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Claude Sonnet 5.5 vs LongCat-Flash-Chat

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 19.8. LongCat-Flash-Chat is 7.6x cheaper per token.

Anthropic · Meituan · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 19.8, ranking #3 overall.

On price, LongCat-Flash-Chat is roughly 7.6x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Claude Sonnet 5.5 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 5.5

  • overall performance matters — it scores 58.0 and ranks #3 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you process long inputs — it offers a 1,000,000 token context window
  • you want the most recent training data — it shipped Sep 2026

Choose LongCat-Flash-Chat

  • cost matters — it's about 7.6x cheaper per token
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
LongCat-Flash-Chat
Meituan
Core performance indexes
LLM Stats Score
58.0
#3
19.8
#206
Reasoning
56.6
#3
19.8
#202
Coding
48.8
#2
12.4
#154
Agents
42.3
#3
9.1
#134
Cost, coverage & limits
Benchmark wins
—
—
Input price
$2.00 / M
$0.30 / M
Output price
$10.00 / M
$1.20 / M
Context window
1,000,000
128,000

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Claude Sonnet 5.5
LongCat-Flash-Chat
Math
36.9#34
18.9#176
Tool use
34.0#2
8.5#143
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 16 for LongCat-Flash-Chat

No common benchmarks found

Claude Sonnet 5.5 and LongCat-Flash-Chatdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

LongCat-Flash-Chat costs less

For input processing, Claude Sonnet 5.5 ($2.00/1M tokens) is 6.7x more expensive than LongCat-Flash-Chat ($0.30/1M tokens).

For output processing, Claude Sonnet 5.5 ($10.00/1M tokens) is 8.3x more expensive than LongCat-Flash-Chat ($1.20/1M tokens).

In conclusion, Claude Sonnet 5.5 is more expensive than LongCat-Flash-Chat.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Mon Oct 05 2026 • llm-stats.com
Anthropic
Claude Sonnet 5.5
Input tokens$2.00
Output tokens$10.00
Best providerAnthropic
Meituan
LongCat-Flash-Chat
Input tokens$0.30
Output tokens$1.20
Best providerMeituan
Notice missing or incorrect data?

Context Window

Maximum input and output token capacity

Claude Sonnet 5.5 accepts 1,000,000 input tokens compared to LongCat-Flash-Chat's 128,000 tokens. Both models can generate responses up to 128,000 tokens.

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
Meituan
LongCat-Flash-Chat
Input128,000 tokens
Output128,000 tokens
Mon Oct 05 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Sonnet 5.5 supports multimodal inputs, whereas LongCat-Flash-Chat does not.

Claude Sonnet 5.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Sonnet 5.5

Text
Images
Audio
Video

LongCat-Flash-Chat

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Sonnet 5.5 is licensed under a proprietary license, while LongCat-Flash-Chat uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

Claude Sonnet 5.5

Proprietary

Closed source

LongCat-Flash-Chat

MIT

Open weights

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while LongCat-Flash-Chat was released on 2025-08-29.

Claude Sonnet 5.5 is 13 months newer than LongCat-Flash-Chat.

Claude Sonnet 5.5

Sep 28, 2026

6 days ago

1.1yr newer
LongCat-Flash-Chat

Aug 29, 2025

1.1 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while LongCat-Flash-Chat's cutoff date is not specified.

We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without LongCat-Flash-Chat's cutoff date.

Claude Sonnet 5.5

Jun 2026

LongCat-Flash-Chat

—

Provider Availability

Claude Sonnet 5.5 is available from Anthropic. LongCat-Flash-Chat is available from Meituan.

Claude Sonnet 5.5

anthropic logo
Anthropic
Input Price:Input: $2.00/1MOutput Price:Output: $10.00/1M

LongCat-Flash-Chat

meituan logo
Meituan
Input Price:Input: $0.30/1MOutput Price:Output: $1.20/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and LongCat-Flash-Chat side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
LongCat-Flash-Chat
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs LongCat-Flash-Chat.

Which is better, Claude Sonnet 5.5 or LongCat-Flash-Chat?

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 19.8. Claude Sonnet 5.5 is made by Anthropic and LongCat-Flash-Chat is made by Meituan. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 5.5 compare to LongCat-Flash-Chat in benchmarks?

Claude Sonnet 5.5 scores BenchCAD (with Python tool): 96.3%, ArXivMath (with tools): 95.2%, Global-MMLU: 92.1%, MILU: 91.6%, SWE-bench Multilingual: 90.3%. LongCat-Flash-Chat scores MATH-500: 96.4%, MMLU: 89.7%, IFEval: 89.6%, ZebraLogic: 89.3%, HumanEval: 88.4%.

Is Claude Sonnet 5.5 cheaper than LongCat-Flash-Chat?

LongCat-Flash-Chat is 6.7x cheaper for input tokens. Claude Sonnet 5.5 costs $2.00/M input and $10.00/M output via anthropic. LongCat-Flash-Chat costs $0.30/M input and $1.20/M output via meituan.

What are the context window sizes for Claude Sonnet 5.5 and LongCat-Flash-Chat?

Claude Sonnet 5.5 supports 1.0M tokens and LongCat-Flash-Chat supports 128K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 5.5 and LongCat-Flash-Chat?

Key differences include LLM Stats Score (58.0 vs 19.8), context window (1.0M vs 128K), input pricing ($2.00 vs $0.30/M), multimodal support (yes vs no), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and LongCat-Flash-Chat?

Claude Sonnet 5.5 is developed by Anthropic and LongCat-Flash-Chat is developed by Meituan.

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