Claude Sonnet 4.5

anthropic/claude-4.5-sonnet-20250929

Claude Sonnet 4.5, released on 2025‑09‑29 by Anthropic, accepts text, image, and file inputs and produces text output. It supports tool usage and reasoning, and operates with a context window of up to 1,000,000 tokens. Pricing is 3 units per 1 M input tokens and 15 units per 1 M output tokens; the model’s weights are

  • tool use
  • structured outputs
  • reasoning

At a glance

provideranthropic
releasedSep 29, 2025
context1M
input / M$3

Specifications

What the API gives you

Context window
1M tokens
Max output
64K tokens
Input price
$3 / 1M tokens
Output price
$15 / 1M tokens
Cache read
$0.30 / 1M tokens
Modalities
text, image, file → text
Knowledge cutoff
Jan 31, 2025
Released
Sep 29, 2025

Recommendation coverage

Where this model appears

  1. #5Best LLM for Debugging & Code Review
  2. #7Best LLM for Agentic Coding

Measured evidence

Public benchmark record

LMArena Text
1438 Elo2026-07-16
LMArena WebDev
1386 Elo2026-07-16
LMArena WebDev
1386 Elo2026-07-20
SWE-bench Verified†
74.8%2025-11-03

LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. † Self-reported scaffold plus model result. Treat it as a claim, not an independent measurement.

Catalog data via OpenRouter and models.dev. Last checked within the past 6 hours.