Grok-4 Heavy

by xAI

Grok-4 Heavy is a model from xAI, released on July 9, 2025. It ranks #45 of 220 models by Intelligence Score with a score of 40.6.

Grok 4 Heavy is the multi-agent version of Grok 4, released alongside the standard model in summer 2025. This system spawns multiple Grok 4 agents in parallel that work independently on problems and then collaborate by comparing their solutions, similar to a study group. The agents share insights and tricks they discover, with the system intelligently combining their work rather than simply using majority voting. Grok 4 Heavy uses approximately 10x more test-time compute than regular Grok 4, enabling it to solve significantly more complex problems. On the Humanities Last Exam, it achieves over 50% accuracy on text-only problems, and it scored a perfect result on the AIME 2025 mathematics competition. The system represents a major advancement in multi-agent AI collaboration and reasoning capabilities.

Key specs

ProviderxAI
Release date2025-07-09
Licenseproprietary
Intelligence Score40.6
Coding index17.6

Quick answers

Is Grok-4 Heavy open source?

No. Grok-4 Heavy is a proprietary model from xAI (proprietary license).

When was Grok-4 Heavy released?

xAI released Grok-4 Heavy on July 9, 2025.

How does Grok-4 Heavy compare to Claude Opus 5.5 (Reasoning)?

Grok-4 Heavy scores 40.6 on the Intelligence Score versus 60.5 for Claude Opus 5.5 (Reasoning), the current #1.

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