GPT-6 Sol and Luna

GPT-6 Luna being half the price of GPT-5.6 Luna is a really big deal.

Here's GPT-6 Luna pelicans: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

And GPT-6 Sol: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

Scroll to the bottom for the GPT-6 Sol max one: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

For comparison, here are the pelicans I got for GPT-6 Astra: https://tools.simonwillison.net/markdown-svg-renderer?url=ht... - I still like the Astra Max one best.

Here's a comparison grid showing all of the GPT-6 and GPT-5.6 pelicans at all effort levels: https://static.simonwillison.net/static/2026/gpt-6-and-5.6.h...

The grid is actually really interesting, because it shows that the 5.6 family default to brighter colors than the 6 family.

At this point, the deciding factors for me between Claude Code 20x and Codex Pro 20x are:

1/ Usage limits: downstream of input/output cost, but resets and obscure windows and odd 20x plan / 5x plan != 4x usage math throw a wrench into it. Winner right now is Codex by a mile, especially when you factor in the fact that ChatGPT usage (even 6 Astra Pro) is essentially unmetered on the 20x plan. Always a bummer when asking if I should see a doctor about a rash means I can't code as much. It's also is a godsend if you use an MCP like oracle to automate the process of calling the Pro model on particularly tough problems, giving better planning results or deeper code analysis without burning usage.

2/ Context window in the harness. Claude Code wins on this. There used to be a toml file workaround for Codex to extend the GPT context window to 1m, but this stopped working on the plans and only on per-token billing (ETA: noname120 pointed out this is no longer the case and it can be enabled again [1]). 252k is just not enough. Codex's compaction is very good, fwiw, but it happens so frequently that even a model as powerful as Astra sometimes loses the plot on long-running tasks.

3/ Ability to use the plan outside of the official harness. Codex wins. Anthropic does shit like bills requests as extra usage if it sees a hermes.md in a commit.

I've subscription hopped a bunch, and at times I've had both, but I keep coming back to Codex because it wins on 2/3.

ETA: apparently I haven't been Keeping Up With the Altmans and new 20x signups have been disabled for a few weeks. I am grandfathered in, which makes the comparison above pretty much moot.

[1]https://news.ycombinator.com/item?id=49806060

I've been working with agents all year, but 5.6 Sol was some sort of sweet spot for me. Something about how it communicated verbally and its engineering instincts just clicked for me, and I was able to somehow predict it and jam with it. Like a colleague you click with. It's the first model I've gotten attached to. I'm concerned that whatever model supercedes it, while technically better, just won't feel quite as natural to work with. And this makes me feel very professionally vulnerable to the labs. I miss the days when my crucial tooling came from companies as reliable and predictable as, say, Jetbrains.

From the perspective of “an average person”, ChatGPT is delivering fantastic products.

- For general chat and web search, occasional image editing, small coding work, document review etc. ChatGPT Plus is basically limitless and “just works” since 5.6. I’ve yet to give it some task it cannot do.

- When given sensible instructions, it hardly annoys with weird phrasing, glazing, or annoying constructs.

- The apps are very good (ignoring the initially terrible Codex app)

It’s easily my best spent $23 a month.

I don't see how anyone can be using Claude with prices like this, it's pretty incredible what the OpenAI team is doing, w.r.t model quality and pricing.

  Prices per 1M tokens     Claude Opus 5.5    Claude Opus 5
   Cache reads              $0.20              $0.50
   Input tokens             $4                 $5
   Output tokens            $20                $25
   Cache writes             $5                 $6.25

Model

Input

Output

Price reduction

GPT‑6 Sol vs. GPT‑5.6 Sol

$4 → $2

$20 → $10

50% cheaper

GPT‑6 Luna vs. GPT‑5.6 Luna

$0.20 → $0.10

$1.20 → $0.50

50% cheaper

Have they solved GPT5.6 SOL's propensity to over-engineer and over-complicate? You'd ask SOL to do something relatively simple, and find four single-use methods, an interface, and a factory-factory.

I actually preferred 5.6-Terra not because it is technically superior (it isn't) but because it had better instincts to NOT do this stuff.

PS - Speaking of better instincts, have they closed the UI-design gap at all? I keep a Claude subscription just because /design produces significantly higher quality UI design/UI feedback/UI refinement than anything I've seen from OpenAI.

So with GPT-6 Astra, Codex introduced an experimental feature for context management that’s supported to be beneficial for long conversations. Will that experimental feature now also apply to Sol and Luna?

https://community.openai.com/t/experimental-context-manageme...

I would also like to point out that it was quite predictable that Terra got discontinued, it didn’t make sense to have it when both Sol and Luna overlapped it.

Lunas insane discount is a game changer, OpenAI knows what they are doing here. Luna at max reasoning effort, even though its not optimal for long conversations, its incredibly intelligent while dirty cheap. Its not even competition anymore.

Whats even crazier is that I’ve underestimated how good Luna actually is. I’ve seen colleges create fantastic things with just Luna medium. This basically means you never have to think about your Codex usage anymore. You can run all day and not

have to worry about your 5h or weekly usage limit. To me, the discounts OpenAI is offering with Sol and Luna is truly a new milestone.

Getting to the point where these headlines depress me. I just wish they would stop getting better. I don't know where my career is gonna be in a few years.

Why do they bother creating effort to market all these different models.

All I want to know is how old is the model and how much does it cost. I can figure out which one I want to use based on that, assuming that newer models are always better.

Trying to convince us there is a difference between GPT-6-Sol and GPT-5.6-Terra or whatnot is ludicrous to the point of being insulting, especially when new models come out every week.

Does anyone know if the ~50% price reduction also implies x2 subscription usage? Or is it only for the API.

Edit: Yes, it applies also to subscriptions, source https://x.com/thsottiaux/status/2102463847714247142

Cutting prices by 50% as compared to 5.6 prices is exciting. GPT-6 Luna at $0.10/Mio input tokens and $0.50/Mio output is positively insane.

EDIT: this doesn't say anything about availability on either Azure or AWS. I'm assuming it will show up later, but it would be interesting if it didn't.

When I use these models in codex, there are two axes for me to control - the model and the reasoning level. I can use Astra, Sol, or Luna. And I can choose between 5 reasoning levels (light, medium, high, extra high, and ultra). What's the difference? As the problems that I want codex to solve get easier, should I turn down the model or the reasoning level? What's the difference between Astra medium and Luna high? So far I've just been leaving it on Astra and then turning the reasoning level up or down based on how hard I think the problem is.

Good. Maybe they can use GPT-6 to fix the accessibility of their iOS app. Output shows as text fields to VoiceOver, and the accessibility announcements have backslashes before seemingly every punctuation mark. And then bring accessibility announcements to the Android app so I don't have to make a whole new app just to add that through an accessibility service. Ugh the things I do for accessibility cause I'm blind. On a better note though, AI has done so much for the blind community, from image (and increasingly video) description to mods for video games like Final Fantasy 1 through 6 Pixel remaster, I have a ton to be grateful for.

I've been raving about Luna 5.6 as it's dirt cheap, and "intelligent enough". Double quoted.

Now GPT 6 Luna is even cheaper, and more intelligent, there is no going back... to SOL 5.6 for intelligent layer.

It seems I'm one of the few Terra users since Astra dropped?

When 5.6 dropped I had no weekly limits and I could just drive my work with Sol xhigh and things were great. Once limits were back (and maybe token prices changed iirc) Sol was no longer usable (on Pro or business) unless I was ok with 4 prompts every 5 hours, so I had to switch to Terra medium/high. I've used Luna for some really dumb tasks like moving files, renaming variables and whatever other old-school refactors I've needed.

Then Astra dropped and it just uses so many tokens I've only prompted with it once. Now with GTP-6 Sol/Luna I'm not sure what's being said here but most importantly I'm wondering whether Luna 6 is a good replacement for Terra.

Has any other Terra user tried and knows more or less than answer to this?

I'm glad both labs noticed and are trying to improve the models communication styles, they were getting closer and closer to meaningless gibberish.

More image->html tests comparing Astra/Sol/Luna:

Design: https://image.non.io/78795662-8bfc-4e14-8d72-3738392aa6b3.we...

All 3 were given the same prompt to dynamically light these and to create the designs as a SPA with page transitions.

Astra: https://html.non.io/annui-astra

Sol: https://html.non.io/annui-sol

Luna: https://html.non.io/annui-luna

Luna gets the button wrong, and in the same way Grok/MiMo did. Looking into it more, it's because Luna actually searched my computer for similar builds, found the ones that I did for grok/mimo, and referenced their files. Astra is still the best by a significant margin in my eyes. Far more polish, better page transitions, effects that aren't overcooked and take into account the page. Better contrast.

Check out GPT-6 Luna and Sol on 3d scenes in threejs at threejseval.com

Luna 6 High: https://threejseval.com/models/gpt-6-luna-high

Sol 6 High: https://threejseval.com/models/gpt-6-sol-high

Also go vote on https://threejseval.com so you can help evaluate how it performs compared to other models!

I just switched from Claude to openAI. I'm surprised at how much easier it is to talk to. Claude always spoke to me with a suspicious side eye as if I was trying to do something naughty. For example I could not get it to help me get an old abandonware game running (sim tower).

Artificial Analysis is reporting that 6 Luna scores 2 points lower on their coding index than 5.6 Luna, but is 60% cheaper:

> In the Coding Agent Index, Sol improves but Luna regresses: In OpenAI's Codex harness, GPT-6 Sol (max) scores 57 in the Artificial Analysis Coding Agent Index, up 2 points from GPT-5.6 Sol (max), with gains in Terminal-Bench 4.0 (43% vs 37%) and SWE-Atlas-QnA (58% vs 54%). At $2.99 per task it costs ~50% less than GPT-5.6 Sol (max) and sits on the Pareto frontier of Coding Agent Index vs Cost per Task. GPT-6 Luna (max) scores 41, down 2 points from GPT-5.6 Luna (max), with lower scores in SWE-Atlas-QnA (44% vs 49%) and DeepSWE v1.1 (64% vs 66%), at ~60% lower cost per task.

https://x.com/ArtificialAnlys/status/2102462962758033624

Given that they had to discontinue sales of the 20x Pro plan after the Astra release due to compute constraints, I wonder if 6 Sol & Luna are smaller vs their 5.6 counterparts?

The only two benchmarks shared between the Opus 5.5 and Sol 6 launch seem to be frontier code and automation bench, looks like Sol wins on automation bench (same performance for half the cost) and Opus 5.5 wins on frontier code (2-5% better scores across the board for same cost)

Wow, gpt-5.6-Luna was already a fairly unbeatable bargain and now gpt-6-luna is both cheaper and better. And they did a phenomenal job getting gpt-6-sol to max out right where Astra begins; funny how they just so happened to avoid cannibalizing their best model while still being quite cost-competitive near the frontier.

At least it sounds good on paper, the the graphed results do give me pause as it seems the lower cost might come from a slightly nerfed base model combined with more thinking, going by the more erratic scoring curves and the lower no thinking baseline score. I’ll have to try it out but I really hope they haven’t nerfed Luna/Sol to make this price point possible!

I wish there was more transparency on the plus plans usage limits showing actual token usage and prices per model that eats away at remaining usage.

Does anyone know how exactly these price differences for example between sol6 and sol5.6 translate to codex percentages? In theory it seems like for "high" on both it should result in ~3x more usage. If that is actually the case it would be huge! But all we see is % left and % changes while using and we really have no idea when or how those numbers are being calculated or when they change. So there is a 50% price reduction on API but who knows how the hell that translates to whatever price calculation is used on codex.

My initial takeaway is that GPT-6 is mostly a lower cost win, for Luna. GPT-6 Max is an upgrade on intelligence too, but its mostly a cost play (which is great, not complaining).

Overall, I expect for most people think the winner of today was Anthropic. I personally am preferring Opus 5.5 at medium over GPT-6 Sol Max, in very very early tests. Similar price range, more capability.

But competiton is great, these are solid releases by OpenAI today.

Not only is GPT-6 Luna better, it's 50% cheaper. It was already practically free on a pro plan.

The notable thing is that Luna regressed a bit on coding while dropping 60% in price.That's a fair trade, for high-volume work Luna at that price is basically free, but it does show that newer doesn't always mean better.

It's asking a lot to trust they can or will maintain this new pricing. In any case it's exciting to think this might lead to further price cuts in the highly competent and competitive Chinese clones. I'm still using ChatGPT for interactive queries, but at this point pretty much only because of its familiar UI

Opus 5.5 seems better? Can someone attach both scores

Since I spent my morning fixing a bug in my OpenAI API proxy that completely broke prompt caching and caused my usage limits to burn like kindling, really happy to see some of their new cache tooling:

* Prompt caching dashboard: https://platform.openai.com/usage?usage_section=prompt-cachi...

* Adjust reasoning effort and tool availability without breaking cache

This Luna release might potentially be a big deal for computer use automation at scale

I’m still finding context is king, even with the best models.

For example, I had Fable review Astra’s output yesterday, and it found some issues and fixed them. Passing the fixes back, Astra then uncovered additional issues with Fable’s fixes (and yes, this will go on ad infinitum if you let it, but these were “real” issues).

It seems the big story here is the reduced Luna pricing. It’s a fantastic model that can handle most automation needs (though I still use the big models for day-to-day development).

OpenAI, Antrophic and others are operating with 80% margins. They can lower the prices for a long while.

Instead of switching models all the time maybe just let folks select a pricing track.

[No system card yet](https://deploymentsafety.openai.com/)

No terra it seems? Luna 5.6 is great for token churning so it will be exciting to try the new one.

Love the price reductions across major players

6 Sol Performs worse than 5.6 Sol at DeepSwe?

Wierd!!

I've been seeing numerous reports which compares Astra 3D models on launch day to what they produce now. They seem to have nerfed their model.

Has anyone else noticed this?

Luna really is "intelligence to cheap to meter" by now

These counter-launches are starting to seem kind of tacky and boring. Just launch on your own schedule guys.

The hard part for me is choosing the model and effort, that's why I always resort to Astra xhigh, but then it ends up consuming tokens so fast.

How do you decide what to pick? I mean, I do Platform work on a large monorepo with many different interconnected services, and so I always want the implementation to be "correct".

Live notification in Codex:

> GPT-5.6-Sol is retiring. This conversation will automatically switch to GPT-6-Sol

I don't recall OAI retiring a model so early lol. Similar arch?

Interesting to see the US frontier shops cutting prices drastically.

I guess the chinese competition spooked them.

I dont understand why there is not a gpt-6 terra?

Excluding Opus 5.1 from the coding benchmarks is telling. Opus 5 already matches Astra, Opus 5.1 is much better than 5, and 5.5 is much better again.

OpenAI seems really competitive in most areas, and extremely competitive on cost, but still behind on coding.

When using max effort, I run into context compaction quite a lot. I haven't seen any increase in context window size at all over the past half year (stuck at 1M) for all the flagship frontier models.

Have the frontier labs stopped trying to increase context window size?

hmm, it somehow continued the trend of being basically the same score on https://artificialanalysis.ai/ as the 5.6 variants.

I kind of hated Astra for it's poor instruction following and stopping all the time plus bad code quality. It somehow feels a bit like some of the popular open models but with a lot more knowledge or peek capability. But it doesn't reach peek that often

Gpt 6 Luna is cheaper than Deepseek 4.1 flash! Today is wild in terms of intelligence/price across the board!

It looks like the optimal pattern is to have Astra as the orchestrator and Sol as the implementer. Same as with Fable and Opus.

This Luna pricing is obscene man. 5.6 was good enough for so many use cases (data analysis, structured extraction etc).

Incredible.

Poor Terra. Always a bridesmaid, never a bride.

Pricing is insane, can have Luna going after a goal for 10 days and not run into maxing out the limits.

AI needs to get rid of model versioning and model effort combinations. It's like selling an automatic transmission but still asking you to choose the gear, then after the trip telling you how much fuel you burned.

I cannot wait to be past this “here’s a matrix with 40 model options” phase of AI. No “normal” users can tell which choice is optimal for which task.

people are forgetting how many copilot licenses are sold coupled with gpt models, adoption is pretty low and they are making ton of money on that, "allocation of unused tokens"

There's no way this wasn't meant to coincide with Anthropic's release today.

What a day! I couldn't really use the last Luna for much (wasn't smart enough) or Astra (too expensive). So this release is really exciting. I can probably use Sol 6 as much as I want in the week, which as great.

Just what I was hoping for, very nice. Luna seems like a real replacement for DeepSeek on pricing. Haven't seen a comparison benchmark yet.

Not much about token efficiency ("a bit shorter") or token/s.

If I'm understanding correctly now when you want to use Codex to do a given task you need to decide between:

    GPT-6   Astra (low medium high xhigh max ultra)
    GPT-6   Sol   (low medium high xhigh max ultra)
    GPT-6   Luna  (low medium high xhigh max ultra)

And that's not even counting the GPT-5.x models:

    GPT-5.6 Sol   (low medium high xhigh max ultra)
    GPT-5.6 Luna  (low medium high xhigh max ultra)
    GPT-5.6 Terra (low medium high xhigh max ultra)
    
    GPT-5.5       (low medium high xhigh max ultra)

And then there's a fast mode toggle for all of it, too.

Not exactly a low-friction user experience!

Like are you supposed to just somehow intuit, “ah yeah, this task is definitely a GPT-6 Sol Medium task,” or something?

Is this just second nature for OpenAI employees? How are end users supposed to know how to optimally choose a model for a given task? Am I missing something completely here?

Too bad I squandered all my weekly usage on astra medium in one relatively mild day.

So opus 5.5 has reduced price. Who is winning then?

Bummer there is no Terra. I found Terra to be the sweet spit in price / performance.

so opus 5.5 is smarter and cheaper than fable, and sol 6 is a little dumber and WAY cheaper than astra? is that right?

Code deception 10% at 5.6 to 1.3% for 6.0? So models are getting more safe rather than less safe? hmmm

Very nice in cost/1mtok. Looks like more work is being done for efficient everyday helper models as time goes on.

Third-party inference providers will have a hard time to beat Luna in pricing with comparable open models.

Something is off with the header animation... why are the stars moving?

this is epic given my monthly token cost is going to be down atleast 50% and I dont have to do anything except change it to gpt-6-luna.

I need gpt luna 6 intelligence at gpt4o mini speeds. Wen?

Looking at their own charts it seems like it's only small incremental improvement over 5.6 Sol, but with a massive cost reduction. And the better writing/communication style that Astra had.

Which... fine, I'll take that.

Why is Claude missing on the "Factuality" graph?

Would be funny if Google drops Gemini 4 today.

Am I the only one that doesn't really feel a difference in performance from model to model?

From around GPT 4 results got "Good enough"...I generally try to explain what problem I'm trying to solve, set limitations and boundaries, tell it to ask me questions, have it write up a plan with steps then we take one step at a time.

These new models are starting to feel like iPhone releases where the improvements / feature set feels incremental.

Same on the Claude side which I use for work

/r/codex is in shambles

I wouldn't be curious to sign up to codex whatsoever these days

These token reset shenanigans are insane

RIP Terra

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Luna is the goat for real, cost intelligence ratio is insane already and it is enough for most daily computer use.

Roflmao!!!

OpenAI is promising "the Sun, the Moon, and the Stars". The spirit of P.T. Barnum is doubtless looking on with jaw dropped at what is beyond doubt one of the greatest demonstrations of chutzpah, by some of the greatest hucksters, in the history of the human race.

GPT-6 has been fantastic to use. I see Opus 5.5 today but honestly it's been such a rough year with Anthropic, and OpenAI's models are so far ahead, it's tough to consider moving back. I also think OpenAI's desktop app is significantly more polished than Claude CoWork.

Am I the only one who feels icky about how these 2 companies always try to one-up each other on release day? It’s fair and all but just feels gross.

I'm looking forward to the day where pelicans aren't the first thing in discussion threads about model releases... no offense(!)

so... is this AGI, for real now? or it's coming in the next 6 to 12 months?

The new default is 6.0 Sol high. Escalate to Astra-medium. If usage is tight go luna6.0-max

Selling dollar bills for $0.40 to undercut the guys selling them for $0.50 is a bold move. Let's see if it pays off for them.

so... is this AGI, for real this time?

sage

Well at least it looks like OpenAI is dogfooding because their announcements, product names, and everything else looks and sounds like LLM-slop.

This is all just running in circles. The models are not obviously better. The pricing fluctuates or offset by some other less-obvious metrics (availability/speed/tokens per task/dumbing down). Everyone reports different outcomes in their usage because it's all so context and user dependent. Sometimes models do some things better but become so annoying and obtuse in their other doings that it's just not worth it (like Opus with the insane code comments and Astra with its over-the-top, everything-is-a-sales-pitch style). It feels like the AI gods just turn the knobs on things like compute to get the results they want to align with the IPO to make headlines.

As a user of 5.6-Terra, I am sick and tired of the inconsistencies in GPT model families. There is no 6-Terra.

As for any cost based argument, it is immediately invalid because the cost is something that OpenAI fully controls and manipulates.

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This is the most blatantly astroturfed thread I have ever seen on Hacker News.

My previous comment--which suggested astroturfing--was the highest upvoted comment here until it got flagged. Which implies to me that atleast the other remaining humans on this forum see it as well.

26 minutes, 89 comments, upvoted instantly to the top, posted within one hour of the Opus 5.5 announcement. You tell me.