Anthropic: Claude Sonnet 4.5✓ Catalog verified
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with...
Overview
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with...
Access: available through the official Anthropic API. Context window: 1M.
Specifications
| API identifier | anthropic/claude-sonnet-4.5 |
| Provider | Anthropic |
| Model type | Multimodal LLM |
| Context window | 1M catalog |
| Input modalities | text · image · file |
| Output modalities | text |
| Released | Sep 29, 2025 |
| Tokenizer | Claude |
| Moderated | Yes |
| Architecture modality | text+image+file->text |
API defaults
{
"top_k": null,
"top_p": 1,
"temperature": 1,
"presence_penalty": null,
"frequency_penalty": null,
"repetition_penalty": null
}Pricing
Live pricing components for anthropic/claude-sonnet-4.5 as published in the catalog.
| Pricing component | Raw unit price | Normalized | Unit |
|---|---|---|---|
| Prompt tokens | $0.000003 | $3.00 / 1M | Per input token |
| Completion tokens | $0.000015 | $15.00 / 1M | Per output token |
| Request fee | N/A | N/A | Per request |
| Image fee | N/A | N/A | Per image unit |
| Web search fee | $0.01 | $0.010000 | Per search request |
Cost calculator
Estimate monthly spend from your own token volumes.
Estimated Total Cost
$4.5Calculated from current list pricing in the ModelsAtlas catalog.Capabilities
| Capability | Status | What it means |
|---|---|---|
| Visual Understanding | ✓ Supported | Image and document analysis support |
| Audio Processing | Not advertised | Speech and voice aligned flows |
| Tool Calling | ✓ Supported | Supports tools / function calling |
| Self-Hosting | Not advertised | Deploy outside managed APIs |
Capability signals
Directional signals derived from model metadata and capability tags — not official benchmark submissions.
Quick start
Call Anthropic: Claude Sonnet 4.5 through an OpenAI-compatible client.
from openai import OpenAI
client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key="YOUR_API_KEY"
)
response = client.chat.completions.create(
model="anthropic/claude-sonnet-4.5",
messages=[{"role": "user", "content": "Explain quantum physics."}]
)
print(response.choices[0].message.content)Alternatives
Closest models by context window from a different provider.
| Model | Provider | Context | Input /1M | Actions |
|---|---|---|---|---|
| Amazon: Nova 2 Lite | Amazon | 1M | $0.30 | View → |
| Amazon: Nova Premier 1.0 | Amazon | 1M | $2.50 | View → |
Head-to-head comparisons
Side-by-side breakdowns of Anthropic: Claude Sonnet 4.5 against other frontier models.
Sources & attribution
Pricing and metadata are maintained in the ModelsAtlas catalog.
Frequently asked questions
How much does Anthropic: Claude Sonnet 4.5 cost?
$3.00 per 1M input tokens and $15.00 per 1M output tokens on the official Anthropic API.
What is the context window of Anthropic: Claude Sonnet 4.5?
Anthropic: Claude Sonnet 4.5 supports up to 1M tokens of context.
Does Anthropic: Claude Sonnet 4.5 support tool / function calling?
Yes, Anthropic: Claude Sonnet 4.5 supports tool / function calling — you can register tools and the model will emit structured tool calls.
How do I access Anthropic: Claude Sonnet 4.5?
Use the official Anthropic API with the model id `anthropic/claude-sonnet-4.5`. See the Quick start section above for code examples.