Claude Sonnet 5.5
Chat model · Anthropic ·
Claude Sonnet 5.5 is a chat model by Anthropic. In Endless it costs 243 credits per 1M input tokens and 1215 per 1M output tokens, on every plan.
Claude Sonnet 5.5 is Anthropic's fast everyday model for building features, fixing bugs and writing polished documents, slides and spreadsheets.
- Price
- 243 credits per 1M input tokens
- 1215 credits per 1M output tokens
- Availability
- Available on every plan
- Context window
- 1M tokens
- Max output
- 128K tokens
- Inputs
- Text, images
- Outputs
- Text
About Claude Sonnet 5.5
Claude Sonnet 5.5, released in September 2026, is the current Sonnet and the best balance of speed and intelligence in the Claude lineup. It generates output more than 30% faster than Claude Sonnet 5 and usually needs far fewer tokens for the same job. It takes text and images, holds 1M tokens of context and writes up to 128K tokens per reply.
It picks up a codebase quickly and batches its tool calls, so tasks finish in fewer steps. Use it for well-scoped features, bug fixes and multi-hour coding sessions. It also has a sharp eye for design when it creates documents, slides and spreadsheets, and its first drafts of reports and decks often need only light edits before they go out.
Claude Opus 5.5 scores close to Sonnet 5.5 on several tests but stays stronger at open-ended work that needs sustained judgment. Claude Haiku 5.5 is quicker for narrow, high-volume jobs. Sonnet 5.5 sits between them for daily work, and you can move between all three in the same Endless workspace.
Best for
- Shipping well-scoped features and bug fixes
- First drafts of reports, slide decks and spreadsheets
- Agent workflows where speed and step count matter
- Customer support flows that need quick, clear answers
Questions about Claude Sonnet 5.5
- What is Claude Sonnet 5.5?
- Claude Sonnet 5.5 is a chat model by Anthropic.
- Is Claude Sonnet 5.5 free?
- You can try Claude Sonnet 5.5 for free. It is on every Endless plan, including Free, which gives you 100 credits when you create a workspace and 50 credits every week. Each run spends credits from that balance.
- How much does Claude Sonnet 5.5 cost?
- In Endless it costs 243 credits per 1M input tokens and 1215 per 1M output tokens, on every plan.
- How do I use Claude Sonnet 5.5?
- Start a chat in your Endless workspace and choose Claude Sonnet 5.5 in the model picker. Endless can also pick the best model for each message on its own.
- What are the alternatives to Claude Sonnet 5.5?
- Similar models you can use in Endless include Claude Opus 5.5, Claude Fable 5, and Claude Fable 5.1. Each one has its own page with its price and plan.
- What is the difference between Claude Sonnet 5.5 and Claude Opus 5.5?
- They score close on several benchmarks, but Opus 5.5 is clearly stronger at complex, open-ended work that needs sustained judgment. Sonnet 5.5 is faster and suits well-scoped everyday tasks.
- Is Claude Sonnet 5.5 faster than Claude Sonnet 5?
- Yes. It generates output more than 30% faster than Sonnet 5 and usually completes the same work with fewer tokens.
- Can Claude Sonnet 5.5 make slides and spreadsheets?
- It writes the content and structure for documents, slides and spreadsheets with a good sense of layout. In chat it answers in text, so you get the draft to paste or refine.
How to use Claude Sonnet 5.5 in Endless
- 01
Open a chat
Start a chat in your workspace and choose Claude Sonnet 5.5 in the model picker.
- 02
Bring your context
Attach files, mention a project with @, or ask it to search the web and social media.
- 03
Turn answers into work
Generate images and video, write documents and save what matters to a project.
Related models
Claude Opus 5.5
by Anthropic
Long agentic coding and research work over a 1M-token context
324 / 1620 credits per 1M tokens
Claude Fable 5
by Anthropic
Long autonomous sessions that stay focused across millions of tokens
810 / 4050 credits per 1M tokens
Claude Fable 5.1
by Anthropic
Hard reasoning and long unattended agent runs over a 1M-token context
810 / 4050 credits per 1M tokens
Give your next idea a place to grow.
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