Grok 4.20 vs GPT-5.5Benchmark Comparison 2026

Objective comparison based on public benchmarks updated weekly: Intelligence Index, GPQA Diamond, Chatbot Arena ELO, pricing and speed.

xAI

Grok 4.20

Intelligence Index

37.0

Coding Index

58.5

4 criteria won

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OpenAI

GPT-5.5

ELO Arena

1482

Intelligence Index

54.8

Coding Index

82.5

4 criteria won

View full profile

Detailed Comparison

CritérioGrok 4.20GPT-5.5
Chatbot Arena ELO1482
Intelligence Index (AA)37.054.8
Coding Index (AA)58.582.5
GPQA Diamond91.0%94.0%
Input price ($/1M tok)$2.00$5.00
Output price ($/1M tok)$6.00$30.00
Context window2.0M tokens1.1M tokens
Speed (tokens/s)156 tok/s62 tok/s

✓ = winner in this criterion • Source: Artificial Analysis, LMArena, official APIs • Updated weekly

Technical Specifications

Grok 4.20

Company
xAI
Context window
2.0M tokens
Input ($/1M tok)
$2.00
Output ($/1M tok)
$6.00
Speed
156 tok/s
Release
Apr 2026
Multimodal
Yes
Open Source
No
Official website
Visit

GPT-5.5

Company
OpenAI
Context window
1.1M tokens
Input ($/1M tok)
$5.00
Output ($/1M tok)
$30.00
Speed
62 tok/s
Release
Apr 2026
Multimodal
Yes
Open Source
No
Official website
Visit

When to use Grok 4.20 vs GPT-5.5?

Choosing between Grok 4.20 and GPT-5.5 depends on your use case, budget and technical requirements. Below, a practical guide based on benchmark data and each model's specifications.

Use Grok 4.20 when:

xAI · Multimodal

  • Complex reasoning, math and advanced programming — reasoning models are optimized for problems requiring multiple logical steps
  • Processing images, PDFs and visual documents alongside text — useful for analyzing contracts, reports with charts and mixed content
  • Long document analysis — 2.0M tokens context window allows processing books, legal databases and extensive logs
  • AI agents with tool calling — workflow automation, external API integration and data pipelines
  • API integration in SaaS applications — direct API access with documented SLA
View full Grok 4.20 profile

Use GPT-5.5 when:

OpenAI · Multimodal

  • Processing images, PDFs and visual documents alongside text — useful for analyzing contracts, reports with charts and mixed content
  • Long document analysis — 1.1M tokens context window allows processing books, legal databases and extensive logs
  • API integration in SaaS applications — direct API access with documented SLA
View full GPT-5.5 profile

Frequently Asked Questions

Grok 4.20 or GPT-5.5: which is better?

Grok 4.20 and GPT-5.5 are evenly matched in this comparison. Choose based on the criterion most important for your project.

Where does this benchmark data come from?

Data is aggregated from Artificial Analysis (Intelligence Index, Coding Index) and Chatbot Arena/LMArena (ELO). Pricing and specs come from official APIs. Updated weekly.

What is the Intelligence Index?

The Intelligence Index is an aggregate score from Artificial Analysis that combines multiple academic benchmarks (MMLU, GPQA, LiveBench, etc.) into a single rating. The higher the score, the more capable the model is at reasoning tasks.

Is Grok 4.20 cheaper than GPT-5.5?

Yes. Grok 4.20 costs $2/1M input tokens, while GPT-5.5 costs $5/1M tokens — 150% more expensive. For high-volume projects, Grok 4.20 represents significant savings. Total cost also depends on output pricing and your application's usage pattern.

Grok 4.20 or GPT-5.5: which has a larger context window?

Grok 4.20 has the larger context window: 2.0M tokens vs 1.1M tokens. For long document analysis, extensive transcripts or full codebases, the larger context window is a decisive criterion.

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