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OpenAI GPT-5.5 Pro VS xAI Grok 4.5

✍️ Analysis by:the whichllmmodel Editorial Team|📅 Updated: June 2026

📊Our Take

Standardized reasoning and coding benchmarks are currently pending verification for one or both of these models. We recommend testing GPT-5.5 Pro and Grok 4.5 directly in their respective provider playgrounds to see which fits your specific prompt styles best.
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Model Specs

GPT-5.5 Pro

Benchmarks & Scores

Coding (swe-bench-pro)
N/A

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)Winner (+3.2%)
96.2%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)
$67.50Input: $30.00 | Output: $180.00
Context WindowLarger
1.05M tokens
Model Specs

Grok 4.5

Benchmarks & Scores

Coding (swe-bench-pro)
64.7%

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)
93%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)22.5x cheaper
$3.00Input: $2.00 | Output: $6.00
Context Window
500k tokens

Frequently Asked Questions about GPT-5.5 Pro vs Grok 4.5 comparison

Grok 4.5 is cheaper than GPT-5.5 Pro. Grok 4.5 has a blended cost of $3.00/1M tokens, which is about 22.5x cheaper than GPT-5.5 Pro at $67.50/1M tokens.