Model comparison
GLM-5.1 vs Mercury 2
GLM-5.1 is the stronger model overall, scoring 47.8 to 39.1 on the Noometry Index. Mercury 2 costs 5.7× less per token, which makes it the better buy when GLM-5.1's lead doesn't matter for your workload.
Last verified . 16 shared benchmarks.
Summary
- They share 16 benchmarks with published results for both. GLM-5.1 scores higher in 7 categories and Mercury 2 in 0 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where GLM-5.1 leads 54.9 to 36.2.
- The biggest single-benchmark swing is WeirdML: 57.1% for GLM-5.1 and 43.2% for Mercury 2.
- Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $1.40 / $4.40 for GLM-5.1.
- GLM-5.1 accepts more context: 200K tokens versus 128K.
- GLM-5.1 has downloadable open weights; the other is API-only.
Side by side
| GLM-5.1 | Mercury 2 | |
|---|---|---|
| Provider | Z.ai (Zhipu) | Inception |
| Noometry Index | 47.8 | 39.1 |
| Released | 2026-04-07 | 2026-02-20 |
| Weights | Open | Proprietary |
| Context window | 200K | 128K |
| Max output | 131K | 50K |
| Input $ / M tokens | $1.40 | $0.25 |
| Output $ / M tokens | $4.40 | $0.75 |
| Results tracked | 41 | 17 |
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Category by category
Coding GLM-5.1 leads
GLM-5.1: 48.7 (#55), Mercury 2: 33.5 (#255)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena WebDev | 1508 | 1171 |
| SciCode | 43.8% | 38.7% |
| WeirdML | 57.1% | 43.2% |
| LMArena Coding | 1485 | 1391 |
| ALE-Bench | 887.1 | 785.58 |
| SWE-bench Verified | 74.2% | — |
Agentic & Tool Use Not comparable
GLM-5.1: 24.9 (#113), Mercury 2: —
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| APEX-Agents | 40.9% | — |
| ExploitBench | 18.1% | — |
| GBAEval | 0% | — |
| Vending-Bench 2 | 5,634 | — |
Reasoning GLM-5.1 leads
GLM-5.1: 39.1 (#60), Mercury 2: 23.8 (#170)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| CritPt | 4.6% | 0.8% |
| LMArena Hard Prompts | 1472 | 1362 |
| SimpleBench | 55.1% | — |
| NYT Connections (extended) | 77.7% | — |
| Chess Puzzles | 19% | — |
| Thematic Generalization | 69.8% | — |
| Epoch Capabilities Index | 149.84 | — |
Math Not comparable
GLM-5.1: 49.7 (#60), Mercury 2: —
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 36.8% | — |
| MathArena Final-Answer Competitions | 67.1% | — |
| OTIS Mock AIME 2024-2025 | 93.3% | — |
| ProofBench | 22.2% | — |
| LMArena Math | 1473 | — |
| FrontierMath (Feb 2025 set) | 33.4% | — |
| FrontierMath Tier 4 (v1) | 12.5% | — |
Knowledge GLM-5.1 leads
GLM-5.1: 54.9 (#50), Mercury 2: 36.2 (#172)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena Expert | 1476 | 1358 |
| GPQA Diamond | 89.9% | — |
| SimpleQA Verified | 34% | — |
| Vectara Hallucination Rate | — | 12.3% |
Multilingual GLM-5.1 leads
GLM-5.1: 55.0 (#36), Mercury 2: 46.6 (#157)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena Non-English | 1447 | 1331 |
| LMArena Chinese | 1515 | 1417 |
| LMArena Russian | 1454 | 1304 |
| LMArena French | 1474 | — |
| LMArena German | 1465 | — |
| LMArena Japanese | 1434 | — |
| LMArena Korean | 1418 | — |
| LMArena Spanish | 1469 | — |
Instruction Following GLM-5.1 leads
GLM-5.1: 76.3 (#42), Mercury 2: 70.2 (#165)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | 1451 | 1329 |
Long Context GLM-5.1 leads
GLM-5.1: 44.9 (#53), Mercury 2: 40.5 (#154)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena Longer Query | 1466 | 1330 |
Writing & Preference GLM-5.1 leads
GLM-5.1: 66.9 (#31), Mercury 2: 53.8 (#155)
| Benchmark | GLM-5.1 | Mercury 2 |
|---|---|---|
| LMArena Text | 1461 | 1355 |
| LMArena Creative Writing | 1453 | 1289 |
| LMArena Multi-Turn | 1472 | 1358 |
| EQ-Bench Creative Writing | 1592 | — |
Frequently asked questions
Is GLM-5.1 better than Mercury 2?
GLM-5.1 is the stronger model overall, scoring 47.8 to 39.1 on the Noometry Index. Mercury 2 costs 5.7× less per token, which makes it the better buy when GLM-5.1's lead doesn't matter for your workload.
Which is cheaper, GLM-5.1 or Mercury 2?
Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; GLM-5.1 lists at $1.40 and $4.40.
Is GLM-5.1 or Mercury 2 better for coding?
GLM-5.1 scores higher on coding benchmarks: 48.7 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
GLM-5.1 does, with 200K tokens against 128K.
How many benchmarks do GLM-5.1 and Mercury 2 share?
16 benchmarks have published results for both models. GLM-5.1 has 41 scored results on Noometry and Mercury 2 has 17.