Claude 4.5 Sonnet Thinking API

Claude 4.5 Sonnet offers a balance of intelligence and speed for diverse enterprise and coding tasks.

Modalities
TextText
In / Out price
$3/$15per 1M
Context window
200K tokens
Released
Oct 1, 2025

Claude 4.5 Sonnet Thinking overview

The pelican test: one prompt, every text model, unedited SVG output from Nov 3, 2026.

SVG of a pelican riding a bicycle, written by Claude 4.5 Sonnet Thinking through AI/ML API

Claude 4.5 Sonnet Thinking specs

Model ID
anthropic/claude-sonnet-4.5
Developer
Anthropic
Context window
200,000 tokens
Max output
64,000 tokens
Input
Text
Output
Text
API
OpenAI-compatible, base URL https://api.aimlapi.com/v1

What is Claude 4.5 Sonnet API?

Claude 4.5 Sonnet offers a balance of intelligence and speed for diverse enterprise and coding tasks.

Where to Use Claude 4.5 Sonnet

Coding and code review
Generate, debug, and review code across languages, reading whole files or repos in a single prompt.

Use cases

  • Programming assistance: code generation, debugging, review
  • Autonomous agent management for software tools and workflows
  • Financial and cybersecurity data analysis and automation
  • Research data synthesis and multi-agent coordination
  • Editing and generating documents, spreadsheets, presentations within conversations

Capabilities

  • Streaming

Claude 4.5 Sonnet Thinking benchmarks by Artificial Analysis

See how Claude 4.5 Sonnet Thinking compares in generation speed and latency. Data retrieved Nov 4, 2026.

Speed

Output tokens / second

Benchmark results

Compare 8 models available on AI/ML API across 5 independent benchmarks.

Humanity's Last Exam

Expert-written questions across academic subjects.

Claude 4.5 Sonnet Thinking API pricing

Claude 4.5 Sonnet Thinking pricing in US dollars
UsagePriceUnit
Input$31M tokens
Output$151M tokens
Cached input$0.31741M tokens

Prices from the AI/ML API price list, checked on Nov 4, 2026.

Claude 4.5 Sonnet Thinking vs other models: token prices

AI/ML API input and output rates for 5 models, per million tokens.

AI/ML API model prices in USD per million tokens
ModelInputOutput
Claude 4.5 Sonnet Thinking$3$15
Claude Haiku 5.5$0.1$0.5
Claude Sonnet 5.5$2$10
Claude Opus 5.5$4$20
Claude Fable 5.1$10$50

How to use the Claude 4.5 Sonnet Thinking API

View docs

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key
export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "anthropic/claude-sonnet-4.5",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

Related articles

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Claude 4.5 Sonnet Thinking FAQ

What is the context window of Claude 4.5 Sonnet Thinking?

Claude 4.5 Sonnet Thinking has a 200,000 tokens context window and can return up to 64,000 tokens.

What inputs and outputs does Claude 4.5 Sonnet Thinking support?

Claude 4.5 Sonnet Thinking takes text as input and returns text.

What is the model ID for Claude 4.5 Sonnet Thinking?

Use anthropic/claude-sonnet-4.5 as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

How much does Claude 4.5 Sonnet Thinking cost?

Claude 4.5 Sonnet Thinking costs $3 input and $15 output per 1M tokens on AI/ML API, billed as you go with no subscription.

Does Claude 4.5 Sonnet Thinking support streaming?

Yes, Claude 4.5 Sonnet Thinking can stream responses as they are generated.

Who created Claude 4.5 Sonnet Thinking?

Claude 4.5 Sonnet Thinking was built by Anthropic.

Is Claude 4.5 Sonnet Thinking a reasoning-focused model?

Its name includes 'Thinking,' indicating it is built for extended reasoning tasks.

Start building with Claude 4.5 Sonnet Thinking

Claude 4.5 Sonnet Thinking API

anthropic/claude-sonnet-4.5

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key
export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "anthropic/claude-sonnet-4.5",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'