Claude Sonnet 4.5
Parameters
Undisclosed
Context Length
200K
Modality
Text
Architecture
Undisclosed
License
Proprietary
Release Date
29 Sept 2025
Knowledge Cutoff
Jan 2025
API Pricing (per 1M)
Input: $3.00 · Output: $15.00
Evaluation Benchmarks
Rank
#72
| Benchmark | Score | Rank |
|---|---|---|
Software Engineering | 0.75 | 8 |
StackUnseen | 0.694 | 18 |
General Text | high (32k) 1456 Standard 1455 | 50 55 |
Graduate-Level QA | 0.834 | 52 |
Web Development | high (32k) 1393 Standard 1385 | 69 73 |
Coding Index | 0.52 | 83 |
Agentic Index | 0.17 | 87 |
Intelligence Index | 0.19 | 138 |
Rankings
Overall Rank
#72
Coding Rank
#55
About Claude Sonnet 4.5
Claude Sonnet 4.5 is a production-grade multimodal model from Anthropic built for agentic execution, codebase refactoring, and parallel tool calling. It delivers fast, dependable reasoning with support for extended 1M token beta contexts.
Technical Specifications
Architecture specifications are undisclosed for proprietary models.
Attention
Attention Structure
Multi-Head Attention
Attention Heads
Undisclosed
Key-Value Heads
Undisclosed
Attention Head Dimension
Undisclosed
Position Embedding
Absolute Position Embedding
RoPE Theta
Undisclosed
Sliding Window Attention
Undisclosed
Sliding Window Size
Undisclosed
Sliding Window Ratio
Undisclosed
Linear Attention
Undisclosed
Linear Attention Ratio
Undisclosed
Normalization
Undisclosed
Activation Function
Undisclosed
Dimensions
Hidden Dimension Size
Undisclosed
Number of Layers
Undisclosed
FFN Intermediate Size (Dense)
Undisclosed
Multi-Token Prediction Heads
Undisclosed
Tokenizer
Vocabulary Size
Undisclosed
Resources
About Claude 4.5
Enhanced Claude models with further improvements in reasoning, coding, and agentic capabilities. Features advanced thinking modes with adjustable effort levels (high, medium, standard) for optimal performance-latency tradeoffs. Excels at complex analysis, software development, web development, and long-context understanding. Includes thinking variants that expose reasoning process for improved transparency.