Claude Sonnet 4vsClaude Sonnet 4.5
Claude Sonnet 4 | 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. | 30% | 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. | 72.7% | 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. | 75.4% | 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 | May 22 2025 | Sep 29 2025 |
| Access | Proprietary | Proprietary |
Which is better: Claude Sonnet 4 or Claude Sonnet 4.5?
Claude Sonnet 4.5 leads Claude Sonnet 4 on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Claude Sonnet 4 shipped 130 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 Sonnet 4 at 30%. On SWE-Bench Verified, Claude Sonnet 4.5 leads at 77.2% vs Claude Sonnet 4 at 72.7%. On GPQA Diamond, Claude Sonnet 4.5 leads at 83.4% vs Claude Sonnet 4 at 75.4%.
Frequently asked questions
Claude Sonnet 4 was released by Anthropic on May 22 2025.
Claude Sonnet 4.5 was released by Anthropic on Sep 29 2025.
Claude Sonnet 4.5 leads on SWE-Bench Verified — Claude Sonnet 4 72.7% vs Claude Sonnet 4.5 77.2%.
Claude Sonnet 4.5 leads on GPQA Diamond — Claude Sonnet 4 75.4% vs Claude Sonnet 4.5 83.4%.