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Claude Sonnet 5.5 vs Grok-1.5

Claude Sonnet 5.5 leads the LLM Stats Score 58.1 to -2.6.

Anthropic · xAI · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.1 to -2.6, ranking #3 overall.

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

Choose Claude Sonnet 5.5

  • overall performance matters — it scores 58.1 and ranks #3 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you want the most recent training data — it shipped Sep 2026

Choose Grok-1.5

  • you are already invested in the xAI ecosystem

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
Grok-1.5
xAI
Core performance indexes
LLM Stats Score
58.1
#3
-2.6
#347
Reasoning
56.6
#3
-2.2
#337
Coding
48.9
#2
-0.9
#253
Cost, coverage & limits
Benchmark wins
—
—
Input price
$2.00 / M
— / M
Output price
$10.00 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

3 shared
Index
Claude Sonnet 5.5
Grok-1.5
Math
36.9#34
4.9#279
Vision
40.1#3
-5.2#207
Multimodal
40.2#2
-2.6#166
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 9 for Grok-1.5

No common benchmarks found

Claude Sonnet 5.5 and Grok-1.5don'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

Context Window

Maximum input and output token capacity

Only Claude Sonnet 5.5 specifies input context (1,000,000 tokens). Only Claude Sonnet 5.5 specifies output context (128,000 tokens).

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
xAI
Grok-1.5
Input- tokens
Output- tokens
Tue Sep 29 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Claude Sonnet 5.5 supports multimodal inputs, whereas Grok-1.5 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

Grok-1.5

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.

Claude Sonnet 5.5

Proprietary

Closed source

Grok-1.5

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while Grok-1.5 was released on 2024-03-28.

Claude Sonnet 5.5 is 30 months newer than Grok-1.5.

Claude Sonnet 5.5

Sep 28, 2026

1 days ago

2.5yr newer
Grok-1.5

Mar 28, 2024

2.5 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Grok-1.5'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 Grok-1.5's cutoff date.

Claude Sonnet 5.5

Jun 2026

Grok-1.5

—

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and Grok-1.5 side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
Grok-1.5
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs Grok-1.5.

Which is better, Claude Sonnet 5.5 or Grok-1.5?

Claude Sonnet 5.5 leads the LLM Stats Score 58.1 to -2.6. Claude Sonnet 5.5 is made by Anthropic and Grok-1.5 is made by xAI. 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 Grok-1.5 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%. Grok-1.5 scores GSM8k: 90.0%, DocVQA: 85.6%, MMLU: 81.3%, HumanEval: 74.1%, MMMU: 53.6%.

What are the context window sizes for Claude Sonnet 5.5 and Grok-1.5?

Claude Sonnet 5.5 supports 1.0M tokens and Grok-1.5 supports an unknown number of 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 Grok-1.5?

Key differences include LLM Stats Score (58.1 vs -2.6), multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and Grok-1.5?

Claude Sonnet 5.5 is developed by Anthropic and Grok-1.5 is developed by xAI.

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