Model comparison
Claude Sonnet 5.5 vs GLM-5.1
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 47.6 on the Noometry Index. GLM-5.1 costs 1.9× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Last verified . 10 shared benchmarks.
Summary
- They share 10 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 5 categories and GLM-5.1 in 0 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 88.7 to 49.0.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 22.2% for GLM-5.1.
- GLM-5.1 is cheaper at $1.40 / $4.40 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 200K.
- GLM-5.1 has downloadable open weights; the other is API-only.
Side by side
| Claude Sonnet 5.5 | GLM-5.1 | |
|---|---|---|
| Provider | Anthropic | Z.ai (Zhipu) |
| Noometry Index | 60.5 | 47.6 |
| Released | 2026-09-28 | 2026-04-07 |
| Weights | Proprietary | Open |
| Context window | 1M | 200K |
| Max output | 128K | 131K |
| Input $ / M tokens | $2 | $1.40 |
| Output $ / M tokens | $10 | $4.40 |
| Results tracked | 16 | 41 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 65.5 (#6), GLM-5.1: 48.5 (#52)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| LMArena WebDev | 1699 | 1509 |
| SciCode | 61% | 43.8% |
| ALE-Bench | 1,819 | 887.1 |
| SWE-bench Verified | — | 74.2% |
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| FrontierSWE | 61.9% | — |
| WeirdML | — | 57.1% |
| LMArena Coding | — | 1486 |
Agentic & Tool Use Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 44.9 (#14), GLM-5.1: 24.8 (#106)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| APEX-Agents | 75.5% | 40.9% |
| ExploitBench | — | 18.1% |
| GBAEval | — | 0% |
| Vending-Bench 2 | — | 5,634 |
Reasoning Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 52.4 (#29), GLM-5.1: 38.2 (#57)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| CritPt | 31.4% | 4.6% |
| SimpleBench | — | 55.1% |
| NYT Connections (extended) | — | 77.7% |
| Chess Puzzles | — | 19% |
| Thematic Generalization | — | 69.8% |
| LMArena Hard Prompts | — | 1472 |
| Mystery Game Puzzles | 65% | — |
| Epoch Capabilities Index | — | 149.86 |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 88.7 (#4), GLM-5.1: 49.0 (#48)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 36.8% |
| OTIS Mock AIME 2024-2025 | 100% | 93.3% |
| ProofBench | 100% | 22.2% |
| FrontierMath Tier 4 | 80.5% | — |
| MathArena Final-Answer Competitions | — | 67.1% |
| LMArena Math | — | 1472 |
| FrontierMath (Feb 2025 set) | — | 33.4% |
| FrontierMath Tier 4 (v1) | — | 12.5% |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#11), GLM-5.1: 55.0 (#45)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| GPQA Diamond | 95.6% | 89.9% |
| SimpleQA Verified | 46.5% | 34% |
| LMArena Expert | — | 1477 |
Multimodal Not comparable
Claude Sonnet 5.5: 53.2 (#5), GLM-5.1: —
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| Furniture Assembly | 75% | — |
Multilingual Not comparable
Claude Sonnet 5.5: —, GLM-5.1: 55.2 (#34)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| LMArena Non-English | — | 1448 |
| LMArena Chinese | — | 1516 |
| LMArena French | — | 1478 |
| LMArena German | — | 1466 |
| LMArena Japanese | — | 1436 |
| LMArena Korean | — | 1423 |
| LMArena Russian | — | 1453 |
| LMArena Spanish | — | 1467 |
Instruction Following Not comparable
Claude Sonnet 5.5: —, GLM-5.1: 76.5 (#41)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| LMArena Instruction Following | — | 1451 |
Long Context Not comparable
Claude Sonnet 5.5: —, GLM-5.1: 44.9 (#51)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| LMArena Longer Query | — | 1467 |
Writing & Preference Not comparable
Claude Sonnet 5.5: —, GLM-5.1: 67.2 (#29)
| Benchmark | Claude Sonnet 5.5 | GLM-5.1 |
|---|---|---|
| LMArena Text | — | 1462 |
| LMArena Creative Writing | — | 1454 |
| EQ-Bench Creative Writing | — | 1592 |
| LMArena Multi-Turn | — | 1473 |
Frequently asked questions
Is Claude Sonnet 5.5 better than GLM-5.1?
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 47.6 on the Noometry Index. GLM-5.1 costs 1.9× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 5.5 or GLM-5.1?
GLM-5.1 is cheaper. It lists at $1.40 per million input tokens and $4.40 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.
Is Claude Sonnet 5.5 or GLM-5.1 better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 48.5 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 5.5 does, with 1M tokens against 200K.
How many benchmarks do Claude Sonnet 5.5 and GLM-5.1 share?
10 benchmarks have published results for both models. Claude Sonnet 5.5 has 16 scored results on Noometry and GLM-5.1 has 41.