Claude Sonnet 5
Save 72%Officialanthropic/claude-sonnet-5
Anthropic's most agentic Sonnet — Opus-class capability at lower cost.
- Context window
- 1M
- Max output
- 8K
- Input modalities
- text · image
- Output modalities
- text
- Capabilities
- Vision · Reasoning · Tool calling · Coding · Prompt cache · Strip Sampling Params
- Upstream release
- 2026-06-30
- RouteMux name
- anthropic/claude-sonnet-5
Try Claude Sonnet 5 here
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What is Claude Sonnet 5
Claude Sonnet 5 is the model most production workloads should default to. Anthropic describes it as its most agentic Sonnet — it plans, uses tools and runs autonomously at a level that until recently needed a larger and more expensive model. It has the same 1M-token context window and native prompt caching as Opus 5.
Through RouteMux it is $0.56 per 1M input tokens against Anthropic's $2, and $2.80 against $10 on output — 40% of Opus 5's rate for the same context window and the same Messages API.
The useful way to think about the Claude lineup here is that context is not the variable: Fable, Opus and Sonnet all carry 1M. What changes is how much reasoning you are paying for. Start on Sonnet and move up only when a task fails for reasoning reasons rather than context reasons.
Claude Sonnet 5 API pricing
Source: anthropic_x0.28 · Verified 2026-08-17
Cache read $0.056/M · Cache write $0.7/M
Estimate cost
Limited time20% extra Credits on your first top-up — up to 200 bonus Credits
Applies to your first top-up within 72 hours of signing up. Minimum $20, once per account.
Key capabilities
Most agentic Sonnet
Anthropic positions it for planning, tool use and autonomous runs — the workloads that used to require an Opus-class model.
Same 1M context as Opus
Context is not what separates the Claude tiers; reasoning depth and price are.
Native prompt caching
Reused system prompts and long shared context are billed at the cache rate.
40% of Opus 5's token price
$0.56 vs $1.40 input, on the same API and the same context window.
Interface and protocols
Use any of these IDs to call this model via the API.
anthropic/claude-sonnet-5Replace the ROUTEMUX_KEY placeholder with your API key. Create one →
from anthropic import Anthropic
client = Anthropic(
base_url="https://api.routemux.com/anthropic",
api_key="<ROUTEMUX_KEY>",
)
message = client.messages.create(
model="anthropic/claude-sonnet-5",
max_tokens=1024,
messages=[{"role": "user", "content": "What is the meaning of life?"}],
)
print(message.content[0].text)Performance (last 30 days)
Claude Sonnet 5 FAQ
›What is Claude Sonnet 5?
Anthropic's most agentic Sonnet — Opus-class capability at lower cost.
›How large is the context window of Claude Sonnet 5?
Claude Sonnet 5 supports a context window of up to 1M tokens, with up to 8K output tokens per request.
›How much does the Claude Sonnet 5 API cost?
Through RouteMux, Claude Sonnet 5 costs $0.56 for input and $2.8 for output (USD per 1M tokens), below the official list price.
›How do I call Claude Sonnet 5 via API?
Claude Sonnet 5 is OpenAI-compatible: point your base URL at RouteMux and set the model field to anthropic/claude-sonnet-5 — no code changes needed.
›Which input and output modalities does Claude Sonnet 5 support?
Claude Sonnet 5 accepts text, image as input and produces text as output.
›When was Claude Sonnet 5 released?
Claude Sonnet 5 was released on June 30, 2026.
›When should I move from Sonnet 5 to Opus 5?
When a task fails for reasoning reasons. Both carry a 1M context, so 'ran out of room' is not the differentiator between them.
›Does it support vision and tool calling?
Yes — text and image input, tool calling, and native prompt caching.
Sources
Reviewed by Jerry Fan on 2026-08-17