Model comparison
Claude Opus 5.5 vs GLM-5.3-Flash
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 51.8 on the Noometry Index. GLM-5.3-Flash costs 34× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 33 shared benchmarks.
Summary
- They share 33 benchmarks with published results for both. Claude Opus 5.5 scores higher in 10 categories and GLM-5.3-Flash in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 53.3.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Opus 5.5 and 21% for GLM-5.3-Flash.
- GLM-5.3-Flash is cheaper at $0.15 / $0.50 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- GLM-5.3-Flash has downloadable open weights; the other is API-only.
Side by side
| Claude Opus 5.5 | GLM-5.3-Flash | |
|---|---|---|
| Provider | Anthropic | Z.ai (Zhipu) |
| Noometry Index | 68.6 | 51.8 |
| Released | 2026-09-22 | 2026-08-20 |
| Weights | Proprietary | Open |
| Context window | 1M | 1M |
| Max output | 128K | 131K |
| Input $ / M tokens | $4 | $0.15 |
| Output $ / M tokens | $20 | $0.50 |
| Results tracked | 44 | 40 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.9 (#3), GLM-5.3-Flash: 53.1 (#31)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| FrontierCode | 54.6% | 31.8% |
| CursorBench | 57.8% | 36.8% |
| LMArena WebDev | 1813 | 1609 |
| FrontierSWE | 62.3% | 18.1% |
| SciCode | 66.9% | 51.6% |
| LMArena Coding | 1547 | 1508 |
| ALE-Bench | 2,147 | 303.55 |
| DeepSWE | — | 63.4% |
| MirrorCode | 77.4% | — |
Agentic & Tool Use Claude Opus 5.5 leads
Claude Opus 5.5: 45.3 (#15), GLM-5.3-Flash: 34.2 (#47)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| APEX-Agents | 73.5% | 52.8% |
| GDP.pdf | 30.6% | 14% |
| Vending-Bench 2 | 9,235 | — |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 80.2 (#3), GLM-5.3-Flash: 48.0 (#42)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| ARC-AGI-2 | 93.3% | 65.8% |
| ARC-AGI-1 | 98.5% | 91% |
| CritPt | 31.7% | 15.4% |
| LMArena Hard Prompts | 1535 | 1491 |
| Mystery Game Puzzles | 71% | 8% |
| Epoch Capabilities Index | 167.33 | 151.88 |
| NYT Connections (extended) | 88.5% | — |
| Chess Puzzles | — | 14% |
| EBR-Bench | 71.4% | — |
| DTBench | 98.9% | — |
| LMCA | 68.2% | — |
| Surface Evolver Bench | — | 52.5% |
| Bench to the Future 3 | — | 0.15 |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 91.8 (#3), GLM-5.3-Flash: 53.3 (#47)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 55.8% |
| FrontierMath Tier 4 | 95% | 17.1% |
| OTIS Mock AIME 2024-2025 | 100% | 93.9% |
| ProofBench | 100% | 21% |
| LMArena Math | 1506 | 1500 |
| FrontierMath Erdős | 2.9% | — |
Knowledge Claude Opus 5.5 leads
Claude Opus 5.5: 66.4 (#10), GLM-5.3-Flash: 58.4 (#36)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| GPQA Diamond | 90.6% | 90.2% |
| LMArena Expert | 1547 | 1513 |
| SimpleQA Verified | 72.2% | — |
Multimodal Claude Opus 5.5 leads
Claude Opus 5.5: 57.8 (#1), GLM-5.3-Flash: 42.8 (#27)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| LMArena Vision | 1321 | 1296 |
| Blueprint-Bench 2 | 51.2% | — |
| Furniture Assembly | 83.3% | — |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.1 (#2), GLM-5.3-Flash: 56.0 (#25)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| LMArena Non-English | 1507 | 1462 |
| LMArena Chinese | 1588 | 1527 |
| LMArena French | 1514 | 1496 |
| LMArena Russian | 1520 | 1469 |
| LMArena Spanish | 1507 | 1471 |
| LMArena German | — | 1470 |
| LMArena Japanese | — | 1429 |
| LMArena Korean | — | 1446 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.0 (#3), GLM-5.3-Flash: 77.5 (#20)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| LMArena Instruction Following | 1537 | 1478 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.1 (#19), GLM-5.3-Flash: 45.4 (#39)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| LMArena Longer Query | 1532 | 1482 |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.2 (#3), GLM-5.3-Flash: 65.3 (#50)
| Benchmark | Claude Opus 5.5 | GLM-5.3-Flash |
|---|---|---|
| LMArena Text | 1515 | 1471 |
| LMArena Creative Writing | 1533 | 1442 |
| LMArena Multi-Turn | 1499 | 1467 |
| EQ-Bench Creative Writing | 2050 | — |
Frequently asked questions
Is Claude Opus 5.5 better than GLM-5.3-Flash?
Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 51.8 on the Noometry Index. GLM-5.3-Flash costs 34× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 5.5 or GLM-5.3-Flash?
GLM-5.3-Flash is cheaper. It lists at $0.15 per million input tokens and $0.50 per million output tokens; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or GLM-5.3-Flash better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 53.1 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 5.5 and GLM-5.3-Flash share?
33 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and GLM-5.3-Flash has 40.