| Signal | Grok 4.20 | Delta | Grok 4 Fast |
|---|---|---|---|
Capabilities | 100 | -- | |
Pricing | 6 | +6 | |
Context window size | 100 | -- | |
Recency | 100 | +3 | |
Output Capacity | 20 | -55 | |
Benchmarks | 0 | -69 | |
| Overall Result | 2 wins | of 6 | 2 wins |
20
days higher
3
days
7
days higher
xAI
xAI
Grok 4 Fast saves you $455.00/month
That's $5460.00/year compared to Grok 4.20 at your current usage level of 100K calls/month.
| Metric | Grok 4.20 | Grok 4 Fast | Winner |
|---|---|---|---|
| Overall Score | 85 | 83 | Grok 4.20 |
| Rank | #22 | #55 | Grok 4.20 |
| Quality Rank | #22 | #55 | Grok 4.20 |
| Adoption Rank | #22 | #55 | Grok 4.20 |
| Parameters | -- | -- | -- |
| Context Window | 2000K | 2000K | -- |
| Pricing | $2.00/$6.00/M | $0.20/$0.50/M | -- |
| Signal Scores | |||
| Capabilities | 100 | 100 | Grok 4.20 |
| Pricing | 6 | 1 | Grok 4.20 |
| Context window size | 100 | 100 | Grok 4.20 |
| Recency | 100 | 97 | Grok 4.20 |
| Output Capacity | 20 | 75 | Grok 4 Fast |
| Benchmarks | -- | 70 | Grok 4 Fast |
Our composite score (0–100) combines six weighted signals: benchmark performance (25%), pricing efficiency (25%), context window size (15%), model recency (15%), output capacity (10%), and capability versatility (10%). Here's what the scores mean for these two models:
Scores 85/100 (rank #22), placing it in the top 93% of all 290 models tracked.
Scores 83/100 (rank #55), placing it in the top 81% of all 290 models tracked.
With only a 2-point gap, these models are in the same performance tier. The practical difference in output quality is minimal - your choice should depend on pricing, latency requirements, and specific feature needs.
Grok 4 Fast offers 91% better value per quality point. At 1M tokens/day, you'd spend $10.50/month with Grok 4 Fast vs $120.00/month with Grok 4.20 - a $109.50 monthly difference.
Both models have comparable response speeds. For most applications, the latency difference is negligible.
When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.
Code generation & review
Higher benchmark score (0/100) indicates stronger performance on coding tasks like generating functions, debugging, and refactoring
Customer support chatbot
Faster response time (speed score 0/100) is critical for user-facing chat. Grok 4 Fast also offers lower per-token costs for high-volume support
Long document analysis
Larger context window (2000K tokens) can process longer documents, contracts, and research papers in a single pass
Batch data extraction
Lower output pricing ($0.50/M) reduces costs when processing thousands of records daily
Creative writing & content
Higher overall composite score (85/100) correlates with better nuance, coherence, and style in long-form content
Image understanding & OCR
Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly
Grok 4.20 and Grok 4 Fast are extremely close in overall performance (only 2.0999999999999943 points apart). Your best choice depends entirely on which specific strengths matter most for your use case.
Best for Quality
Grok 4.20
Marginally better benchmark scores; both are excellent
Best for Cost
Grok 4 Fast
91% lower pricing; better value at scale
Best for Reliability
Grok 4.20
Higher uptime and faster response speeds
Best for Prototyping
Grok 4.20
Stronger community support and better developer experience
Best for Production
Grok 4.20
Wider enterprise adoption and proven at scale
by xAI
| Capability | Grok 4.20 | Grok 4 Fast |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoning | ||
| Web Search | ||
| Image Output |
xAI
xAI
Grok 4 Fast saves you $9.84/month
That's 91% cheaper than Grok 4.20 at 1,000 tokens/request and 100 requests/day.
Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.
| Parameter | Grok 4.20 | Grok 4 Fast |
|---|---|---|
| Context Window | 2M | 2M |
| Max Output Tokens | -- | 30,000 |
| Open Source | No | No |
| Created | Mar 31, 2026 | Sep 19, 2025 |
Grok 4.20 scores 85/100 (rank #22) compared to Grok 4 Fast's 83/100 (rank #55), giving it a 2-point advantage. Grok 4.20 is the stronger overall choice, though Grok 4 Fast may excel in specific areas like cost efficiency.
Grok 4.20 is ranked #22 and Grok 4 Fast is ranked #55 out of 290+ AI models. Rankings use a composite score combining benchmark performance (25%), pricing (25%), context window (15%), recency (15%), output capacity (10%), and versatility (10%). Scores update hourly.
Grok 4 Fast is cheaper at $0.50/M output tokens vs Grok 4.20's $6.00/M output tokens - 12.0x more expensive. Input token pricing: Grok 4.20 at $2.00/M vs Grok 4 Fast at $0.20/M.
Grok 4.20 has a larger context window of 2,000,000 tokens compared to Grok 4 Fast's 2,000,000 tokens. A larger context window means the model can process longer documents and conversations.