Claude 3.5 SonnetvsClaude Sonnet 4.5
Claude 3.5 Sonnet | Claude Sonnet 4.5 | |
|---|---|---|
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 45% | 79%Best |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 33.4% | 77.2%Best |
Next.js coding Next.js EvalsVercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | — | 50% |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 59.4% | 83.4%Best |
Multimodal MMMUTests the AI on understanding images and text together across many college subjects. Higher is better. | — | 68% |
| Overview | ||
| Company | Anthropic | Anthropic |
| Release date | Jun 20 2024 | Sep 29 2025 |
| Access | Proprietary | Proprietary |
Which is better: Claude 3.5 Sonnet or Claude Sonnet 4.5?
Claude Sonnet 4.5 leads Claude 3.5 Sonnet on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Claude 3.5 Sonnet shipped 466 days before Claude Sonnet 4.5, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
On BullshitBench v2, Claude Sonnet 4.5 leads at 79% vs Claude 3.5 Sonnet at 45%. On SWE-Bench Verified, Claude Sonnet 4.5 leads at 77.2% vs Claude 3.5 Sonnet at 33.4%. On GPQA Diamond, Claude Sonnet 4.5 leads at 83.4% vs Claude 3.5 Sonnet at 59.4%.
Frequently asked questions
Claude 3.5 Sonnet was released by Anthropic on Jun 20 2024.
Claude Sonnet 4.5 was released by Anthropic on Sep 29 2025.
Claude Sonnet 4.5 leads on SWE-Bench Verified — Claude 3.5 Sonnet 33.4% vs Claude Sonnet 4.5 77.2%.
Claude Sonnet 4.5 leads on GPQA Diamond — Claude 3.5 Sonnet 59.4% vs Claude Sonnet 4.5 83.4%.