Claude Sonnet 4.5Anthropic

Using Claude for Summarization

Claude Sonnet 4.5's massive context window and precise instruction following make it the standout model for summarization tasks in 2026. From legal briefs to research papers to meeting transcripts, here is how to get the most out of it.

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Our verdict
9/10

Claude Sonnet 4.5 is the best model for summarization in 2026, and it is not particularly close. Its 200K-token context window means it can process entire books, legal filings, and multi-hour transcripts in a single pass without chunking. It produces faithful, well-structured summaries that capture key points without hallucinating details that were not in the source material. For shorter documents where speed matters more, Gemini 3 Flash is a fast and affordable alternative.

Where Claude Sonnet 4.5 excels at summarization

1No Chunking Required for Long Documents

Most models force you to split long documents into chunks and summarize each separately, losing cross-section context. Claude processes up to 200K tokens in one pass, producing a coherent summary that captures themes spanning the entire document.

2High Faithfulness, Low Hallucination

Claude is among the least likely models to introduce facts that were not in the source text. It sticks closely to the original material, which is critical for legal, medical, and financial summarization where accuracy is non-negotiable.

3Flexible Summary Formats

Claude can produce executive summaries, bullet-point lists, structured outlines, one-paragraph abstracts, or any custom format you specify. It adapts length and detail level precisely to your instructions.

4Handles Technical and Domain-Specific Content

Claude maintains technical accuracy when summarizing scientific papers, legal documents, financial reports, and medical literature. It preserves domain-specific terminology and does not over-simplify specialized concepts unless asked to.

Limitations to consider

!
Slower Than Lightweight Models

For quick summaries of short documents, Claude's processing time is overkill. Gemini 3 Flash can summarize a one-page email in a fraction of the time and at a fraction of the cost.

!
Can Be Overly Thorough

When asked to summarize, Claude sometimes includes more detail than necessary, producing a summary that is longer than you wanted. Be explicit about your desired length, such as 'summarize in exactly 3 bullet points.'

Pro tips

Get more from Claude Sonnet 4.5 for summarization

01

Always specify the desired output format and length: 'Summarize this 50-page report in 5 bullet points, each under 30 words.'

02

For multi-document summarization, paste all documents into a single prompt and ask Claude to identify common themes and contradictions across them.

03

Ask Claude to produce a layered summary: a one-sentence TL;DR, a one-paragraph executive summary, and a detailed bullet-point breakdown. This gives stakeholders at different levels what they need.

04

Use LLMWise Compare mode to test Claude and Gemini 3 Flash on the same summarization task. Use Claude for high-stakes documents and Gemini for routine summaries to optimize cost.

05

For meeting transcripts, ask Claude to extract action items, decisions made, and open questions in addition to a narrative summary.

Evidence snapshot

Claude Sonnet 4.5 for summarization

How Claude Sonnet 4.5 stacks up for summarization workloads based on practical evaluation.

Overall rating
9/10
for summarization tasks
Strengths
4
key advantages identified
Limitations
2
trade-offs to consider
Alternative
Gemini 3 Flash
top competing model
Consider instead

Gemini 3 Flash

Compare both models for summarization on LLMWise

View Gemini 3 Flash

Common questions

Can Claude summarize an entire book?
Yes. Claude Sonnet 4.5's 200K-token context window can hold most books in a single prompt. It produces a coherent summary that captures themes, character arcs, and key arguments across the full text without the context loss that comes from chunk-based summarization.
Is Claude accurate when summarizing legal documents?
Claude is one of the most faithful summarization models available, meaning it rarely introduces information that was not in the source. For legal documents, it preserves precise language and key clauses. However, always have a qualified professional review AI-generated legal summaries before relying on them.
How does Claude compare to Gemini for summarization?
Claude Sonnet 4.5 produces more thorough and faithful summaries, especially for long or complex documents. Gemini 3 Flash is significantly faster and cheaper, making it better for high-volume summarization of shorter texts. LLMWise lets you route to either model based on document length.
Can Claude summarize documents in other languages?
Yes. Claude Sonnet 4.5 can summarize documents in dozens of languages and can even produce a summary in a different language than the source. For example, you can feed it a French legal document and ask for an English summary.
How much does Claude Sonnet 4.5 API cost for summarization?
Claude is premium-priced per token, but its ability to process long documents in a single pass can reduce total costs compared to chunked approaches. LLMWise credits offer predictable pricing, and you can use Gemini 3 Flash for routine summaries to save.
Can I use Claude for summarization with LLMWise?
Yes. LLMWise gives you API access to Claude Sonnet 4.5 for summarization with built-in failover and model routing. You can use Auto mode to send short documents to faster models and long documents to Claude automatically.

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