# GLM-5.1 vs GPT-5.5 Pro

> GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 47.8 on the Noometry Index. GLM-5.1 costs 31× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/glm-5-1-vs-gpt-5-5-pro
- Last updated: 2026-10-12
- Shared benchmarks: 9

## Summary

- They share 9 benchmarks with published results for both. GLM-5.1 scores higher in 0 categories and GPT-5.5 Pro in 3 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.5 Pro leads 84.0 to 49.7.
- The biggest single-benchmark swing is FrontierMath (Tiers 1-3): 36.8% for GLM-5.1 and 87.7% for GPT-5.5 Pro.
- GLM-5.1 is cheaper at $1.40 / $4.40 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 200K.
- GLM-5.1 has downloadable open weights; the other is API-only.

## Snapshot

| | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| Provider | Z.ai (Zhipu) | OpenAI |
| Noometry Index | 47.8 | 64.3 |
| Rank | 59 | 8 |
| Context | 200K | 1.05M |
| Input $/M | $1.40 | $30 |
| Output $/M | $4.40 | $180 |
| Weights | Open | Proprietary |

## Coding

- GLM-5.1: 48.7 (#55)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified | 74.2% | — |
| LMArena WebDev | 1508 | — |
| SciCode | 43.8% | — |
| WeirdML | 57.1% | — |
| LMArena Coding | 1485 | — |
| ALE-Bench | 887.1 | — |

## Agentic & Tool Use

- GLM-5.1: 24.9 (#113)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| APEX-Agents | 40.9% | — |
| ExploitBench | 18.1% | — |
| GBAEval | 0% | — |
| Vending-Bench 2 | 5,634 | — |

## Reasoning

- GLM-5.1: 39.1 (#60)
- GPT-5.5 Pro: 73.3 (#10)

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| SimpleBench | 55.1% | 76.9% |
| CritPt | 4.6% | 30.6% |
| Chess Puzzles | 19% | 64% |
| Epoch Capabilities Index | 149.84 | 162.07 |
| ARC-AGI-2 | — | 84.6% |
| NYT Connections (extended) | 77.7% | — |
| ARC-AGI-1 | — | 96.5% |
| Thematic Generalization | 69.8% | — |
| LMArena Hard Prompts | 1472 | — |
| DTBench | — | 96% |
| LMCA | — | 53.9% |

## Math

- GLM-5.1: 49.7 (#60)
- GPT-5.5 Pro: 84.0 (#10)

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | 36.8% | 87.7% |
| OTIS Mock AIME 2024-2025 | 93.3% | 100% |
| FrontierMath (Feb 2025 set) | 33.4% | 52.4% |
| FrontierMath Tier 4 (v1) | 12.5% | 39.6% |
| FrontierMath Tier 4 | — | 78% |
| MathArena Final-Answer Competitions | 67.1% | — |
| ProofBench | 22.2% | — |
| LMArena Math | 1473 | — |

## Knowledge

- GLM-5.1: 54.9 (#50)
- GPT-5.5 Pro: 64.1 (#19)

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | 89.9% | 93.9% |
| SimpleQA Verified | 34% | — |
| LMArena Expert | 1476 | — |

## Multilingual

- GLM-5.1: 55.0 (#36)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| LMArena Non-English | 1447 | — |
| LMArena Chinese | 1515 | — |
| LMArena French | 1474 | — |
| LMArena German | 1465 | — |
| LMArena Japanese | 1434 | — |
| LMArena Korean | 1418 | — |
| LMArena Russian | 1454 | — |
| LMArena Spanish | 1469 | — |

## Instruction Following

- GLM-5.1: 76.3 (#42)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| LMArena Instruction Following | 1451 | — |

## Long Context

- GLM-5.1: 44.9 (#53)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| LMArena Longer Query | 1466 | — |

## Writing & Preference

- GLM-5.1: 66.9 (#31)
- GPT-5.5 Pro: —

| Benchmark | GLM-5.1 | GPT-5.5 Pro |
|---|---|---|
| LMArena Text | 1461 | — |
| LMArena Creative Writing | 1453 | — |
| EQ-Bench Creative Writing | 1592 | — |
| LMArena Multi-Turn | 1472 | — |

## FAQ

### Is GLM-5.1 better than GPT-5.5 Pro?

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 47.8 on the Noometry Index. GLM-5.1 costs 31× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

### Which is cheaper, GLM-5.1 or GPT-5.5 Pro?

GLM-5.1 is cheaper. It lists at $1.40 per million input tokens and $4.40 per million output tokens; GPT-5.5 Pro lists at $30 and $180.

### Which has the bigger context window?

GPT-5.5 Pro does, with 1.05M tokens against 200K.

### How many benchmarks do GLM-5.1 and GPT-5.5 Pro share?

9 benchmarks have published results for both models. GLM-5.1 has 41 scored results on Noometry and GPT-5.5 Pro has 14.