Claude Sonnet 4.5 vs Claude Fable 5.2
Claude Fable 5.2: 86.5% average across five Vision Evals tasks (#2 of 67 models). We have not run Claude Sonnet 4.5 through Roboflow's Vision Evals, so there is no head-to-head score.
Compare Claude Sonnet 4.5 vs Claude Fable 5.2 live
Run the same image across every model that supports a task and compare their outputs side-by-side.
These models don't share enough common tasks for a side-by-side demo. See the comparison table below for their capabilities.
Claude Sonnet 4.5 vs Claude Fable 5.2 Comparison Table
Evals updated November 10, 2026Pricing updated November 10, 2026
| Property | Claude Sonnet 4.5 | Claude Fable 5.2 |
|---|---|---|
| Organization | Anthropic | Anthropic |
| Category | closed | closed |
| Modality | multimodal | multimodal |
| Release Date | Sep 2025 | Nov 2026 |
| Context Window | 200K | 1.0M |
| Parameters | Unknown | Unknown |
| License | Proprietary | Proprietary |
| Commercial use | commercial use per vendor terms | commercial use per vendor terms |
| Pricing per 1M tokens | ||
| Input $/1M | $3.00 | $8.00 |
| Output $/1M | $15.00 | $40.00 |
| Vision Tasks | ||
| Captioning | Demo | Supported |
| Classification | Demo | Supported |
| Object Detection | Demo | Supported |
| OCR | Demo | Supported |
| Visual Question Answering | Demo | Supported |
| Model Features | ||
Both support 3 more features | ||
Vision Evalsground-truth scores across 5 vision tasks, pooled at low effort | ||
| Overall | Not evaluated | 86.5% |
| Avg cost / sample | – | $0.031 |
| Avg speed / sample | – | 9.33s |
| By task | ||
| Object Detection (low) | – | 81.6% ±0.3, Mean of 3 runs, range 81.2 to 81.9 |
| Object Detection (high) | – | 83.3% ±0.5, Mean of 3 runs, range 82.8 to 83.7 |
| Counting (low) | – | 86.5% ±0.0, Mean of 3 runs, range 86.5 to 86.5 |
| Counting (high) | – | 92.8% ±1.4, Mean of 3 runs, range 91.9 to 94.6 |
| Identification (low) | – | 96.9% ±0.0, Mean of 3 runs, range 96.9 to 96.9 |
| Identification (high) | – | 94.8% ±1.6, Mean of 3 runs, range 93.8 to 96.9 |
| OCR (low) | – | 79.5% |
| by category |
| |
| OCR (high) | – | 84.8% |
| by category |
| |
| Reasoning (low) | – | 88.1% ±1.3, Mean of 3 runs, range 86.8 to 89.4 |
| Reasoning (high) | – | 92.0% ±1.0, Mean of 3 runs, range 91.4 to 93.4 |
Claude Sonnet 4.5 vs Claude Fable 5.2: 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.
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 Fable 5.2 is a proprietary multimodal model from Anthropic, released on November 9, 2026. It accepts text and images and produces text, with a one million token context window and up to 128,000 output tokens. Adaptive thinking is always enabled, with an effort setting that controls reasoning. Anthropic positions Fable for demanding reasoning and long-running technical work, including coding and analysis of visual inputs.
Fable 5.2 succeeds Fable 5.1. Anthropic reports improvements in coding, reasoning, and vision, with output generation up to 30% faster than its predecessor. Fable and Mythos 5.2 share an underlying model, with additional cybersecurity and biology safeguards applied to Fable. Model weights are not publicly released.