Codex Usage Limits Explained: 5-Hour Window, Weekly Cap and Resets

Jonhisking · October 2, 2026

Codex, OpenAI's coding agent, is included in ChatGPT Plus, Pro and Business plans, and it is where most people now run into usage limits. Codex shares its allowance with ChatGPT Work, uses a 5-hour window and a weekly cap, and burns through them at very different speeds depending on the model. Here is how it works and how to get more out of it.

Which plans include Codex

Codex (and ChatGPT Work) usage is included with Plus ($20), Pro ($100, $200 or $500) and Business Standard and Premium seats. Usage is not unlimited: each plan gets an allowance, measured over two windows.

Two limits at once

The 5-hour window. A rolling allowance that starts with your first request. Use it up and you wait until the window resets. OpenAI restored the 5-hour window for Plus at the end of August 2026; at the time it said Pro 100 and Pro 200 would not have it for the coming months.

The weekly limit. A rolling seven-day cap on top. Hit it and you wait for the weekly reset, even if your 5-hour window is fresh.

Codex and ChatGPT Work draw from the same allowance.

How much you get, by model

OpenAI's help center gives estimated messages per 5-hour window. The model you pick changes the number enormously:

The low end of each range is long, multi-step tasks on a large codebase; the high end is short, simple requests. Higher Pro tiers scale up: Pro 200 is 10× Plus for new subscribers since September 29, 2026, and Pro 500 is 25×.

Ultrafast, available only on Pro 500, is a faster mode that uses your included usage and credits more quickly.

Why Codex uses the allowance so fast

Like every coding agent, Codex works in steps and sends its whole working context back to the model at each step: instructions, tool definitions, files it has read and earlier steps. A typical 25-step feature task sends around 1.6 million input tokens. On the API that task would cost about $0.72 on a Sol-class model and around $3.60 on GPT-6 Astra, which is why Astra's allowance is so much smaller. See What does an AI coding agent cost per task?

How to check your usage

OpenAI's help center points to Settings → Usage in ChatGPT, which shows your remaining allowance and reset times. Codex also warns you as you approach the limit.

When you hit the limit

1. Wait for the reset. The 5-hour window refills within hours.
2. Use a banked reset or buy an instant reset, available on eligible Plus and Pro accounts.
3. Use credits to keep going on plans that support them.
4. Upgrade to a higher Pro tier.
5. Use an API key with pay-as-you-go billing for overflow work.

How to stretch it

• Default to GPT-5.6 Sol or Terra. Use GPT-6 Astra only for the hard problems where you can see the difference: it uses several times the allowance.
• Use Luna for simple edits, renames and boilerplate.
• Keep tasks small and specific. Fewer steps means less context resent.
• Start fresh between unrelated tasks so old history is not carried along.
• Point Codex at the right files instead of letting it search the whole repo.
• Keep your instruction file short, and write it in English if you normally use another language: on GPT's tokenizer, Korean takes about 1.44× and Japanese 1.79× the tokens of English.

Many of the same habits apply to Claude Code: see How to save tokens in Claude Code.

Codex or Claude Code?

Both are included in $20, $100 and $200 plans with similar limit systems. The ChatGPT Pro vs Claude Max comparison covers the differences, and the coding agent calculator compares monthly API costs with every plan.

Limits change often. OpenAI's Codex and Work usage help page has the current numbers.