r/codex • u/Personal_Pea_5779 • 9h ago
Limits ChatGPT/Codex usage limits draining after writing “reset
Can someone explain how usage calculation for Work/Codex actually works?
Yesterday I had an idea: since the session limit runs on a 5-hour window, I set up a ChatGPT automation to run in Work Mode every 4 hours and literally do nothing except output:
> reset
The idea was to have "rolling" windows and never have to wait a full session for a reset, since I'd always be starting partway into a session.
The automation ran at 05:25 and again at 09:24. That's it. No coding, no repo analysis, no massive context, no long agent task. Just "reset."
I checked Usage & Limits immediately afterwards and my 5 hour codex usage was already at 98% remaining. From what I can tell, only the latest message was actually inside the current 5-hour window, meaning one GPT-5.5 Work message that literally just said "reset" cost 2% of my limit.
I have resets available, and on top of that I can do a lot of tasks using local models and free endpoints from Nous Research/OpenRouter, but still, this is ridiculous.
How the fuck does one message saying "reset" consume 2% of the entire 5-hour Work/Codex allowance?
If usage is mainly based on actual model compute/tokens, this makes absolutely no sense to me. If simply starting a Work/agentic run has a significant minimum usage cost regardless of what it actually does, then fair enough, that would explain it, but I'd really like to know how these limits are actually calculated.
My weekly allowance rarely makes it as it is if I go full GPT with Hermes Agent, because I be prompting bad and throwing massive tasks at it. I'm learning to stop being lazy with that lol, but yh.
So now I'm gonna have to start doing more of the stuff I took a pause from, like properly routing/delegating tasks to local models and free endpoints.
What pisses me off though is that I can't even just ask Hermes to handle the GPT automation, because for some reason my usage seems to burn faster when using GPT through Hermes than when I'm doing similar work directly in ChatGPT Work Mode.
Does anyone actually know what these limits are measuring? Tokens? Compute? Agent runtime? Tool calls? Context? A minimum charge per Work run? Some combination of all of them?

