Direct answer
The OpenAI GPT-5 material retrieved for this answer does not establish a confirmed parameter count. The launch post and system-card material describe GPT-5 as a system with multiple components, but the passages retrieved do not give a parameter total. This is a limited finding about the material reviewed here—not proof that no disclosure exists elsewhere.
What about estimates?
A third-party article reports conflicting online estimates, but the figures it describes are not confirmed GPT-5 specifications. Treat them as unverified, not as the answer to how many parameters GPT-5 has.
Keep variants distinct, too: APX lists 100B (estimated) for GPT-5 Mini, not GPT-5. That third-party estimate does not establish the parameter count of GPT-5 or the GPT-5 family.
Production API takeaway
Don’t use a rumored parameter count as a production selection fact. Check the current official API documentation for the models actually available to you, compare documented capabilities relevant to your task, and test candidates on your own workload. OpenAI’s GPT-5 system-card material describes distinct system components and API model access; verify current availability and details in the applicable API documentation.