Claude Sonnet 5.5
Faster, cheaper mid-tier model for everyday tasks and agentic work
Context window
1M
Input / 1M tokens
$2.00
Output / 1M tokens
$10.00
Provider
Anthropic
Data verified 2026-09-29
Claude Sonnet 5.5 is Anthropic's mid-tier model designed for everyday tasks, coding, and document production. It runs 30% faster than Sonnet 5 while maintaining the same list price. The model scores nearly as well as Opus 5.5 on many benchmarks while offering better speed and cost efficiency for well-scoped work.
Capability index
Relative estimates (0-100) to place this model against its peers, grounded in published benchmarks.
How to access it
Available via Anthropic Claude API, Amazon Web Services, Google Cloud, and Microsoft Azure with standard API access.
Strengths
- ✓30% faster execution than Sonnet 5
- ✓Strong agentic coding performance
- ✓Excellent at document generation and formatting
- ✓Design-oriented capabilities
- ✓Same price as Sonnet 5
Best for developers who...
When to choose it (and when not to)
Reach for Claude Sonnet 5.5 when...
- →Need faster responses than Sonnet 5
- →Working with well-scoped tasks
- →Cost-conscious deployment at scale
- →Agentic applications
Look elsewhere if...
- ✕Complex reasoning requiring sustained judgment
- ✕Open-ended problems needing careful analysis
- ✕Tasks where Opus 5.5 is necessary
How to use it
- ›Use between_tools setting for production deployments
- ›Structure prompts around well-defined task boundaries
- ›Leverage its speed for high-volume agentic loops
Quickstart
Pythonfrom anthropic import Anthropic
client = Anthropic()
message = client.messages.create(
model="claude-sonnet-5-5",
max_tokens=1024,
messages=[{"role": "user", "content": "Hello!"}]
)
print(message.content[0].text)Use model ID 'claude-sonnet-5-5' with Anthropic SDK
API model id: claude-sonnet-5-5
Benchmarks
| Benchmark | Score | Notes |
|---|---|---|
| Terminal-Bench 4.0 (Agentic Coding) | 70.6% | Significant improvement over Sonnet 5's 10.3% |
| CursorBench 4.0 | 55.5% | vs 34.1% for Sonnet 5 |
| GDPval-AA v2.1 (Knowledge Work) | 1844 Elo | Two points behind Opus 5.5's 1846 |
Source: Anthropic official announcement
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