Claude Sonnet 4.5

Anthropic

September 2025 upgrade to the Sonnet line with stronger coding and agentic performance and a 1M-token context window (beta). The balanced choice for most production workloads.

Strengths

Strong coding and agentic performance at Sonnet pricing
Extended thinking with 64K max output
Excellent intelligence-to-cost ratio for production use

Caveats

Superseded by Sonnet 4.6 (1M context, more recent training)
Knowledge cutoff trails Sonnet 4.6

Vendor: Anthropic
Context Window: 200,000 tokens
Max Output: 64,000 tokens
License: Proprietary
Release Date: 2025-09-29
Training Cutoff: 2025-07-31
Modalities: text
image

Capabilities

Vision

Audio

Video

Tool Use

Resources

API Documentation

Pricing

$3 per 1M input tokens, $15 per 1M output tokens. Prompt caching and Batch API (50% off) available.