Grok-1.5 vs Grok-4 vs Grok-4 Heavy: all xAI models available today, technical features, practical differences, and subscription limits

Today, the xAI Grok ecosystem offers three distinct models, differentiated by subscription type.

On the X (formerly Twitter) AI platform, Grok is now available in three main versions: Grok-1.5, Grok-4, and Grok-4 Heavy. Each model matches a specific subscription plan, with different features and usage limits, offering both a solution for the general public and advanced options for power users and professional developers. Model selection happens directly inside the Grok chat on X or in the mobile apps, according to the plan active on the user’s profile.

Grok-4 is the flagship model aiming to outperform all competitors in advanced reasoning.

Grok-4 currently represents the top of xAI’s offering for SuperGrok subscribers, with capabilities claimed to surpass rivals like GPT-4 Turbo, Claude Opus, and Gemini 2.5 Pro in reasoning, coding, and academic test tasks. Its strength lies in a 256,000 token context window, allowing for the handling of extensive documents, complex threads, and multi-file datasets without losing references throughout the conversation.Grok-4’s architecture introduces the Deep Search mode, which can be activated for the most complex tasks: this function allows the AI to perform multiple reasoning and fact-checking passes, sacrificing a few seconds of latency to achieve deeper and more reliable answers.The direct connection with the X feed ensures up-to-date, real-time data: during inference, the chatbot can access posts, trends, Spaces, and recent mentions, directly citing the sources found in the timeline—a unique feature compared to all other top-tier chatbots.

Grok-4 Heavy pushes calculation power, depth, and available advanced reasoning minutes even further.

Grok-4 Heavy, available only to SuperGrok Heavy plan users, is designed for those who need consistent performance on long-duration tasks or large-scale software development. This model uses a boosted architecture (with GPU consumption double that of Grok-4) and offers 360 monthly minutes of Deep Search instead of the 120 included in the standard plan.The Heavy upgrade is specifically targeted at developers, data analysts, refactoring automations on entire codebases, and those running prolonged quantitative analyses or data mining.The plan’s price, set at $300 per month, is currently the highest in the consumer sector, justified by the combination of power, queue priority, and early access to new features.

Grok-1.5 remains the standard model for speed, live data access, and medium-long context.

Grok-1.5 is the included model for all X Premium subscribers. It stands out for a 128,000 token context window, extremely low response times, and continuous real-time access to X data.The 1.5 V variant, with vision support, adds the ability to interpret images within the conversation, expanding use cases for automations, assistance, brainstorming, and moderation.Grok-1.5 is the optimal solution for those seeking speed, high request volume (up to 200 messages per day), and the ability to validate information instantly with fact-checking on the X feed, making it unique for those working on news, trends, and social content.

The different subscription plans determine model access, Deep Search minutes, and daily usage limits.

X Premium (included with the $0/month subscription) allows use of Grok-1.5 up to 200 messages per day, with no Deep Search.SuperGrok ($30/month) unlocks Grok-4, with 1,000 messages per day and 120 monthly minutes of Deep Search for advanced tasks.SuperGrok Heavy ($300/month) gives priority access to Grok-4 Heavy, with 4,000 messages per day, 360 Deep Search minutes, and previews of new upcoming features.This structure allows users to choose the plan best suited to their real needs for depth, usage frequency, and the level of automation required.

Mixture-of-Experts architecture, multimodal support, and direct connection to X are the technical pillars of the Grok platform.

All Grok models are based on a Mixture-of-Experts architecture: only some “experts” are activated for each generated token, increasing efficiency and enabling the system to scale across very different tasks.Starting from Grok-1.5 V, it is possible to send images as input and receive multimodal analyses. Grok-4 also introduces on-device text-to-image generation, with progressive rollout to SuperGrok subscribers.What truly sets Grok apart from other chatbots is the direct connection to the X APIs: every model can consult, in real time, posts, mentions, and trends, and integrate this information into responses, providing chronological citations and verifiable sources within the conversation.

Declared limits, minimal moderation policy, and lack of transparency about datasets remain controversial aspects for xAI.

xAI has not yet made complete details public regarding training datasets, architectural parameters, or bias metrics for Grok-4 and Heavy, maintaining a “reduced” transparency philosophy compared to academic standards.Several recent cases have shown polarized or inappropriate responses, which the company justifies as part of a “free speech” policy with minimal moderation. This raises questions about Grok’s reliability in sensitive contexts, although xAI’s stated approach is to offer a model less constrained by the typical moderation rules of other sector players.

_______ SUMMARY TABLE

Model	Context Window	Multimodality	Deep Search Minutes	Subscription Required	Daily Message Limit	Best For	Unique Strengths
Grok-1.5	128,000 tokens	Text + Images (1.5 V)	Not available	X Premium (free/included)	200	Fast answers, news, trends, high volume	Real-time X data, low latency, vision support
Grok-4	256,000 tokens	Text + Images + Text→Image (beta)	120/month	SuperGrok ($30/month)	1,000	Deep reasoning, code, research, real-time facts	Deep Search, live feed X integration
Grok-4 Heavy	256,000 tokens	Text + Images + Text→Image (beta)	360/month	SuperGrok Heavy ($300/month)	4,000	Extended analysis, automation, dev workflows	Highest power, queue priority, early access

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