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Claude Sonnet 4

Mid-2025 mid-tier Claude, the predecessor workhorse to Sonnet 4.6 and still common in production.

Updated

Quick facts

Released
May 2025
Context
200K tokens
Output / 1M
$15.00 / 1M tokens
License
Proprietary

About Claude Sonnet 4

Sonnet 4 was Anthropic's mid-tier launch alongside Opus 4 and the model that powered the bulk of Claude API traffic through the rest of 2025. Most production migrations to 4.6 happened over Q1 2026; many older deployments still run on 4 for stability.

Benchmarks

Published scores from Anthropic's model card or independent leaderboards. We do not publish numbers we cannot source, see methodology.

HumanEval
,
Python coding pass@1
MMLU
,
Broad academic knowledge
GPQA
,
Graduate-level reasoning
SWE-bench
65.0
Real software-engineering tasks
  • SWE-bench Verified65.0

Capabilities

Strengths

  • Solid all-rounder
  • Mature deployment ecosystem

Tracked weaknesses

  • Mostly superseded by 4.6

Pricing

Per-million-token rates as published by Anthropic.

TierPriceNotes
Input$3.00 / 1M tokensTokens you send to the model
Output$15.00 / 1M tokensTokens the model generates
Context200K tokensMax combined input + output

Call Claude Sonnet 4 from your code

Drop-in snippet for the Anthropic SDK. Set your API key in the environment and run.

typescript
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY,
});

const message = await client.messages.create({
  model: "claude-sonnet-4",
  max_tokens: 1024,
  messages: [
    { role: "user", content: "What's the time complexity of quicksort?" },
  ],
});

console.log(message.content);

Compare Claude Sonnet 4 with…

Frequently asked

  • How much does Claude Sonnet 4 cost per million tokens?
    Claude Sonnet 4 is priced at $3.00 / 1M tokens for input tokens and $15.00 / 1M tokens for output tokens via the official Anthropic API at the time of writing.
  • What is Claude Sonnet 4's context window?
    Claude Sonnet 4 supports a context window of 200K tokens.
  • Is Claude Sonnet 4 open source?
    No. Claude Sonnet 4 is a closed-weight model, you can use it via Anthropic's API but the model weights are not publicly downloadable.
  • When was Claude Sonnet 4 released?
    Claude Sonnet 4 was released on May 22, 2025 by Anthropic.
  • What is Claude Sonnet 4's knowledge cutoff?
    Claude Sonnet 4's training data has a knowledge cutoff of Mar 2025. For information after that date you'll need a tool-use or web-search wrapper.
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