% |
Writing & Preference GPT-5.1 leads
GLM-4.5-Air: 55.9 (#139), GPT-5.1: 64.5 (#55)
| Benchmark | GLM-4.5-Air | GPT-5.1 |
|---|---|---|
| LMArena Text | 1384 | 1443 |
| LMArena Creative Writing | 1343 | 1427 |
| WildBench | 78.9% | 86.3% |
| LMArena Multi-Turn | 1371 | 1450 |
| LiveBench Language | — | 80.2% |
Frequently asked questions
Is GLM-4.5-Air better than GPT-5.1?
GPT-5.1 is the stronger model overall, scoring 49.0 to 38.9 on the Noometry Index. GLM-4.5-Air costs 8.1× less per token, which makes it the better buy when GPT-5.1's lead doesn't matter for your workload.
Which is cheaper, GLM-4.5-Air or GPT-5.1?
GLM-4.5-Air is cheaper. It lists at $0.20 per million input tokens and $1.10 per million output tokens; GPT-5.1 lists at $1.25 and $10.
Is GLM-4.5-Air or GPT-5.1 better for coding?
GPT-5.1 scores higher on coding benchmarks: 46.4 versus 33.3 in the Noometry coding category.
Which has the bigger context window?
GPT-5.1 does, with 400K tokens against 131K.
How many benchmarks do GLM-4.5-Air and GPT-5.1 share?
26 benchmarks have published results for both models. GLM-4.5-Air has 27 scored results on Noometry and GPT-5.1 has 63.