Model comparison
Claude Sonnet 4 vs Mercury 2
Claude Sonnet 4 is the stronger model overall, scoring 40.8 to 39.1 on the Noometry Index. Mercury 2 costs 16× less per token, which makes it the better buy when Claude Sonnet 4's lead doesn't matter for your workload.
Last verified . 16 shared benchmarks.
Summary
- They share 16 benchmarks with published results for both. Claude Sonnet 4 scores higher in 5 categories and Mercury 2 in 2 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in coding, where Claude Sonnet 4 leads 43.5 to 33.5.
- Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $3 / $15 for Claude Sonnet 4.
- Claude Sonnet 4 accepts more context: 200K tokens versus 128K.
Side by side
| Claude Sonnet 4 | Mercury 2 | |
|---|---|---|
| Provider | Anthropic | Inception |
| Noometry Index | 40.8 | 39.1 |
| Released | 2025-05-22 | 2026-02-20 |
| Weights | Proprietary | Proprietary |
| Context window | 200K | 128K |
| Max output | 64K | 50K |
| Input $ / M tokens | $3 | $0.25 |
| Output $ / M tokens | $15 | $0.75 |
| Results tracked | 58 | 17 |
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Category by category
Coding Claude Sonnet 4 leads
Claude Sonnet 4: 43.5 (#88), Mercury 2: 33.5 (#255)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| SciCode | 40% | 38.7% |
| WeirdML | 46.1% | 43.2% |
| LMArena Coding | 1414 | 1391 |
| ALE-Bench | 655.35 | 785.58 |
| SWE-bench Verified (bash only) | 64.9% | — |
| Aider Polyglot | 61.3% | — |
| LMArena WebDev | — | 1171 |
| GSO | 4.9% | — |
Agentic & Tool Use Not comparable
Claude Sonnet 4: 38.5 (#31), Mercury 2: —
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| TheAgentCompany | 33.1% | — |
| Cybench | 35% | — |
| DeepResearch Bench | 46.6% | — |
| OSWorld | 43.9% | — |
| METR Time Horizons | 62% | — |
Reasoning Too close to call
Claude Sonnet 4: 22.9 (#187), Mercury 2: 23.8 (#170)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| CritPt | 0.3% | 0.8% |
| LMArena Hard Prompts | 1372 | 1362 |
| ARC-AGI-2 | 5.9% | — |
| SimpleBench | 45.5% | — |
| Kagi LLM Benchmark | 73% | — |
| ARC-AGI-1 | 40% | — |
| EnigmaEval | 3.1% | — |
| DTBench | 77.1% | — |
| LMCA | 29% | — |
| Epoch Capabilities Index | 141.69 | — |
| ForecastBench | 60.2 | — |
Math Not comparable
Claude Sonnet 4: 43.3 (#80), Mercury 2: —
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 71.1% | — |
| Omni-MATH | 60.2% | — |
| LMArena Math | 1375 | — |
| MATH Level 5 | 84.4% | — |
| FrontierMath (Feb 2025 set) | 4.1% | — |
| FrontierMath Tier 4 (v1) | 0% | — |
Knowledge Claude Sonnet 4 leads
Claude Sonnet 4: 41.8 (#108), Mercury 2: 36.2 (#172)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| Vectara Hallucination Rate | 10.3% | 12.3% |
| LMArena Expert | 1372 | 1358 |
| GPQA Diamond | 79.2% | — |
| Humanity's Last Exam | 7.8% | — |
| MMLU-Pro | 84.3% | — |
| Confabulations | 13.2% | — |
| GPQA (HELM) | 70.6% | — |
Multimodal Not comparable
Claude Sonnet 4: 26.2 (#121), Mercury 2: —
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| LMArena Vision | 1191 | — |
| GeoBench | 37% | — |
| VPCT | 34% | — |
| MindCube | 44.8% | — |
Multilingual Too close to call
Claude Sonnet 4: 46.7 (#156), Mercury 2: 46.6 (#157)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| LMArena Non-English | 1333 | 1331 |
| LMArena Chinese | 1350 | 1417 |
| LMArena Russian | 1355 | 1304 |
| LMArena French | 1363 | — |
| LMArena German | 1331 | — |
| LMArena Japanese | 1302 | — |
| LMArena Korean | 1291 | — |
| LMArena Spanish | 1357 | — |
Instruction Following Claude Sonnet 4 leads
Claude Sonnet 4: 71.7 (#145), Mercury 2: 70.2 (#165)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | 1376 | 1329 |
| IFEval | 84% | — |
Long Context Mercury 2 leads
Claude Sonnet 4: 33.7 (#259), Mercury 2: 40.5 (#154)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| LMArena Longer Query | 1398 | 1330 |
| Fiction.LiveBench | 46.9% | — |
Writing & Preference Claude Sonnet 4 leads
Claude Sonnet 4: 57.1 (#132), Mercury 2: 53.8 (#155)
| Benchmark | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| LMArena Text | 1351 | 1355 |
| LMArena Creative Writing | 1345 | 1289 |
| LMArena Multi-Turn | 1376 | 1358 |
| Short-Story Creative Writing | 81.4% | — |
| EQ-Bench Creative Writing | 1483 | — |
| WildBench | 83.8% | — |
Frequently asked questions
Is Claude Sonnet 4 better than Mercury 2?
Claude Sonnet 4 is the stronger model overall, scoring 40.8 to 39.1 on the Noometry Index. Mercury 2 costs 16× less per token, which makes it the better buy when Claude Sonnet 4's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 4 or Mercury 2?
Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; Claude Sonnet 4 lists at $3 and $15.
Is Claude Sonnet 4 or Mercury 2 better for coding?
Claude Sonnet 4 scores higher on coding benchmarks: 43.5 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 4 does, with 200K tokens against 128K.
How many benchmarks do Claude Sonnet 4 and Mercury 2 share?
16 benchmarks have published results for both models. Claude Sonnet 4 has 58 scored results on Noometry and Mercury 2 has 17.