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Claude Mythos 5.1 vs LongCat-Flash-Chat

Claude Mythos 5.1 leads the LLM Stats Score 45.1 to 19.9. LongCat-Flash-Chat is 38.1x cheaper per token.

Anthropic · Meituan · Updated for 2026

Which is better?

Claude Mythos 5.1 leads the overall LLM Stats Score 45.1 to 19.9, ranking #31 overall.

On price, LongCat-Flash-Chat is roughly 38.1x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Claude Mythos 5.1 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 Mythos 5.1

  • overall performance matters — it scores 45.1 and ranks #31 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 38.1x cheaper per token
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Claude Mythos 5.1
Anthropic
LongCat-Flash-Chat
Meituan
Core performance indexes
LLM Stats Score
45.1
#31
19.9
#196
Reasoning
44.4
#34
19.8
#192
Coding
37.5
#17
12.4
#144
Agents
34.5
#21
9.2
#126
Cost, coverage & limits
Benchmark wins
—
—
Input price
$10.00 / M
$0.30 / M
Output price
$50.00 / M
$1.20 / M
Context window
1,000,000
128,000

Individual benchmarks

1 reported for Claude Mythos 5.1 · 16 for LongCat-Flash-Chat

No common benchmarks found

Claude Mythos 5.1 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 Mythos 5.1 ($10.00/1M tokens) is 33.3x more expensive than LongCat-Flash-Chat ($0.30/1M tokens).

For output processing, Claude Mythos 5.1 ($50.00/1M tokens) is 41.7x more expensive than LongCat-Flash-Chat ($1.20/1M tokens).

In conclusion, Claude Mythos 5.1 is more expensive than LongCat-Flash-Chat.*

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

Lowest available price from all providers
Wed Sep 09 2026 • llm-stats.com
Anthropic
Claude Mythos 5.1
Input tokens$10.00
Output tokens$50.00
Best providerAnthropic
Meituan
LongCat-Flash-Chat
Input tokens$0.30
Output tokens$1.20
Best providerMeituan
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Claude Mythos 5.1 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 Mythos 5.1
Input1,000,000 tokens
Output128,000 tokens
Meituan
LongCat-Flash-Chat
Input128,000 tokens
Output128,000 tokens
Wed Sep 09 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Mythos 5.1 supports multimodal inputs, whereas LongCat-Flash-Chat does not.

Claude Mythos 5.1 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Mythos 5.1

Text
Images
Audio
Video

LongCat-Flash-Chat

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Mythos 5.1 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 Mythos 5.1

Proprietary

Closed source

LongCat-Flash-Chat

MIT

Open weights

Release Timeline

When each model was launched

Claude Mythos 5.1 was released on 2026-09-01, while LongCat-Flash-Chat was released on 2025-08-29.

Claude Mythos 5.1 is 12 months newer than LongCat-Flash-Chat.

Claude Mythos 5.1

Sep 1, 2026

1 weeks ago

1.0yr newer
LongCat-Flash-Chat

Aug 29, 2025

1.0 years ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Claude Mythos 5.1 is available from Anthropic. LongCat-Flash-Chat is available from Meituan.

Claude Mythos 5.1

anthropic logo
Anthropic
Input Price:Input: $10.00/1MOutput Price:Output: $50.00/1M

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?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Mythos 5.1 and LongCat-Flash-Chat side-by-side, then vote on the output you prefer.

Claude Mythos 5.1
✓ Preferred
LongCat-Flash-Chat
Open in Playground

FAQ

Common questions about Claude Mythos 5.1 vs LongCat-Flash-Chat.

Which is better, Claude Mythos 5.1 or LongCat-Flash-Chat?

Claude Mythos 5.1 leads the LLM Stats Score 45.1 to 19.9. Claude Mythos 5.1 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 Mythos 5.1 compare to LongCat-Flash-Chat in benchmarks?

Claude Mythos 5.1 scores Terminal-Bench 4.0: 60.9%. LongCat-Flash-Chat scores MATH-500: 96.4%, MMLU: 89.7%, IFEval: 89.6%, ZebraLogic: 89.3%, HumanEval: 88.4%.

Is Claude Mythos 5.1 cheaper than LongCat-Flash-Chat?

LongCat-Flash-Chat is 33.3x cheaper for input tokens. Claude Mythos 5.1 costs $10.00/M input and $50.00/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 Mythos 5.1 and LongCat-Flash-Chat?

Claude Mythos 5.1 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 Mythos 5.1 and LongCat-Flash-Chat?

Key differences include LLM Stats Score (45.1 vs 19.9), context window (1.0M vs 128K), input pricing ($10.00 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 Mythos 5.1 and LongCat-Flash-Chat?

Claude Mythos 5.1 is developed by Anthropic and LongCat-Flash-Chat is developed by Meituan.

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