Grok 4 vs Grok 3: What's New and Which Should You Use?
xAI released Grok 4 in July 2025, just five months after Grok 3. This wasn't an incremental update - it was a massive leap in AI capabilities. This guide compares Grok 4 vs Grok 3 features, performance, and helps you decide which version suits your needs.
Grok 4 vs Grok 3: Quick Summary
- • Always-on reasoning mode
- • 256K context window
- • Multimodal (text, image, video)
- • Native real-time web search
- • PhD-level reasoning capabilities
- • Optional reasoning mode
- • 128K context window
- • Primarily text-based
- • Limited search capabilities
- • General-purpose assistant
Release Timeline
xAI surprised everyone by skipping Grok 3.5 entirely and jumping straight to Grok 4. Here's the timeline:
- February 2025: Grok 3 released with 10x more compute than Grok 2
- July 2025: Grok 4 and Grok 4 Heavy released
- November 2025: Grok 4.1 launched with improvements
- January 2026: Grok 3 made free for all users
Core Architecture Differences
Reasoning Mode
The Biggest Change
Grok 4 removed non-reasoning mode entirely. It's always in reasoning mode, designed for complex problem-solving rather than quick everyday questions.
- • Non-reasoning mode for quick answers
- • Reasoning mode for complex problems
- • Good all-rounder for any task
- • Always-on reasoning mode
- • Thinks for seconds to minutes
- • Designed for deep problem-solving
Context Window Comparison
| Feature | Grok 3 | Grok 4 |
|---|---|---|
| Context Window | 128,000 tokens | 256,000 tokens |
| Input Modalities | Text only | Text, Image, Video |
| Real-time Web Search | Limited | Native integration |
| Reasoning Mode | Optional (Think mode) | Always-on |
| Training Compute | 10x Grok 2 | 10x Grok 3 (RL) |
| Best For | General tasks, quick Q&A | Research, coding, complex analysis |
Benchmark Performance
Grok 4 shows significant improvements across all major AI benchmarks:
Grok 4 Benchmark Scores
- GPQA (Science): 87-88% (Leading all competitors)
- SWE-Bench (Coding): 72-75%
- Humanity's Last Exam: 45%
- AI Analysis Index: 73
Grok 3 Benchmark Scores
- GPQA (Science): ~75%
- SWE-Bench (Coding): ~55%
- Humanity's Last Exam: ~25%
- AI Analysis Index: 67
Grok 4 Heavy: Multi-Agent Version
Grok 4 Heavy is the multi-agent version that spins up several AI agents in parallel, each working independently on the same task. They compare results and converge on the best answer. Grok 4 Heavy is the first model to score 50% on Humanity's Last Exam.
Multimodal Capabilities
One of the biggest upgrades in Grok 4 is its multimodal processing:
- Text: Both models handle text input/output
- Images: Grok 4 can analyze and reason about images
- Video: Grok 4 supports video understanding
- Speech: Grok 4 can process audio inputs
Grok 3 is primarily a text-based model with limited image capabilities added later through updates.
Real-Time Search Integration
Knowledge Cutoff Solution
Both Grok 3 and Grok 4 have a knowledge cutoff of November 2024. However, Grok 4 has native web search that can actively search the internet and X (formerly Twitter) for real-time information. Grok 3's search capabilities are more limited.
Which Grok Should You Use?
Use Grok 3 When:
- • Quick everyday questions ("What's the weather?")
- • Simple conversational interactions
- • Cost-sensitive applications
- • Fast response time is priority
- • General-purpose assistant tasks
Use Grok 4 When:
- • Complex research and analysis
- • Advanced coding and debugging
- • Math, science, and technical problems
- • Processing large documents or codebases
- • Multi-step reasoning tasks
- • Image or video analysis needed
Pricing and Access
| Plan | Grok 3 Access | Grok 4 Access |
|---|---|---|
| Free (X Account) | Yes (with limits) | No |
| X Premium ($8/mo) | Yes | Limited |
| X Premium+ ($40/mo) | Yes | Yes |
| SuperGrok ($30/mo) | Yes | Yes |
| SuperGrok Heavy ($300/mo) | Yes | Yes + Grok 4 Heavy |
Future: Grok 5 Coming Soon
Looking Ahead
Elon Musk has announced Grok 5 is scheduled for early 2026, featuring a 6 trillion parameter model trained on xAI's Colossus 2 supercluster. Musk claims there's a "10% probability" of achieving the world's first AGI with this release.
Conclusion
Grok 4 represents a significant leap forward in AI capabilities, particularly for complex reasoning, multimodal processing, and real-time information retrieval. However, Grok 3 remains the better choice for everyday tasks where speed matters more than deep analysis.
For most users, starting with the free Grok 3 tier makes sense. Upgrade to Premium+ or SuperGrok when you need Grok 4's advanced capabilities for research, coding, or professional work.