Model Comparison

Grok-1.5 vs Grok 4.5Which is better in 2026?

Grok 4.5 significantly outperforms across most benchmarks.

Verdict: Grok-1.5 vs Grok 4.5 — which is better?

Grok-1.5 (by xAI) 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.

Grok-1.5 outperforms in 0 benchmarks, while Grok 4.5 is better at 1 benchmark (GPQA). Grok 4.5 significantly outperforms across most benchmarks.

Choose Grok-1.5 if…

  • you are already invested in the xAI ecosystem

Choose Grok 4.5 if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

Grok-1.5 outperforms in 0 benchmarks, while Grok 4.5 is better at 1 benchmark (GPQA).

Grok 4.5 significantly outperforms across most benchmarks.

Sat Jul 18 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

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

xAI
Grok-1.5
Input- tokens
Output- tokens
xAI
Grok 4.5
Input500,000 tokens
Output- tokens
Sat Jul 18 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok 4.5 supports multimodal inputs, whereas Grok-1.5 does not.

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

Grok-1.5

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.

Grok-1.5

Proprietary

Closed source

Grok 4.5

Proprietary

Closed source

Release Timeline

When each model was launched

Grok-1.5 was released on 2024-03-28, while Grok 4.5 was released on 2026-07-16.

Grok 4.5 is 28 months newer than Grok-1.5.

Grok-1.5

Mar 28, 2024

2.3 years ago

Grok 4.5

Jul 16, 2026

2 days ago

2.3yr newer

Knowledge Cutoff

When training data ends

Grok 4.5 has a documented knowledge cutoff of 2026-02-01, while Grok-1.5's cutoff date is not specified.

We can confirm Grok 4.5's training data extends to 2026-02-01, but cannot make a direct comparison without Grok-1.5's cutoff date.

Grok-1.5

—

Grok 4.5

Feb 2026

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

xAI

No standout differentiators in the data we have for this pair.

xAI
Larger context window (500,000 tokens)
Supports multimodal inputs
Higher GPQA score (93.0% vs 35.9%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Grok-1.5 and Grok 4.5 side-by-side, then vote on the output you prefer.

Grok-1.5
✓ Preferred
Grok 4.5
Open in Playground
AI Model Comparison Table
Feature
xAI
Grok-1.5
xAI
Grok 4.5

FAQ

Common questions about Grok-1.5 vs Grok 4.5.

Which is better, Grok-1.5 or Grok 4.5?

Grok 4.5 significantly outperforms across most benchmarks. Grok-1.5 is made by xAI and Grok 4.5 is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok-1.5 compare to Grok 4.5 in benchmarks?

Grok-1.5 scores GSM8k: 90.0%, DocVQA: 85.6%, MMLU: 81.3%, HumanEval: 74.1%, MMMU: 53.6%. 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%.

What are the context window sizes for Grok-1.5 and Grok 4.5?

Grok-1.5 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 Grok-1.5 and Grok 4.5?

Key differences include multimodal support (no vs yes). See the full comparison above for benchmark-by-benchmark results.

Related comparisons