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![slow_developer Avatar](https://lunarcrush.com/gi/w:24/cr:twitter::1461305890892570628.png) Haider. [@slow_developer](/creator/twitter/slow_developer) on x 46.4K followers
Created: 2025-07-14 13:35:00 UTC

what is the base model used for GPT-5?

gpt-4.5 is a smarter model and might support reasoning in gpt-5, but probably not as the base model

since gpt-5 needs to handle many tasks -- using gpt-4.5 for everything would take too much compute

openAI probably used a more optimized base, like o3, and layered the reasoning skills on top


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**Related Topics**
[o3](/topic/o3)
[open ai](/topic/open-ai)

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