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A tall flowing ribbon of terracotta clay and ivory paper curling upward in a gentle spiral on a dark background, abstract hero artwork for Claude Sonnet 5.5

Anthropic

Claude Sonnet 5.5

Anthropic's upgrade to Sonnet 5 for everyday building, bug fixing and polished documents.

Chat with Claude Sonnet 5.5 in Super AgentView pricing

What is Claude Sonnet 5.5?

Claude Sonnet 5.5 is Anthropic's Sonnet model for well-scoped everyday work, released on September 28, 2026.

Anthropic calls it a clear upgrade over Claude Sonnet 5: it runs more than 30% faster, costs up to 30% less per task, and is strongest at fixing bugs and producing polished documents, slides and spreadsheets. Anthropic's docs describe it as its best mix of speed and intelligence, and it writes more clearly than the previous generation. It reads text and images and holds 1M tokens of context. Super Agent keeps its thinking on, so effort is how you trade depth for speed.

Provider
Anthropic
Context window
1M tokens
Input
Text, Image
Reasoning
Low to max
Max output
128K tokens
Knowledge cutoff
June 2026
Released
Sep 28, 2026

How Claude Sonnet 5.5 performs

Published by Anthropic

Results Anthropic reported for Claude Sonnet 5.5. Each lab runs its own setup, so compare these with other models only inside the same table.

Benchmark results Anthropic published for Claude Sonnet 5.5
BenchmarkScoreSetting
Terminal-Bench 4.070.6%
FrontierCode 1.1 (Main)52.1%extra high effort
FrontierCode 1.1 (Main)46.2%max effort
CursorBench 4.055.5%
Humanity's Last Exam64.5%with tools
OSWorld 2.180.1%partial
Chartography61.6%no tools

Source: anthropic.com

What you can do with Claude Sonnet 5.5

  • More than 30% faster than Sonnet 5, according to Anthropic

  • Strong at polished documents, slides and spreadsheets

  • First Sonnet model to beat Pokémon Red working only from screenshots

  • 1M-token context window with image input

  • Effort from low to max

How to prompt Claude Sonnet 5.5

  • Keep each request well scoped. Sonnet 5.5 is tuned for clear everyday tasks more than open-ended research.
  • Leave effort on low for quick turns and raise it for planning a whole campaign.
  • Ask for the final copy in the format you need (a caption, a slide outline, a table) and it will follow it.

Where Claude Sonnet 5.5 fits best

  • Everyday creative chat and planning

  • Clear scripts, captions and briefs

  • Well-scoped agent tasks that should finish fast

  • Slides, spreadsheets and formatted documents

How Claude Sonnet 5.5 compares

Claude Sonnet 5.5 compared with other chat models on Flashloop
ModelLMArena textLMArena codingContext windowReasoning
Claude Sonnet 5.51478#291528#261M tokensLow to max
Gemini 3.5 Flash1477#301508#621M tokensLow, medium, high
GPT-6 Astra1477#321543#91.05M tokensLow to max
GPT-6.1 Sol1480#271537#141.05M tokensLow to max
GLM-5.31481#261521#331M tokensLow, medium, high, max

Good to know before you start

  • No thinking-off setting in Super Agent; Anthropic's API swaps Sonnet 5's off switch for one that skips only up-front thinking
  • Anthropic says Opus 5.5 stays clearly stronger at complex, open-ended work
  • Text output only, so the captions and shot lists it writes go to Flashloop's image and video models to become media

Start chatting with Claude Sonnet 5.5

Chat with Claude Sonnet 5.5 in Super Agent

  1. Select Claude Sonnet 5.5

    Open Super Agent on Flashloop and choose Claude Sonnet 5.5 in the model picker.

  2. Enter your prompt

    Ask for what you need: an answer, a plan, or the images and videos you want the agent to make.

  3. Send and keep going

    Send the message. Claude Sonnet 5.5 answers in Super Agent and runs any generations you asked for.

Questions about Claude Sonnet 5.5

How is Claude Sonnet 5.5 different from Claude Sonnet 5?

Anthropic says Sonnet 5.5 runs more than 30% faster, costs up to 30% less per task and is better at fixing bugs and making documents, slides and spreadsheets. In Super Agent, Sonnet 5 can run with thinking off and Sonnet 5.5 can't. On Anthropic's API, Sonnet 5.5 has a setting that skips up-front thinking in place of the off switch.

Should I pick Claude Sonnet 5.5 or Claude Opus 5.5?

Sonnet 5.5 suits well-scoped everyday work and quick turns. Anthropic says Opus 5.5 remains clearly stronger at complex, open-ended work that needs sustained judgment.

What context window does Claude Sonnet 5.5 have?

1M tokens, with text and image input.

What reasoning effort does Super Agent use for Claude Sonnet 5.5?

It starts at low. You can raise it to medium, high, extra high or max in the model picker.

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