Model comparison
Claude 2.1 vs Claude Sonnet 5.5
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 24.9 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. Claude 2.1 scores higher in 0 categories and Claude Sonnet 5.5 in 4 categories; 4 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 88.7 to 9.6.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 1.9% for Claude 2.1 and 100% for Claude Sonnet 5.5.
Side by side
| Claude 2.1 | Claude Sonnet 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 24.9 | 60.5 |
| Released | 2023-11-21 | 2026-09-28 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1M |
| Max output | — | 128K |
| Input $ / M tokens | — | $2 |
| Output $ / M tokens | — | $10 |
| Results tracked | 7 | 16 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude 2.1: 25.8 (#322), Claude Sonnet 5.5: 65.5 (#6)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| FrontierCode | — | 52.1% |
| CursorBench | — | 55.5% |
| LMArena WebDev | — | 1699 |
| FrontierSWE | — | 61.9% |
| SciCode | — | 61% |
| WeirdML | 7.1% | — |
| ALE-Bench | — | 1,819 |
Agentic & Tool Use Not comparable
Claude 2.1: —, Claude Sonnet 5.5: 44.9 (#14)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| APEX-Agents | — | 75.5% |
Reasoning Claude Sonnet 5.5 leads
Claude 2.1: 20.6 (#216), Claude Sonnet 5.5: 52.4 (#29)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| CritPt | — | 31.4% |
| Mystery Game Puzzles | — | 65% |
| DTBench | 51% | — |
| Epoch Capabilities Index | 119.22 | — |
| ForecastBench | 54.2 | — |
Math Claude Sonnet 5.5 leads
Claude 2.1: 9.6 (#309), Claude Sonnet 5.5: 88.7 (#4)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 1.9% | 100% |
| FrontierMath (Tiers 1-3) | — | 88.8% |
| FrontierMath Tier 4 | — | 80.5% |
| ProofBench | — | 100% |
Knowledge Claude Sonnet 5.5 leads
Claude 2.1: 15.5 (#287), Claude Sonnet 5.5: 66.0 (#11)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| GPQA Diamond | 33% | 95.6% |
| SimpleQA Verified | — | 46.5% |
| MMLU | 73.5% | — |
Multimodal Not comparable
Claude 2.1: —, Claude Sonnet 5.5: 53.2 (#5)
| Benchmark | Claude 2.1 | Claude Sonnet 5.5 |
|---|---|---|
| Furniture Assembly | — | 75% |
Frequently asked questions
Is Claude 2.1 better than Claude Sonnet 5.5?
Claude Sonnet 5.5 is the stronger model overall, scoring 60.5 to 24.9 on the Noometry Index.
Is Claude 2.1 or Claude Sonnet 5.5 better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 25.8 in the Noometry coding category.
How many benchmarks do Claude 2.1 and Claude Sonnet 5.5 share?
2 benchmarks have published results for both models. Claude 2.1 has 7 scored results on Noometry and Claude Sonnet 5.5 has 16.