Model Comparison

U2 vs Grok 4.5Which is better in 2026?

Comparing U2 and Grok 4.5 across benchmarks, pricing, and capabilities.

Verdict: U2 vs Grok 4.5 — which is better?

U2 (by Unisound) and Grok 4.5 (by xAI) 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 16.0x 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 16.0x cheaper per token

Choose Grok 4.5 if…

  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

U2 and Grok 4.5don'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 13.3x cheaper than Grok 4.5 ($2.00/1M tokens).

For output processing, U2 ($0.30/1M tokens) is 20.0x cheaper than Grok 4.5 ($6.00/1M tokens).

In conclusion, Grok 4.5 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
xAI
Grok 4.5
Input tokens$2.00
Output tokens$6.00
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Only Grok 4.5 specifies input context (500,000 tokens).

Unisound
U2
Input- tokens
Output- tokens
xAI
Grok 4.5
Input500,000 tokens
Output- tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok 4.5 supports multimodal inputs, whereas U2 does not.

Grok 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

U2

Text
Images
Audio
Video

Grok 4.5

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

U2

Proprietary

Closed source

Grok 4.5

Proprietary

Closed source

Release Timeline

When each model was launched

U2 was released on 2026-06-05, while Grok 4.5 was released on 2026-07-08.

Grok 4.5 is 1 month newer than U2.

U2

Jun 5, 2026

1 months ago

Grok 4.5

Jul 8, 2026

1 weeks ago

1mo newer

Knowledge Cutoff

When training data ends

U2 has a documented knowledge cutoff of 2026-01-31, while Grok 4.5'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 Grok 4.5's cutoff date.

U2

Jan 2026

Grok 4.5

—

Provider Availability

U2 is available from Unisound. Grok 4.5 is available from xAI.

U2

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

Grok 4.5

xai logo
xAI
Input Price:Input: $2.00/1MOutput Price:Output: $6.00/1M
* 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
xAI
Larger context window (500,000 tokens)
Supports multimodal inputs

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against U2 and Grok 4.5 side-by-side, then vote on the output you prefer.

U2
✓ Preferred
Grok 4.5
Open in Playground
AI Model Comparison Table
Feature
Unisound
U2
xAI
Grok 4.5

FAQ

Common questions about U2 vs Grok 4.5.

Which is better, U2 or Grok 4.5?

U2 (Unisound) and Grok 4.5 (xAI) 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 Grok 4.5 in benchmarks?

Grok 4.5 scores GPQA: 93.0%, Terminal-Bench 2.1: 83.3%, Artificial Analysis Coding Agent Index v1.1: 76.0%, SWE-Bench Pro: 64.7%, AA-Omniscience Index: 63.0%.

Is U2 cheaper than Grok 4.5?

U2 is 13.3x cheaper for input tokens. U2 costs $0.15/M input and $0.30/M output via unisound. Grok 4.5 costs $2.00/M input and $6.00/M output via xai.

What are the context window sizes for U2 and Grok 4.5?

U2 supports an unknown number of tokens and Grok 4.5 supports 500K 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 Grok 4.5?

Key differences include input pricing ($0.15 vs $2.00/M), multimodal support (no vs yes). See the full comparison above for benchmark-by-benchmark results.

Who makes U2 and Grok 4.5?

U2 is developed by Unisound and Grok 4.5 is developed by xAI.

Related comparisons