Model Comparison

U2 vs GLM-5.1Which is better in 2026?

Comparing U2 and GLM-5.1 across benchmarks, pricing, and capabilities.

Verdict: U2 vs GLM-5.1 — which is better?

U2 (by Unisound) and GLM-5.1 (by Zhipu AI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

On price, U2 is roughly 11.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Choose U2 if…

  • cost matters — it's about 11.5x cheaper per token
  • you want the most recent training data — it shipped Jun 2026

Choose GLM-5.1 if…

  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

U2 and GLM-5.1don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

U2 costs less

For input processing, U2 ($0.15/1M tokens) is 9.3x cheaper than GLM-5.1 ($1.40/1M tokens).

For output processing, U2 ($0.30/1M tokens) is 14.7x cheaper than GLM-5.1 ($4.40/1M tokens).

In conclusion, GLM-5.1 is more expensive than U2.*

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

Lowest available price from all providers
Fri Jul 17 2026 • llm-stats.com
Unisound
U2
Input tokens$0.15
Output tokens$0.30
Best providerUnisound
Zhipu AI
GLM-5.1
Input tokens$1.40
Output tokens$4.40
Best providerFriendliAI
Notice missing or incorrect data?Start an Issue→

Model Size

Parameter count comparison

488.0B diff

GLM-5.1 has 488.0B more parameters than U2, making it 183.5% larger.

Unisound
U2
266.0Bparameters
Zhipu AI
GLM-5.1
754.0Bparameters
266.0B
U2
754.0B
GLM-5.1

Context Window

Maximum input and output token capacity

Only GLM-5.1 specifies input context (200,000 tokens). Only GLM-5.1 specifies output context (128,000 tokens).

Unisound
U2
Input- tokens
Output- tokens
Zhipu AI
GLM-5.1
Input200,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

License

Usage and distribution terms

U2 is licensed under a proprietary license, while GLM-5.1 uses MIT.

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

U2

Proprietary

Closed source

GLM-5.1

MIT

Open weights

Release Timeline

When each model was launched

U2 was released on 2026-06-05, while GLM-5.1 was released on 2026-04-07.

U2 is 2 months newer than GLM-5.1.

U2

Jun 5, 2026

1 months ago

1mo newer
GLM-5.1

Apr 7, 2026

3 months ago

Knowledge Cutoff

When training data ends

U2 has a documented knowledge cutoff of 2026-01-31, while GLM-5.1's cutoff date is not specified.

We can confirm U2's training data extends to 2026-01-31, but cannot make a direct comparison without GLM-5.1's cutoff date.

U2

Jan 2026

GLM-5.1

—

Provider Availability

U2 is available from Unisound. GLM-5.1 is available from FriendliAI, ZAI.

U2

unisound logo
Unisound
Input Price:Input: $0.15/1MOutput Price:Output: $0.30/1M

GLM-5.1

friendli logo
FriendliAI
Input Price:Input: $1.40/1MOutput Price:Output: $4.40/1M
z logo
Unknown Organization
Input Price:Input: $1.40/1MOutput Price:Output: $4.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Unisound
Less expensive input tokens
Less expensive output tokens
Zhipu AI
Larger context window (200,000 tokens)
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against U2 and GLM-5.1 side-by-side, then vote on the output you prefer.

U2
✓ Preferred
GLM-5.1
Open in Playground
AI Model Comparison Table
Feature
Unisound
U2
Zhipu AI
GLM-5.1

FAQ

Common questions about U2 vs GLM-5.1.

Which is better, U2 or GLM-5.1?

U2 (Unisound) and GLM-5.1 (Zhipu AI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does U2 compare to GLM-5.1 in benchmarks?

GLM-5.1 scores Vending-Bench 2: 100.0%, AIME 2026: 95.3%, HMMT 2025: 94.0%, GPQA: 86.2%, IMO-AnswerBench: 83.8%.

Is U2 cheaper than GLM-5.1?

U2 is 9.3x cheaper for input tokens. U2 costs $0.15/M input and $0.30/M output via unisound. GLM-5.1 costs $1.40/M input and $4.40/M output via friendli.

What are the context window sizes for U2 and GLM-5.1?

U2 supports an unknown number of tokens and GLM-5.1 supports 200K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between U2 and GLM-5.1?

Key differences include input pricing ($0.15 vs $1.40/M), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes U2 and GLM-5.1?

U2 is developed by Unisound and GLM-5.1 is developed by Zhipu AI.

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