Claude Sonnet 5.5 API pricing
Claude Sonnet 5.5 is a multimodal language model from Anthropic with a 1M-token context window. On FastInfra it costs $2.16 per million input tokens and $10.80 per million output tokens, billed per token from prepaid credit with no subscription. It supports tool calling, structured JSON output, adjustable reasoning and image input. It was released in September 2026. Call it as "anthropic/claude-sonnet-5.5" from any OpenAI SDK by changing the base URL and API key.
Prices synced November 3, 2026 · Model ID anthropic/claude-sonnet-5.5
Claude Sonnet 5.5 specs and pricing
Claude Sonnet 5.5 API pricing per token
You pay for prompt tokens at the input rate and generated tokens at the output rate. No subscription, seat fee or minimum — credit never expires.
| Rate | Input / 1M tokens | Output / 1M tokens | Input / 1K tokens |
|---|---|---|---|
| Standard (real-time) | $2.16 | $10.80 | $0.00216 |
Batch (async) · anthropic/claude-sonnet-5.5:batch |
$1.08 | $5.40 | $0.00108 |
What Claude Sonnet 5.5 costs in practice
Worked examples at the standard rate above. Real token counts depend on your prompts.
| Workload | Tokens | Cost |
|---|---|---|
| 1,000 chatbot replies | 1,500 input + 400 output tokens each | $7.56 |
| Summarise a 100-page report | ≈60,000 input + 1,500 output tokens | $0.15 |
| RAG answers over your docs, 10,000 queries | 4,000 input + 300 output tokens each | $119 |
| Coding-agent session | ≈250,000 input + 25,000 output tokens | $0.81 |
| 1M input + 1M output tokens | the per-million list rates combined | $12.96 |
Claude Sonnet 5.5 cost calculator
Enter your traffic to estimate daily and monthly spend at the live FastInfra rate.
How to call the Claude Sonnet 5.5 API
Works with the official OpenAI SDKs — change the base URL and API key only. One key covers every model on FastInfra.
| Field | Value |
|---|---|
| Model ID | anthropic/claude-sonnet-5.5 |
| Capability | Chat (vision) |
| Base URL | https://api.fastinfra.ai/v1 |
| Primary endpoint | POST https://api.fastinfra.ai/v1/chat/completions |
| Auth | Authorization: Bearer YOUR_API_KEY |
| OpenAI Chat SDK | Yes — set base_url to the Base URL |
| Validate model id | GET https://api.fastinfra.ai/v1/models/anthropic/claude-sonnet-5.5 |
| Docs | Integration reference |
Use multimodal message content (image_url). Same base URL as text chat.
Python
from openai import OpenAI
client = OpenAI(api_key="YOUR_API_KEY", base_url="https://api.fastinfra.ai/v1")
stream = client.chat.completions.create(
model="anthropic/claude-sonnet-5.5",
messages=[{"role": "user", "content": "Explain vector databases in two sentences."}],
stream=True,
)
for chunk in stream:
print(chunk.choices[0].delta.content or "", end="")Node.js
import OpenAI from "openai";
const client = new OpenAI({ apiKey: process.env.FASTINFRA_API_KEY, baseURL: "https://api.fastinfra.ai/v1" });
const response = await client.chat.completions.create({
model: "anthropic/claude-sonnet-5.5",
messages: [{ role: "user", content: "Hello!" }],
});
console.log(response.choices[0].message.content);curl
curl https://api.fastinfra.ai/v1/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "anthropic/claude-sonnet-5.5",
"messages": [{"role": "user", "content": "Hello!"}]
}'Served over 1 independent route. Requests go to the lowest-cost healthy route and fail over automatically if one is unavailable. Live latency and uptime are on the status page.
Claude Sonnet 5.5 vs alternatives
Live FastInfra prices per 1M tokens. Every model uses the same API key, so switching is a one-line change.
| Model | Input | Output | Context | |
|---|---|---|---|---|
| Claude Sonnet 5.5 (this page) | $2.16 | $10.80 | 1M | |
| Claude Opus 5 | $5.40 | $27.00 | 1M | Compare |
| Claude Sonnet 5 | $2.16 | $10.80 | 1M | Compare |
| Claude Haiku 5.5 | $0.11 | $0.54 | 1M | Compare |
| Claude Fable 5.1 | $10.80 | $54.00 | 1M | Compare |
| GPT-5.5 | $5.40 | $32.40 | 1.05M | Compare |
| Claude Haiku 4.5 | $1.08 | $5.40 | 200K | Compare |
| Claude Sonnet 4.5 | $3.24 | $16.20 | 1M | Compare |
Claude Sonnet 5.5 API — frequently asked questions
How much does the Claude Sonnet 5.5 API cost?
On FastInfra, Claude Sonnet 5.5 (anthropic/claude-sonnet-5.5) costs $2.16/1M input, $10.8/1M output tokens. Billing is per token used from prepaid credit, with no subscription or minimum spend.
What is the Claude Sonnet 5.5 context window?
Claude Sonnet 5.5 accepts up to 1,000,000 tokens of context (about 1M) and can generate up to 128,000 output tokens per response. Prompt and response tokens share that window.
Is there a cheaper batch price for Claude Sonnet 5.5?
Yes. The batch variant anthropic/claude-sonnet-5.5:batch costs $1.08/1M input and $5.4/1M output tokens for asynchronous jobs that do not need an immediate answer.
Is Claude Sonnet 5.5 compatible with the OpenAI SDK?
Yes. Point the OpenAI Python or Node SDK at https://api.fastinfra.ai/v1, use a FastInfra API key and set model to "anthropic/claude-sonnet-5.5". Chat completions, streaming, tool calling and JSON structured output use the same request shape.
Does Claude Sonnet 5.5 support tool calling and vision?
Claude Sonnet 5.5 supports tool (function) calling, JSON structured output, configurable reasoning and image input.
What is a cheaper alternative to Claude Sonnet 5.5?
Claude Haiku 5.5 costs $0.108/1M input and $0.54/1M output tokens on FastInfra. Both use the same API key, so switching is a one-line change to the model string.
Start using Claude Sonnet 5.5 today
Create a free account, add credit from $5 and make your first Claude Sonnet 5.5 request in under five minutes. Compare every model on the pricing page.