Grok Models Explained: Grok 4.3, 4.20, 4.1 Fast & Grok 4 Heavy (2026)

xAI's Grok is a family of models, not one: Grok 4.3 is the flagship with a 1M token context window, while Grok 4.20 and Grok 4.1 Fast offer a larger 2M token window, and Grok 4 Heavy runs multi-agent for the hardest tasks. The newest model is not automatically the largest-context one, so the right pick depends on your task and budget. This guide breaks down the 2026 Grok lineup, context windows, and pricing, and it is accurate as of July 2026 per xAI's docs. AI Toolbox adds search, folders, and export on top of any Grok model.

By Adi Leviim, Co-Founder at Infi Developments, 7+ years building AI productivity tools.

What Grok Models Are Available in 2026?

As of July 2026, xAI keeps several Grok versions live at once with different context windows and price points. The headline flagship is Grok 4.3, but the largest-context and cheapest options sit on different version numbers, which is why picking a model is not simply "use the newest."

• Grok 4.3 is the flagship, released April 17, 2026 with a December 2025 knowledge cutoff. It has a 1M token context window, native video input, document generation for PDFs, spreadsheets, and slides, improved tool-calling, and xAI's claim of a low hallucination rate.
• Grok 4.20 offers a larger 2M token context window and agentic variants with reasoning, non-reasoning, and multi-agent modes for long tasks.
• Grok 4.1 Fast is the cheap, high-throughput option, also with a 2M token context window, tuned for low-latency responses.
• Grok 4 Heavy is the multi-agent heavy tier for the most demanding problems, offered through xAI's top SuperGrok Heavy plan.
• Grok 5 has been reported in training on the Colossus 2 supercomputer, with an expected arrival later in 2026.

For the authoritative, current list and specs, xAI publishes its models at docs.x.ai. Whichever model you use, AI Toolbox for Grok works on top of it.

Grok Model Comparison (2026)

Prices reflect xAI's published rates as of July 2026 and can change; check docs.x.ai for the latest. xAI does not publish a separate maximum-output cap, so Grok output is bounded by the model's context window.

Which Grok Model Should You Use?

Match the model to the job rather than always reaching for the flagship.

• Everyday reasoning, coding help, and multimodal work: Grok 4.3, the flagship, is the default.
• Very long documents or agent runs: Grok 4.20 or Grok 4.1 Fast, because their 2M window is double the flagship's.
• High volume on a budget: Grok 4.1 Fast is the cheap, fast option.
• The hardest, multi-step problems: Grok 4 Heavy on the SuperGrok Heavy plan.

On the consumer side, SuperGrok (around $30/month) provides access to Grok 4 and Grok 4.1 with DeepSearch and Big Brain mode, while SuperGrok Heavy (around $300/month) adds Grok 4 Heavy. Pricing and access change often, so confirm on xAI's site.

Context Windows: Why Bigger Is Not Always the Newest

A model's context window sets how much conversation and document text it can consider at once, and in Grok's lineup the flagship is not the largest. Grok 4.3 holds 1M tokens, while the older Grok 4.20 and Grok 4.1 Fast hold 2M. If you routinely paste large codebases, long PDFs, or entire research folders into a single chat, a 2M-window model can matter more than the flagship's newer reasoning.

One important caveat: these are the models' maximum windows, available through the xAI API. The everyday Grok web interface on x.com/i/grok and grok.com enforces a smaller working window, around 128K tokens on the free tier, with larger windows on paid SuperGrok tiers. In other words, having a 2M-capable model does not mean the free web UI gives you 2M, so plan around the window your plan and surface actually provide.

No matter the window size, long chats still fill up, and Grok gives no native indication of how full a conversation is. The AI Toolbox context window meter shows tokens used and messages remaining so you can start a fresh chat before older context is dropped.

Using AI Toolbox with Any Grok Model

AI Toolbox (formerly ChatGPT Toolbox) operates at the browser level on x.com/i/grok and grok.com, independent of which Grok model you select. It adds the productivity layer Grok lacks: full-text search across every message, folders and Smart Tags, Context Mentions (@@), a prompt library, and bulk export as TXT, Markdown, JSON, or PDF. Whether you run Grok 4.3 for reasoning or Grok 4.1 Fast for volume, your history stays searchable and organized. AI Toolbox is also available for ChatGPT, Gemini, and Claude.

Whichever Grok model you use, don't lose your chats. AI Toolbox adds full-text search, folders, and export to Grok on X and grok.com. Trusted by 35,000+ users with a 4.5/5 Chrome Web Store rating. Compare Grok plans →

Frequently Asked Questions

What is the latest Grok model in 2026?

Grok 4.3, released April 17, 2026, is xAI's flagship model. It has a 1M token context window, native video input, and document generation. Grok 5 has been reported in training with an expected arrival later in 2026.

Which Grok model has the biggest context window?

Grok 4.20 and Grok 4.1 Fast both have a 2M token context window, which is larger than the flagship Grok 4.3's 1M. Those are API maximums; the Grok web UI works with a smaller window, around 128K tokens on the free tier. If you feed in very long documents, one of the 2M-window models via the API may suit you better than the newest one.

How much does the Grok API cost?

As of July 2026, Grok 4.3 and Grok 4.20 are about $1.25 per 1M input tokens and $2.50 per 1M output tokens, Grok 4.1 Fast is roughly $0.20 / $0.50, and Grok Build 0.1 is $1.00 / $2.00. Check docs.x.ai for current rates.

What is Grok 4 Heavy?

Grok 4 Heavy is xAI's multi-agent heavy tier for the hardest problems, offered through the SuperGrok Heavy plan (around $300/month). It runs multiple agents in parallel to tackle complex, multi-step tasks.

Does AI Toolbox work with every Grok model?

Yes. AI Toolbox works at the browser level on x.com/i/grok and grok.com and is independent of your Grok model. It adds full-text search, folders, Smart Tags, a prompt library, a context meter, and export on top of any model.

Want to get more out of whichever Grok model you use? Install AI Toolbox free, open Grok, and search, organize, and export your chats. See AI Toolbox pricing and more Grok guides.

Last updated: July 9, 2026