How many parameters does GPT-5 have?
The sources reviewed for this article do not establish a confirmed numerical parameter count for GPT-5. AIMultiple reports that OpenAI does not disclose parameter counts for its GPT models, but that is third-party reporting—not an official GPT-5-specific statement. The OpenAI GPT-5 API model page reviewed for this article did not provide a parameter count in the information available. No number should be treated as an official specification on that basis. (AIMultiple; OpenAI GPT-5 API model page)
This is a limit of the evidence reviewed, not a claim that GPT-5 has no parameters. Some online sources report estimates, but estimates are not confirmed specifications; do not rely on a number without a traceable, credible source.
What should you compare for a production API?
An unconfirmed parameter count is not a sound stand-in for whether a model will work well or cost less for your application. Instead:
- Check current availability first. The OpenAI GPT-5 API model page describes GPT-5 as a previous model for coding, reasoning, and agentic tasks, and recommends GPT-6 Astra. That description does not, by itself, establish that GPT-5 is formally deprecated. Confirm the current model catalog and your account’s access before building around a model name. (OpenAI GPT-5 API model page)
- Test representative tasks. Compare quality, error rates, latency, and token usage on the prompts and workflows your application actually needs.
- Verify requirements in current documentation. Check supported inputs and outputs, context and output limits, tools, and pricing for the model you plan to use.
Bottom line
How many parameters does GPT-5 have? The sources reviewed for this article establish no confirmed number. Treat unsourced figures as estimates, not facts. For production use, verify which models are currently available, then test suitable options against your workload.
Sources reviewed for this answer: AIMultiple’s article on LLM parameter counts and OpenAI’s GPT-5 API model page. The cited OpenAI page describes GPT-5 as a previous model and recommends GPT-6 Astra.
Sources
LLM Parameters: Types, Scaling, Fine-Tuning Guide — AIMultiple