Claude Sonnet 4.5 vs Claude Opus 5.5
Compare Claude Sonnet 4.5 and Claude Opus 5.5 side-by-side.
Compare Claude Sonnet 4.5 vs Claude Opus 5.5 live
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Models in this comparison
Claude Sonnet 4.5 vs Claude Opus 5.5 Comparison Table
Evals updated September 22, 2026Pricing updated September 22, 2026
| Property | Claude Sonnet 4.5 | Claude Opus 5.5 |
|---|---|---|
| Organization | Anthropic | Anthropic |
| Category | closed | closed |
| Modality | multimodal | multimodal |
| Release Date | Sep 2025 | Sep 2026 |
| Context Window | 200K | 1.0M |
| Parameters | ||
| License | Proprietary | Proprietary |
| Pricing per 1M tokens | ||
| Input $/1M | $3.00 | $4.00 |
| Output $/1M | $15.00 | $20.00 |
| Vision Tasks | ||
| Captioning | Demo | |
| Chart Question Answering | ||
| Classification | Demo | |
| Document Question Answering | ||
| Image Tagging | ||
| Multi-Label Classification | ||
| Object Detection | Demo | |
| OCR | Demo | |
| Vision Language | ||
| Visual Question Answering | Demo | |
| Model Features | ||
| Foundation Vision | ||
| LLMs with Vision Capabilities | ||
| Multimodal Vision | ||
Vision Evalsground-truth scores across 6 vision tasks, pooled at low effort | ||
| Overall | Not evaluated | 85.5% |
| Avg cost / sample | – | $0.014 |
| Avg speed / sample | – | 12.76s |
| By task | ||
| Object Detection (low) | – | 74.4% ±0.5, Mean of 3 runs, range 73.9 to 74.8 |
| Object Detection (high) | – | 76.8% ±1.2, Mean of 3 runs, range 75.4 to 77.8 |
| Counting (low) | – | 80.6% ±2.0, Mean of 3 runs, range 78.4 to 82.4 |
| Counting (high) | – | 82.0% ±2.0, Mean of 3 runs, range 79.7 to 83.8 |
| Identification (low) | – | 93.8% ±0.0, Mean of 3 runs, range 93.8 to 93.8 |
| Identification (high) | – | 95.8% ±1.6, Mean of 3 runs, range 93.8 to 96.9 |
| OCR (low) | – | 87.8% ±0.6, Mean of 3 runs, range 87.0 to 88.2 |
| OCR (high) | – | 87.2% ±0.6, Mean of 3 runs, range 86.5 to 87.8 |
| Data Extraction (low) | – | 93.5% ±0.5, Mean of 3 runs, range 92.8 to 93.8 |
| Data Extraction (high) | – | 93.5% ±0.5, Mean of 3 runs, range 92.8 to 93.8 |
| Reasoning (low) | – | 83.0% ±1.0, Mean of 3 runs, range 82.1 to 84.1 |
| Reasoning (high) | – | 85.9% ±2.6, Mean of 3 runs, range 82.8 to 88.1 |
Claude Sonnet 4.5 vs Claude Opus 5.5: Overview
Claude Sonnet 4.5, released by Anthropic in September 2025, is the company’s most advanced Sonnet-series model, built for high-performance reasoning, coding, and long-horizon agentic workflows. It is a multimodal system that accepts both text and images, with a 200,000-token context window designed for handling large documents and extended interactions. Anthropic highlights its improvements in reliability, reduced sycophancy, and alignment, making it suitable for sustained enterprise use.
The model delivers strong results in coding and autonomous workflows, achieving 61.4% on the OSWorld benchmark and leading performance on SWE-bench Verified. It introduces infrastructure features such as a memory tool (beta), checkpointing for Claude Code, parallel tool use, and tighter integration with VS Code. Compared to Opus, which targets broader reasoning, Sonnet 4.5 is optimized for structured, long-duration tasks. Positioned against leading offerings from OpenAI and Google, it is aimed at enterprise automation, software engineering, and research-intensive applications.
Claude Opus 5.5 is a proprietary multimodal reasoning model from Anthropic and the first entry in the Claude 5.5 family. It accepts interleaved text and image input and returns text, with a one million token context window and up to 128,000 output tokens per response. Adaptive thinking is always enabled on this model and cannot be disabled; thinking depth is instead governed by an effort parameter with five levels, where medium is the default, a change from the high default used by Claude Opus 5 and earlier Opus models. Anthropic reports a knowledge cutoff of June 2026.
On the visual side, Anthropic characterizes Opus 5.5 as its strongest Opus release for vision and computer use, describing improved reading of dense documents, charts, screenshots, and diagrams for document extraction and visual analysis tasks. Published results include 89.0% on Chartography with tools and 81.8% on OSWorld 2.0 under partial credit scoring, alongside 48.7% under strict scoring reported in the system card. The accompanying system card states that Opus 5.5 scored higher than Opus 5 on every evaluation in its capability summary, with the largest gains concentrated in agentic coding, visual reasoning, computer use, and long-horizon knowledge work. The model ships with safety classifiers covering biology and cybersecurity that can route blocked requests to earlier Claude models.