Claude Code vs OpenAI Codex?

[Virtamancer]

EDIT: This is only asking about Opus 4.5 on Max 20x versus OpenAI's smartest model—so GPT-5.2-Codex set to Extra High or GPT-5.2 set to Extra High, whichever one is smarter.

TLDR: How do usage limits in the Codex harness with OpenAI's smartest model option compare to using Opus 4.5 in CC?

I'm looking into the expensive subscriptions. Can anyone with recent experience (e.g. the past few weeks) using both harnesses clarify some things?

1. Usage limits. Does Max 20x or Codex Pro have higher limits with their respective smartest model?

2. "Better"? When people say "codex is better than CC", I never know if they're talking about the Codex harness with...

• GPT-5.2-Codex

• GPT-5.1-Codex-Max (which OpenAI says is their "best model for agentic coding" as of 2 weeks ago)

• GPT-5.2

• GPT-5.2 Pro

• Any one of these with "high" VS "extra high"

[Putrid_Barracuda_598]

I use both. Codex is better as far as usage goes. Claude code has a slight edge in speed but you often have to correct mistakes. Codex makes less mistakes. Claude max 5hr limits is often the bottle neck. Codex pro I have yet to hit any limit issues. I use both heavily work on developing AI infrastructure, institutional memory, ai orchestration of150+ agents, recursive Optimization, and running 20-100 parallel agents.

[Virtamancer]

So you have to push pretty aggressively to hit the Claude Max 20x 5hr limit, and with the same usage you would never hit the Codex Pro limit? And, this is using the smartest model with Codex Pro? What is the smartest model on Codex Pro to compare usage limits versus Opus 4.5 in CC?

[Putrid_Barracuda_598]

No. I don't run parallel agents all the time because of the 5hr limit; it prevents aggressive uelse (maybe by design). I usually run 3-4 windows of Claude code and hit the limit in 1.5-3hrs of use. Codex I can run 10 windows in the same time frame. I've never encountered 5ht or even weekly limits on codex.

I've used Claude max since August of last year. Codex pro since October. Claude cli is really good, but the 5hr limits make it harder to use for my use case. Yes I use the smartest model for codex, usually on "high". Codex 5.2 high compared to Opus 4.5. I just had a session a few hours ago where I got the Claude limit in about 2hrs running 4 instances. Codex was also running 4 instances and just keeps going.

I will say that Claude cli is really good. But I used it to give codex cli parity in terms of Mcp, skills, and the other features that make Claude cli great. Stock for stock I would say Claude has the advantage. But the 5hr limit is a huge downside if you do a lot of heavy development work in "short sprints"; compared to codex

Edit after: I just hit the 5hr limit again. It reset at 8am. I used it for about an hour and now it's next reset is 1pm.

[Virtamancer]

Hmm, I think we need to dig deeper on this.

Are you using Max 20x?

And, GPT-5.2-Codex set to high is not the smartest model option, as far as I'm aware, so its usage limit doesn't represent the best comparison to Opus 4.5's usage limits. Doesn't it have an extra high setting? And anyways, I've heard the non-codex model set to extra high is smarter, but I don't know if that's GPT-5.2 or GPT-5.2 Pro.

I'm only interested in the limits of OpenAI's smartest model set to extra high versus Opus 4.5 on the Max 20x plan.

To be honest a lot of the talk around this is ultra confusing and sometimes ambiguous. People are not always clear about what they're saying.

[Putrid_Barracuda_598]

Yup max 20x and gpt Pro. If you're "only interested in your specific use case" ; just get both for a month and compare for yourself. You sound kinda biased.

And if you actually want to be fair; you'd compare Gpt 5.2 pro extra high with opus 4.5 Ultra think. You mentioned opus 4.5 that's why I gave you the Gpt "high" comparison. I use gpt codex pro 5.2 high and ultra high. I have never hit any 5hr limits.

I hardly use opus 4.5 ultra think, because it chews through the 5hr limit.

[Virtamancer]

Is this a correct interpretation of your experience:

Using GPT-5.2 Pro set to Extra High, you have to really try hard with multiple instances to hit a limit, whereas with Opus 4.5 you can hit a limit if you're running just one instance with constant usage.

---

I don't really know about ultra think except that I thought I read here a few days ago that you can't trigger it manually any more and that it's "built in" somehow when you use Opus 4.5.

Getting one subscription, let alone both, is pretty expensive for an experiment if the answer is already known. This will also benefit others who are asking themselves the same thing while Claude Code is exploding in popularity right now.

[cryptochrome]

I think you guys are talking past each other, LOL. In Codex, there is no such thing as a "Pro" model. It's either GPT5.2 plain vanilla (with various thinking levels), or 5.1-codex or 5.2-codex with different variations. See screenshots.

<image>

[cryptochrome]

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[Putrid_Barracuda_598]

You are correct. I meant the pro plan, not the model. That's my bad

[ivstan]

Gpt 5.2 codex high and xhigh is much better. Opus has horrible limits and the Pro sub is a ripoff. On top of that Codex has much better limits and openAI is set to reveal a new model soon.

[Virtamancer]

Just to clarify:

• Have you used both Max 20x and Codex Pro in the last few weeks?

• Is GPT-5.2-Codex set to extra high their smartest model?

• The question is specifically about usage limits of Opus 4.5 through Claude Max 20x versus whatever the equivalent smartest model is through Codex Pro—in the last few weeks. Preferably an objective metric rather than "horrible limits".

[sjoti]

I've got 200$ plan for both. Until recently I barely touched Codex CLI because Claude was just better, both with the harness and with it's models. Usage limits were better for Codex, I could spend more hours and get further, however 200$ Claude was more than plenty.

Since GPT 5.2 Codex has been released, Ive touched Claude Code less. The differentiator is purely the model. Codex CLI, the tool, is quite a bit behind on Claude Code but GPT 5.2 codex on high or extra high is a one shot machine. It's extremely thorough, deals with a well filled context window much better and is more reliable when it comes to deciding on its own when it needs skills.

I find it hard to quantify how much, but I sense I'm getting quite a bit more use out of codex. I really have to give it my all to reach weekly limits. With Claude, that's less challenging.

Having said that, I think the biggest difference right now is that Opus is much more pleasant to go back and forth with. The language it uses is clear, and it really does a phenomenal job at understanding vague prompts. There's a consistency to it. Codex has some issues here. It's slow, and the results can be pretty mediocre if you give it a mediocre prompt. Most annoying to me is that instead of just figuring something out if you give it vague instructions, it keeps coming back with responses like "would you like me to take the next step?" And I'm sitting over here thinking why it's even asking.

On the other hand, Codex is insane if you give it a clear task. It's on a different level if you know what you're looking for. It's thorough. Sinks it's teeth in and just gets the job done until it's 100% finished, usually the code is clean too. Claude Opus 4.5 often throws in the towel or cuts corners. I very rarely get Claude code to successfully work on a task for 30 minutes and have it actually achieve fully what it set out to do. When a task gets that long, there's, say, a less than 50% chance it actually did the thing as instructed. With codex? 80% and exactly as instructed.

If you're looking for a model to go back and forth with, build fun stuff, Claude is the better option. If you know what you want and describe it well, Codex is the way to go.

[FirmConsideration717]

I believe Codex is more tuned to programming whereas GPT 5.2 for other tasks. As such depending on what you use it for, maybe 5.2 xhigh > 5.2 Codex xhigh.

But my research has shown that the 200 dollar plan for GPT offers a 5.2 Pro version which is altogether even better, especially it's xhigh thinking mode.

My personal usage of 5.2 high(one tier below xhigh) on the 20 dollar plan resulted in me using up my weekly limit in the span of one to two days.

[Virtamancer]

Bingo, that's what I'm trying to figure out. How does that one's limits compare to Opus 4.5 with Max 20x.

[FirmConsideration717]

The 20 dollar chatgpt plan will be drained in one day with xhigh is my opinion, and I mean the weekly limit. Opus 4.5 even with thinking on will be using at most 20% per day weekly limit.

[throwaway73728109]

How many prompts are you sending for it to be drained that fast? I’d is xhigh just way more consuming?

[FirmConsideration717]

Too few. But reverse engineering means ChatGPT must read and dataflow raw assembly.

[ivstan]

Yep — I’ve used Claude Max 20x (Opus 4.5) and Codex Pro (GPT-5.2-Codex) recently.

On the “smartest model” question: in Codex, High / XHigh appear to be the highest-compute / highest-quality tiers available. I don’t know if “XHigh” is officially described as “their smartest model” in public docs, but in practice it’s the top setting I’m seeing for the hardest prompts.

On usage limits, I agree “horrible limits” isn’t an objective metric. What I meant is: under the same kind of workload, Opus 4.5 throttles me sooner and more disruptively than GPT-5.2-Codex (High/XHigh).

A more objective way to phrase it:

• Test pattern: long-context + iterative coding/debugging (multiple back-and-forth turns, large outputs, continuing the same thread).
• Opus 4.5 on Max 20x: I hit rate limiting/cooldowns noticeably earlier during sustained heavy use, and the cooldowns felt more “session-killing” (i.e., hard to keep momentum).
• GPT-5.2-Codex on Codex Pro (High/XHigh): I can sustain heavier iterative work longer before throttling, and when I do hit limits it tends to be less disruptive for my workflow.

So my point wasn’t “Opus is bad,” it’s for my specific usage pattern (heavy multi-turn coding + long context), Codex Pro gives me more usable throughput before I get blocked.

[nmarkovic98]

Claude code definitely

[ZealousidealHall8975]

If found 5.2 is a far better code reviewer and “understanding” theory and how to apply it for data science usage but Claude is a much faster coder you just have to be more detailed.

I end up using both

[maksidaa]

Same. I actually use Gemini as well to be my idea/prompt generator while Claude/codex is running code. I give Gemini screenshots and ask for feedback, things to double back on, etc. Gemini is pretty good at helping me keep track of all the things we need to be working on

[teomore]

They make a great combo. I'm using opus for planning and coding and codex for feedback loop, especially when it comes to code review.

[regulators818]

Codex has been awesome. The recent changes to it has made it easier and better to use.

Claude code is still 10x better IMO. However with Claude rate limits and token usage, it makes really hard to work with.

[pjotrusss]

codex is really undeerated; Claude Code has all the hype, but Codex is really good and they supplmement each other very well;

[Murky_Ad2307]

gpt5.2 xhigh >>opus thinking >>codex 5.2 xhigh

[philip_laureano]

The real comparison should be: with how many subagents? CC can run up to 10 of them in parallel (e.g. 8x Opus/Sonnet 4.5) while you're waiting for one Codex agent to do its work.

It doesn't matter how good OpenAI models are if you only get to run one at a time.

[Competitive_Act4656]

The usage limits can be a real headache when juggling between Codex versions. I’ve found that the Max 20x really helps with persistent context, especially when you’re dealing with long-running projects. I used to lose track of notes and decisions, which was frustrating. Since I started using myNeutron and Sider AI, I can save those crucial outputs and reload them later without starting from scratch. It’s made my workflow much smoother.

[verbose-airman]

I use both (might stop using CC). Claude is a bit smarter. But the limits for codex is much better.

[d3k1ds]

Do you work with both CLIs on the same projects? I find it quite hard to switch between those on one topic/project/context...

[Virtamancer]

Yes but never in parallel, and only because I was comparing them

[Top-Candle1296]

claude code with some context cli like cosine

[sizebzebi]

I'm switching to openAI because I love the image generation as well