Compare / head-to-head
GLM-5.1vsGPT-5.5 Pro
GPT-5.5 Pro leads 1 of 1 shared benchmark. GLM-5.1 is 36.2x cheaper per token. GPT-5.5 Pro has the larger context window (1.1M tokens).
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
0 – 1
GPT-5.5 Pro leads
Cheaper per token
GLM-5.1
36.2x cheaper, input + output
Larger context
GPT-5.5 Pro
1.1M tokens
Provider uptime (30d)
— · 94.2446%
Z.ai · OpenAI
GLM-5.1
Z.ai · released 2026-04-07
text
GPT-5.5 Pro
OpenAI · released 2026-04-23
textvision
Quality
Benchmark matrix
1 shared · 6 only GLM-5.1 · 7 only GPT-5.5 Pro| Benchmark | GLM-5.1 | GPT-5.5 Pro | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 1 | ||||
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 36.8% ↗epoch | 87.7% ↗epoch | -50.9 pt | GPT-5.5 Pro |
| Only GLM-5.1 reports · 6 | ||||
| GPQA Diamond | 89.9% ↗epoch | not reported | — | — |
| AIME 2026 | 95.8% ↗matharena ⚠ | not reported | — | — |
| LMArena Elo | 1462.4 ↗ | not reported | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 93.3% ↗epoch | not reported | — | — |
| SimpleQA Verified | 34% ↗epoch | not reported | — | — |
| SWE-bench Verified (Epoch AI run) | 74.2% ↗epoch | not reported | — | — |
| Only GPT-5.5 Pro reports · 7 | ||||
| Humanity's Last Exam (no tools) | not reported | 43.1% ↗ | — | — |
| BrowseComp | not reported | 90.1% ↗ | — | — |
| FrontierMath Tier 1-3 | not reported | 52.4% ↗ | — | — |
| FrontierMath Tier 4 | not reported | 39.6% ↗ | — | — |
| FrontierMath Tier 4 v2 (Epoch AI run) | not reported | 78% ↗epoch | — | — |
| GDPval (wins or ties) | not reported | 82.3% ↗ | — | — |
| Humanity's Last Exam (with tools) | not reported | 57.2% ↗ | — | — |
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is GLM-5.1 minus GPT-5.5 Pro in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | GLM-5.1 | GPT-5.5 Pro | Edge |
|---|---|---|---|
| Context window | 200K tokens | 1.1M tokens | GPT-5.5 Pro |
| Max output | 131K tokens | 128K tokens | GLM-5.1 |
| Input price / 1M | $1.4 ↗ | $30 ↗ | GLM-5.1 |
| Output price / 1M | $4.4 ↗ | $180 ↗ | GLM-5.1 |
| Cached input / 1M | $0.26 ↗ | — | — |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $5.8 | $210 | GLM-5.1 |
| Modalities | text | text · vision | GPT-5.5 Pro |
| Released | 2026-04-07 | 2026-04-23 | — |
| Cited benchmark scores | 7 | 8 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
GLM-5.1 vs …
Models sharing the most benchmarksMore matchups
GPT-5.5 Pro vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run GLM-5.1 and GPT-5.5 Pro on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.