Model comparison
GLM-5.1 vs GPT-5.5 Pro
Head-to-head evidence from 5 shared benchmark results across 4 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GLM-5.1 #18 (Supported); GPT-5.5 Pro #38 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GLM-5.1 and GPT-5.5 Pro share 5 comparable benchmark results. 3 of 8 categories are comparable. 31 results are unique to GLM-5.1; 2 to GPT-5.5 Pro.
Updated July 22, 2026- Shared results
- 5
- GLM-5.1 only
- 31
- GPT-5.5 Pro only
- 2
- Comparable categories
- 3 / 8
Pick GLM-5.1 if you want the stronger benchmark profile. GPT-5.5 Pro only becomes the better choice if agentic is the priority or you need the larger 1M context window.
Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 4 evidence categories; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GLM-5.1 is clearly ahead on the BenchAlign aggregate, 67.74 to 63.69. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GLM-5.1's sharpest advantage is in mathematics, where it averages 62 against 48.1. The single biggest benchmark swing on the page is FrontierMath v2 (Tier 4), 12.500% to 39.600%. GPT-5.5 Pro does hit back in agentic, so the answer changes if that is the part of the workload you care about most.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $1.40 input / $4.40 output per 1M tokens for GLM-5.1. That is roughly 40.9x on output cost alone. GPT-5.5 Pro gives you the larger context window at 1M, compared with 203K for GLM-5.1.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | GLM-5.1 | Δ | GPT-5.5 Pro |
|---|---|---|---|
| Agentic | GLM-5.165.4 | Margin→ 24.7 | GPT-5.5 Pro90.1 |
| Math | GLM-5.162.0 | Margin← 13.9 | GPT-5.5 Pro48.1 |
| Knowledge | GLM-5.152.3 | Margin→ 4.9 | GPT-5.5 Pro57.2 |
| Coding | GLM-5.161.3 | MarginNo overlap | GPT-5.5 ProNot measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tier 4)
MathA 12.500%B 39.600%Winner: GPT-5.5 ProΔ 27.1FrontierMath v2 (Tier 4): GLM-5.1 scored 12.500%; GPT-5.5 Pro scored 39.600%. GPT-5.5 Pro wins this benchmark. - Source ↗
BrowseComp
AgenticA 68%B 90.1%Winner: GPT-5.5 ProΔ 22.1BrowseComp: GLM-5.1 scored 68%; GPT-5.5 Pro scored 90.1%. GPT-5.5 Pro wins this benchmark. - Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 33.448%B 51.000%Winner: GPT-5.5 ProΔ 17.6FrontierMath v2 (Tiers 1-3): GLM-5.1 scored 33.448%; GPT-5.5 Pro scored 51.000%. GPT-5.5 Pro wins this benchmark. - Source ↗
HLE
KnowledgeA 52.3%B 57.2%Winner: GPT-5.5 ProΔ 4.9HLE: GLM-5.1 scored 52.3%; GPT-5.5 Pro scored 57.2%. GPT-5.5 Pro wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GLM-5.1 | GPT-5.5 Pro | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GLM-5.1$1.4 input / $4.4 output | GPT-5.5 Pro$30 input / $180 output | GLM-5.1 has the lower combined listed price. |
| Generation speedtokens per second | GLM-5.1Not available | GPT-5.5 ProNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GLM-5.1Not available | GPT-5.5 ProNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GLM-5.1203K | GPT-5.5 Pro1M | GPT-5.5 Pro lists the larger context window. |
Benchmark Deep Dive
AgenticGPT-5.5 Pro wins12 benchmarks
| Benchmark | GLM-5.1 | GPT-5.5 Pro | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 63.5% | — | Not comparable |
| BrowseCompSource | 68% | 90.1% | GPT-5.5 Pro leads |
| τ³-bench resultsSource | 70.6% | — | Not comparable |
| MCP AtlasSource | 71.8% | — | Not comparable |
| CyberGymSource | 68.7% | — | Not comparable |
| Claw-EvalSource | 62.3% | — | Not comparable |
| AA Agentic IndexSource | 29.9% | — | Not comparable |
| τ²-bench resultsSource | 97.7% | — | Not comparable |
| GDPval-AASource | 37.8% | — | Not comparable |
| Gert LabsSource | 60.11% | — | Not comparable |
| GDPval-AASource | 1257 | — | Not comparable |
| ResearchClawBenchSource | 18.2% | — | Not comparable |
Coding6 benchmarks
Reasoning2 benchmarks
KnowledgeGPT-5.5 Pro wins9 benchmarks
| Benchmark | GLM-5.1 | GPT-5.5 Pro | Result |
|---|---|---|---|
| GPQA-DSource | 86.2% | — | Not comparable |
| HLESource | 52.3% | 57.2% | GPT-5.5 Pro leads |
| Artificial Analysis Intelligence IndexSource | 40.2% | — | Not comparable |
| AA-GPQA DiamondSource | 86.8% | — | Not comparable |
| AA-HLESource | 28.0% | — | Not comparable |
| AA-Omniscience IndexSource | 1.9% | — | Not comparable |
| AA-Omniscience AccuracySource | 24.2% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 29.4% | — | Not comparable |
| HLE w/o toolsSource | — | 43.1% | Not comparable |
MathGLM-5.1 wins7 benchmarks
| Benchmark | GLM-5.1 | GPT-5.5 Pro | Result |
|---|---|---|---|
| AIME26Source | 95.3% | — | Not comparable |
| HMMT Nov 2025Source | 94.0% | — | Not comparable |
| HMMT Feb 2026Source | 82.6% | — | Not comparable |
| MMAnswerBenchSource | 83.8% | — | Not comparable |
| FrontierMath v2 (Tiers 1-3)Source | 33.448% | 51.000% | GPT-5.5 Pro leads |
| FrontierMath v2 (Tier 4)Source | 12.500% | 39.600% | GPT-5.5 Pro leads |
| FrontierMath (legacy)Source | — | 52.4% | Not comparable |
Multimodal1 benchmarks
| Benchmark | GLM-5.1 | GPT-5.5 Pro | Result |
|---|---|---|---|
| Design Arena WebsiteSource | 1305 | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | GLM-5.1 | GPT-5.5 Pro | Result |
|---|---|---|---|
| AA-IFBenchSource | 76.3% | — | Not comparable |
Frequently Asked Questions (4)
Which is better, GLM-5.1 or GPT-5.5 Pro?
GLM-5.1 is ahead on BenchLM's BenchAlign leaderboard, 67.74 to 63.69. The biggest single separator in this matchup is FrontierMath v2 (Tier 4), where the scores are 12.500% and 39.600%.
Which is better for knowledge tasks, GLM-5.1 or GPT-5.5 Pro?
GPT-5.5 Pro has the edge for knowledge tasks in this comparison, averaging 57.2 versus 52.3. Inside this category, HLE is the benchmark that creates the most daylight between them.
Which is better for math, GLM-5.1 or GPT-5.5 Pro?
GLM-5.1 has the edge for math in this comparison, averaging 62 versus 48.1. Inside this category, FrontierMath v2 (Tier 4) is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, GLM-5.1 or GPT-5.5 Pro?
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 65.4. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.
Self-host vs API cost
Estimates at 50,000 req/day · 1000 tokens/req average.
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