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OpenAI GPT-5.5 VS xAI Grok 4.5

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

👑Our Take

Grok 4.5 is the superior choice here. It holds a 3.3% average lead in benchmarks while actually being more cost-effective (saving 3.8x on API costs compared to GPT-5.5). Unless you have specific provider lock-in, go with Grok 4.5.
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Model Specs

GPT-5.5

Benchmarks & Scores

Coding (swe-bench-pro)
58.6%

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

Reasoning (gpqa-diamond)Winner (+0.6%)
93.6%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)
$11.25Input: $5.00 | Output: $30.00
Context WindowLarger
1.05M tokens
Model Specs

Grok 4.5

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+6.1%)
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)3.8x cheaper
$3.00Input: $2.00 | Output: $6.00
Context Window
500k tokens

Frequently Asked Questions about GPT-5.5 vs Grok 4.5 comparison

Grok 4.5 is cheaper than GPT-5.5. Grok 4.5 has a blended cost of $3.00/1M tokens, which is about 3.8x cheaper than GPT-5.5 at $11.25/1M tokens.

Grok 4.5 is better for coding tasks on this benchmark. It scores 64.7% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) compared to GPT-5.5 which scores 58.6%.