Anthropic
Claude Sonnet 4.5
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows.
At a glance
- Input / 1M
- $3
- Output / 1M
- $15
- Context
- 1M
- Max output
- 64K
- Intelligence
- 20.7
- Released
- Sep 2025
Pricing
Claude Sonnet 4.5 API pricing
Per-token rates, plus what common tasks actually cost.
| Input tokensPer 1M tokens | $3 |
|---|---|
| Output tokensPer 1M tokens | $15 |
| Cached input (read)Per 1M tokens | $0.30 |
| Cache writePer 1M tokens | $3.75 |
| Long-context pricingPrompts above 200K tokens | $6 in / $22.50 out |
| Web searchPer request | $0.01 |
Chat message
2K in, 500 out
$13.50
per 1,000 requests
Coding task
30K in, 4K out
$150
per 1,000 requests
Long document summary
150K in, 2K out
$480
per 1,000 requests
Benchmarks
Claude Sonnet 4.5 benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
20.7
Coding index
52.1
Agentic index
15.8
Specs
Context window and capabilities
What it can read, what it can write, and which API features it supports.
- Context window
- 1M tokens
- Max output
- 64K tokens
- Input types
- File, Image, Text
- Output types
- Text
- Reasoning effort
- Not available
- Release date
- September 29, 2025
- Knowledge cutoff
- January 31, 2025
- Tool calling
- Structured outputs
- JSON mode
- Reasoning
- Temperature
- Stop sequences
- Deterministic seed
- Verbosity control
Compare
Claude Sonnet 4.5 vs other models
See how Claude Sonnet 4.5 stacks up head to head on price, benchmarks, and features.
VSClaude Sonnet 4.5 vs Claude Sonnet 4.6
Anthropic vs Anthropic
See comparisonVSClaude Sonnet 4.5 vs Claude Haiku 4.5
Anthropic vs Anthropic
See comparisonVSClaude Sonnet 4.5 vs Claude Opus 4.5
Anthropic vs Anthropic
See comparisonVS
Claude Sonnet 4.5 vs GPT-5.1
Anthropic vs OpenAI
See comparisonVSClaude Sonnet 4.5 vs GPT-5.1-Codex
Anthropic vs OpenAI
See comparisonVS
Claude Sonnet 4.5 vs Gemini 2.5 Pro
Anthropic vs Google
See comparisonAlternatives
Claude Sonnet 4.5 alternatives
Similar models worth considering, and where each one has the edge.
Anthropic
Claude Sonnet 4.6
OpenAI
GPT-5.1
OpenAI
GPT-5.1-Codex
Want to learn about other models? Browse all models
FAQ
Frequently asked questions
How much does Claude Sonnet 4.5 cost?
Claude Sonnet 4.5 costs $3 per 1M input tokens and $15 per 1M output tokens through the API. A typical chat message costs about $13.50 per 1,000 messages.
What is the context window of Claude Sonnet 4.5?
Claude Sonnet 4.5 accepts up to 1M tokens of input and can write up to 64K tokens in a single response.
What is the best alternative to Claude Sonnet 4.5?
Claude Sonnet 4.6 from Anthropic is a strong alternative. It offers: higher intelligence score, newer release.
Can I use Claude Sonnet 4.5 alongside other models?
Yes. Shortcut Chat sends one prompt to Claude Sonnet 4.5 and any other models you pick at the same time, so you can compare answers side by side.
Try Claude Sonnet 4.5 next to every other model.
Use Claude Sonnet 4.5 alongside all the other models. Use one at a time, or multiple together. Get the best answer from every AI.