So simply ask over ChatGPT.
Yes — your concern is reasonable. I checked the current OpenAI documentation and pricing pages, and there is an important distinction between “Codex is included with Plus” and how much Codex usage Plus actually includes.
What Plus currently gives you
The main ChatGPT pricing page describes Plus as having “Expanded Codex usage”, but it does not show a simple numeric Codex allowance directly beside the Plus purchase option. It links to a separate “Limits apply” page. citeturn1view0
Codex/Work usage is metered separately from ordinary ChatGPT chatting. OpenAI currently says that usage can be constrained by both a 5-hour window and a weekly window, and you need allowance remaining in the applicable limits to continue. citeturn1search6turn1search1
More importantly, it isn’t simply:
“You get X Codex prompts per week.”
Consumption varies according to the model, reasoning level, task complexity, context size, tools, and how long the task runs. A large repository or long agentic coding task can therefore consume dramatically more allowance than a small coding request. citeturn0search0
That is probably why it feels like the allowance disappears surprisingly quickly when you’re doing substantial development work.
Why wasn’t this obvious when buying Plus?
This is the part where the current presentation isn’t especially transparent.
The purchase page currently says:
Plus → “Expanded Codex usage”
and then:
“Limits apply”. citeturn1view0
It does not, in the main Plus feature list, say something straightforward such as:
Codex has a separate usage allowance.
Heavy coding tasks consume more allowance.
A weekly limit applies.
Work and Codex may share an allowance.
You have to follow the documentation to discover those details.
The Help Center is considerably clearer: it explicitly says that Codex, ChatGPT Work and some other agentic features can draw from the same allowance/credit pool, and that large codebases, extended sessions and long-running tasks consume substantially more. citeturn0search0turn0search8
So if your impression when purchasing Plus was “Plus includes Codex, therefore I’ll be able to use Codex reasonably freely throughout the month,” the pricing-page wording alone doesn’t give you a particularly good idea of how restrictive heavy Codex use may become.
One other thing worth knowing
Once the included allowance is exhausted, eligible Plus users can purchase additional credits rather than necessarily upgrading the whole subscription. OpenAI says the included allowance is consumed first and then eligible usage can draw from purchased credits. citeturn0search8
You can check the actual state of your account under Settings → Usage. Codex CLI also supports /status; OpenAI specifically recommends checking the usage dashboard for the exhausted allowance and reset time. citeturn0search0
urlOpenAI’s current ChatGPT pricing pageturn1view0
urlOpenAI’s Codex usage explanationturn0search0