Model comparison
Claude 2.1 vs Claude Sonnet 4.5
Claude Sonnet 4.5 is the stronger model overall, scoring 44.0 to 24.9 on the Noometry Index.
Last verified . 6 shared benchmarks.
Summary
- They share 6 benchmarks with published results for both. Claude 2.1 scores higher in 0 categories and Claude Sonnet 4.5 in 4 categories; 4 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Claude Sonnet 4.5 leads 48.4 to 15.5.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 1.9% for Claude 2.1 and 77.8% for Claude Sonnet 4.5.
Side by side
| Claude 2.1 | Claude Sonnet 4.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 24.9 | 44.0 |
| Released | 2023-11-21 | 2025-09-29 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1M |
| Max output | — | 64K |
| Input $ / M tokens | — | $3 |
| Output $ / M tokens | — | $15 |
| Results tracked | 7 | 73 |
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Category by category
Coding Claude Sonnet 4.5 leads
Claude 2.1: 25.8 (#322), Claude Sonnet 4.5: 47.8 (#54)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| WeirdML | 7.1% | 47.7% |
| SWE-bench Verified | — | 71.3% |
| SWE-bench Verified (bash only) | — | 71.4% |
| LMArena WebDev | — | 1393 |
| SWE-bench Multilingual | — | 67% |
| SciCode | — | 44.7% |
| GSO | — | 14.7% |
| LMArena Coding | — | 1489 |
| ALE-Bench | — | 796.15 |
| AlgoTune | — | 1.52 |
Agentic & Tool Use Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 38.1 (#30)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| Terminal-Bench | — | 46.5% |
| Berkeley Function Calling Leaderboard | — | 73.2% |
| GDPval | — | 42.5% |
| Remote Labor Index | — | 2.1% |
| τ²-bench Airline | — | 72% |
| τ²-bench Banking | — | 25.3% |
| τ²-bench Retail | — | 72.4% |
| τ²-bench Telecom | — | 84.9% |
| Cybench | — | 60% |
| DeepResearch Bench | — | 52.6% |
| OSWorld | — | 62.9% |
| LMArena Search | — | 1159 |
| METR Time Horizons | — | 67.4% |
| Vending-Bench 2 | — | 3,839 |
Reasoning Claude Sonnet 4.5 leads
Claude 2.1: 20.6 (#216), Claude Sonnet 4.5: 26.9 (#113)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| DTBench | 51% | 83.2% |
| Epoch Capabilities Index | 119.22 | 146.84 |
| ForecastBench | 54.2 | 61.9 |
| ARC-AGI-2 | — | 13.6% |
| SimpleBench | — | 54.3% |
| Kagi LLM Benchmark | — | 57.9% |
| NYT Connections (extended) | — | 37.3% |
| ARC-AGI-1 | — | 63.7% |
| CritPt | — | 1.1% |
| Chess Puzzles | — | 12% |
| EnigmaEval | — | 6% |
| EBR-Bench | — | 2.4% |
| LMArena Hard Prompts | — | 1462 |
| Mystery Game Puzzles | — | 17% |
| LMCA | — | 38.8% |
Math Claude Sonnet 4.5 leads
Claude 2.1: 9.6 (#309), Claude Sonnet 4.5: 31.9 (#190)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 1.9% | 77.8% |
| FrontierMath (Tiers 1-3) | — | 23.9% |
| FrontierMath Tier 4 | — | 2.4% |
| ProofBench | — | 19% |
| Omni-MATH | — | 55.3% |
| LMArena Math | — | 1448 |
| MATH Level 5 | — | 97.7% |
| FrontierMath (Feb 2025 set) | — | 15.2% |
| FrontierMath Tier 4 (v1) | — | 4.2% |
Knowledge Claude Sonnet 4.5 leads
Claude 2.1: 15.5 (#287), Claude Sonnet 4.5: 48.4 (#70)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| GPQA Diamond | 33% | 82.3% |
| Humanity's Last Exam | — | 13.7% |
| SimpleQA Verified | — | 30.7% |
| MMLU-Pro | — | 86.9% |
| Vectara Hallucination Rate | — | 12% |
| GPQA (HELM) | — | 68.6% |
| LMArena Expert | — | 1483 |
| MMLU | 73.5% | — |
Multimodal Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 34.1 (#84)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| VPCT | — | 39.8% |
| LMArena Document | — | 1450 |
Multilingual Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 53.6 (#65)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| LMArena Non-English | — | 1425 |
| LMArena Chinese | — | 1459 |
| LMArena French | — | 1459 |
| LMArena German | — | 1427 |
| LMArena Japanese | — | 1390 |
| LMArena Korean | — | 1403 |
| LMArena Russian | — | 1436 |
| LMArena Spanish | — | 1457 |
Instruction Following Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 75.2 (#74)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| IFEval | — | 85% |
| LMArena Instruction Following | — | 1459 |
Long Context Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 45.2 (#45)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| LMArena Longer Query | — | 1476 |
Writing & Preference Not comparable
Claude 2.1: —, Claude Sonnet 4.5: 66.7 (#33)
| Benchmark | Claude 2.1 | Claude Sonnet 4.5 |
|---|---|---|
| LMArena Text | — | 1439 |
| LMArena Creative Writing | — | 1442 |
| EQ-Bench Creative Writing | — | 1678 |
| WildBench | — | 85.4% |
| LMArena Multi-Turn | — | 1465 |
Frequently asked questions
Is Claude 2.1 better than Claude Sonnet 4.5?
Claude Sonnet 4.5 is the stronger model overall, scoring 44.0 to 24.9 on the Noometry Index.
Is Claude 2.1 or Claude Sonnet 4.5 better for coding?
Claude Sonnet 4.5 scores higher on coding benchmarks: 47.8 versus 25.8 in the Noometry coding category.
How many benchmarks do Claude 2.1 and Claude Sonnet 4.5 share?
6 benchmarks have published results for both models. Claude 2.1 has 7 scored results on Noometry and Claude Sonnet 4.5 has 73.