Codex limits and Codex usage limits
The most frustrating way to lose work with Codex is a long agentic run that stops halfway because you've exhausted your usage. Here's how Codex usage limits work and how to stay ahead of them.
How Codex meters usage
Codex tracks usage against a rolling short window (around five hours) and a weekly window. Big, multi-step agent runs consume the short window fast; the weekly window quietly governs how much heavy work you can do across the whole week. You can sail through individual sessions and still run out mid-week.
How to check Codex usage
In Codex CLI, use /status to see current usage during a session. You can also check the Codex usage dashboard for plan limits. ReserveGauge puts that live remaining allowance in your menu bar and projects whether it lasts until reset.
Why long runs hit the wall
Agentic coding is bursty. A single "refactor this module and run the tests" can spend a large slice of your short window in minutes. Because the limit is rolling, the danger isn't a fixed daily quota, it's the pace over the last few hours. Without a forecast you only find out when the task halts.
The fix: forecast, don't guess
Instead of staring at a percentage, project your recent burn rate forward to the reset. If the projection crosses your limit before the window resets, you know now, and can ease off, switch to a lighter model, or finish the critical part first. If it lands comfortably under, you can push.
In practice
Say you kick off a big refactor on Monday afternoon and it eats a third of your weekly window in one sitting. The percentage still looks fine, but at that pace you would run dry by Wednesday. A forecast catches that on Monday, while you can still pace the rest of the week or move the heavy work to after the reset.
See it in your menu bar
ReserveGauge reads your live Codex (and Claude Code) limits directly on your Mac, forecasts your week from your real usage history, and warns you the moment you're on track to run out early. Your usage history stays on your Mac; provider names, allowance values and usage history are not sent to ReserveGauge.