GPT-5: Key characteristics, pricing and system card

258 Philpax 81 8/7/2025, 5:46:18 PM simonwillison.net ↗

Comments (81)

morleytj · 1h ago
It's cool and I'm glad it sounds like it's getting more reliable, but given the types of things people have been saying GPT-5 would be for the last two years you'd expect GPT-5 to be a world-shattering release rather than incremental and stable improvement.

It does sort of give me the vibe that the pure scaling maximalism really is dying off though. If the approach is on writing better routers, tooling, comboing specialized submodels on tasks, then it feels like there's a search for new ways to improve performance(and lower cost), suggesting the other established approaches weren't working. I could totally be wrong, but I feel like if just throwing more compute at the problem was working OpenAI probably wouldn't be spending much time on optimizing the user routing on currently existing strategies to get marginal improvements on average user interactions.

I've been pretty negative on the thesis of only needing more data/compute to achieve AGI with current techniques though, so perhaps I'm overly biased against it. If there's one thing that bothers me in general about the situation though, it's that it feels like we really have no clue what the actual status of these models is because of how closed off all the industry labs have become + the feeling of not being able to expect anything other than marketing language from the presentations. I suppose that's inevitable with the massive investments though. Maybe they've got some massive earthshattering model release coming out next, who knows.

thorum · 35m ago
The quiet revolution is happening in tool use and multimodal capabilities. Moderate incremental improvements on general intelligence, but dramatic improvements on multi-step tool use and ability to interact with the world (vs 1 year ago), will eventually feed back into general intelligence.
darkhorse222 · 3m ago
Completely agree. General intelligence is a building block. By chaining things together you can achieve meta programming. The trick isn't to create one perfect block but to build a variety of blocks and make one of those blocks a block-builder.
hnuser123456 · 56m ago
I agree, we have now proven that GPUs can ingest information and be trained to generate content for various tasks. But to put it to work, make it useful, requires far more thought about a specific problem and how to apply the tech. If you could just ask GPT to create a startup that'll be guaranteed to be worth $1B on a $1k investment within one year, someone else would've already done it. Elbow grease still required for the foreseeable future.

In the meantime, figuring out how to train them to make less of their most common mistakes is a worthwhile effort.

belter · 1m ago
> Maybe they've got some massive earthshattering model release coming out next, who knows.

Nothing in the current technology offers a path to AGI. These models are fixed after training completes.

BoiledCabbage · 56m ago
Performance is doubling roughly every 4-7 months. That trend is continuing. That's insane.

If your expectations were any higher than that then, then it seems like you were caught up in hype. Doubling 2-3 times per year isn't leveling off my any means.

https://metr.github.io/autonomy-evals-guide/gpt-5-report/

morleytj · 34m ago
I wouldn't say model development and performance is "leveling off", and in fact didn't write that. I'd say that tons more funding is going into the development of many models, so one would expect performance increases unless the paradigm was completely flawed at it's core, a belief I wouldn't personally profess to. My point was moreso the following: A couple years ago it was easy to find people saying that all we needed was to add in video data, or genetic data, or some other data modality, in the exact same format that the models trained on existing language data were, and we'd see a fast takeoff scenario with no other algorithmic changes. Given that the top labs seem to be increasingly investigating alternate approaches to setting up the models beyond just adding more data sources, and have been for the last couple years(Which, I should clarify, is a good idea in my opinion), then the probability of those statements of just adding more data or more compute taking us straight to AGI being correct seems at the very least slightly lower, right?

Rather than my personal opinion, I was commenting on commonly viewed opinions of people I would believe to have been caught up in hype in the past. But I do feel that although that's a benchmark, it's not necessarily the end-all of benchmarks. I'll reserve my final opinions until I test personally, of course. I will say that increasing the context window probably translates pretty well to longer context task performance, but I'm not entirely convinced it directly translates to individual end-step improvement on every class of task.

oblio · 41m ago
By "performance" I guess you mean "the length of task that can be done adequately"?

It is a benchmark but I'm not very convinced it's the be-all, end-all.

jstummbillig · 1h ago
Things have moved differently than what we thought would happen 2 years ago, but lest we forget what has happened in the meanwhile (4o, o1 + thinking paradigm, o3)

So yeah, maybe we are getting more incremental improvements. But that to me seems like a good thing, because more good things earlier. I will take that over world-shattering any day – but if we were to consider everything that has happened since the first release of gpt-4, I would argue the total amount is actually very much world-shattering.

simonw · 42m ago
I for one am pretty glad about this. I like LLMs that augment human abilities - tools that help people get more done and be more ambitious.

The common concept for AGI seems to be much more about human replacement - the ability to complete "economically valuable tasks" better than humans can. I still don't understand what our human lives or economies would look like there.

What I personally wanted from GPT-5 is exactly what I got: models that do the same stuff that existing models do, but more reliably and "better".

morleytj · 15m ago
I'd agree on that.

That's pretty much the key component these approaches have been lacking on, the reliability and consistency on the tasks they already work well on to some extent.

I think there's a lot of visions of what our human lives would look like in that world that I can imagine, but your comment did make me think of one particularly interesting tautological scenario in that commonly defined version of AGI.

If artificial general intelligence is defined as completed "economically valuable tasks" better than human can, it requires one to define "economically valuable." As it currently stands, something holds value in an economy relative to human beings wanting it. Houses get expensive because many people, each of whom have economic utility which they use to purchase things, want to have houses, of which there is a limited supply for a variety of reasons. If human beings are not the most effective producers of value in the system, they lose capability to trade for things, which negates that existing definition of economic value. Doesn't matter how many people would pay $5 dollars for your widget if people have no economic utility relative to AGI, meaning they cannot trade that utility for goods.

In general that sort of definition of AGI being held reveals a bit of a deeper belief, which is that there is some version of economic value detached from the humans consuming it. Some sort of nebulous concept of progress, rather than the acknowledgement that for all of human history, progress and value have both been relative to the people themselves getting some form of value or progress. I suppose it generally points to the idea of an economy without consumers, which is always a pretty bizarre thing to consider, but in that case, wouldn't it just be a definition saying that "AGI is achieved when it can do things that the people who control the AI system think are useful." Since in that case, the economy would eventually largely consist of the people controlling the most economically valuable agents.

I suppose that's the whole point of the various alignment studies, but I do find it kind of interesting to think about the fact that even the concept of something being "economically valuable", which sounds very rigorous and measurable to many people, is so nebulous as to be dependent on our preferences and wants as a society.

GaggiX · 58m ago
Compared to GPT-4, it is on a completely different level given that it is a reasoning model so on that regard it does delivers and it's not just scaling, but for this I guess the revolution was o1 and GPT-5 is just a much more mature version of the technology.
techpression · 17m ago
"They claim impressive reductions in hallucinations. In my own usage I’ve not spotted a single hallucination yet, but that’s been true for me for Claude 4 and o3 recently as well—hallucination is so much less of a problem with this year’s models."

This has me so confused, Claude 4 (Sonnet and Opus) hallucinates daily for me, on both simple and hard things. And this is for small isolated questions at that.

squeegmeister · 28s ago
Yeah hallucinations are very context dependent. I’m guessing OP is working in very well documented domains
bluetidepro · 3m ago
Agreed. All it takes is a simple reply of “you’re wrong.” to Claude/ChatGPT/etc. and it will start to crumble on itself and get into a loop that hallucinates over and over. It won’t fight back, even if it happened to be right to begin with. It has no backbone to be confident it is right.
laacz · 8m ago
I suppose that Simon, being all in with LLMs for quite a while now, has developed a good intuition/feeling for framing questions so that they produce less hallucinations.
simonw · 8m ago
What kind of hallucinations are you seeing?
drumhead · 3m ago
"Are you GPT5" - No I'm 4o, 5 hasnt been released yet. "It was released today". Oh you're right, Im GPT5. You have reached the limit of the free usage of 4o
hodgehog11 · 1h ago
The aggressive pricing here seems unusual for OpenAI. If they had a large moat, they wouldn't need to do this. Competition is fierce indeed.
FergusArgyll · 34m ago
They are winning by massive margins in the app, but losing (!) in the API to anthropic

https://finance.yahoo.com/news/enterprise-llm-spend-reaches-...

ilaksh · 55m ago
It's like 5% better. I think they obviously had no choice but to be price competitive with Gemini 2.5 Pro. Especially for Cursor to change their default.
impure · 56m ago
The 5 cents for Nano is interesting. Maybe it will force Google to start dropping their prices again which have been slowly creeping up recently.
0x00cl · 1h ago
Maybe the need/want data.
impure · 57m ago
OpenAI and most AI companies do not train on data submitted to a paid API.
WhereIsTheTruth · 36m ago
They also do not train using copyrighted material /s
simonw · 8m ago
That's different. They train on scrapes of the web. They don't train on data submitted to their API by their paying customers.
daveguy · 27m ago
Oh, they never even made that promise. They're trying to say it's fine to launder copyright material through a model.
dr_dshiv · 1h ago
And it’s a massive distillation of the mother model, so the costs of inference are likely low.
bdcdo · 1h ago
"GPT-5 in the API is simpler: it’s available as three models—regular, mini and nano—which can each be run at one of four reasoning levels: minimal (a new level not previously available for other OpenAI reasoning models), low, medium or high."

Is it actually simpler? For those who are currently using GPT 4.1, we're going from 3 options (4.1, 4.1 mini and 4.1 nano) to at least 8, if we don't consider gpt 5 regular - we now will have to choose between gpt 5 mini minimal, gpt 5 mini low, gpt 5 mini medium, gpt 5 mini high, gpt 5 nano minimal, gpt 5 nano low, gpt 5 nano medium and gpt 5 nano high.

And, while choosing between all these options, we'll always have to wonder: should I try adjusting the prompt that I'm using, or simply change the gpt 5 version or its reasoning level?

mwigdahl · 1h ago
If reasoning is on the table, then you already had to add o3-mini-high, o3-mini-medium, o3-mini-low, o4-mini-high, o4-mini-medium, and o4-mini-low to the 4.1 variants. The GPT-5 way seems simpler to me.
vineyardmike · 17m ago
When I read “simpler” I interpreted that to mean they don’t use their Chat-optimized harness to guess which reasoning level and model to use. The subscription chat service (ChatGPT) and the chat-optimized model on their API seem to have a special harness that changes reasoning based on some heuristics, and will switch between the model sizes without user input.

With the API, you pick a model sizes and reasoning effort. Yes more choices, but also a clear mental model and a simple choice that you control.

impossiblefork · 1h ago
Yes, I think so. It's n=1,2,3 m=0,1,2,3. There's structure and you know that each parameter goes up and in which direction.
makeramen · 1h ago
But given the option, do you choose bigger models or more reasoning? Or medium of both?
paladin314159 · 1h ago
If you need world knowledge, then bigger models. If you need problem-solving, then more reasoning.

But the specific nuance of picking nano/mini/main and minimal/low/medium/high comes down to experimentation and what your cost/latency constraints are.

impossiblefork · 1h ago
I would have to get experience with them. I mostly use Mistral, so I have only the choice of thinking or not thinking.
namibj · 1h ago
Depends on what you're doing.
addaon · 1h ago
> Depends on what you're doing.

Trying to get an accurate answer (best correlated with objective truth) on a topic I don't already know the answer to (or why would I ask?). This is, to me, the challenge with the "it depends, tune it" answers that always come up in how to use these tools -- it requires the tools to not be useful for you (because there's already a solution) to be able to do the tuning.

wongarsu · 28m ago
If cost is no concern (as in infrequent one-off tasks) then you can always go with the biggest model with the most reasoning. Maybe compare it with the biggest model with no/less reasoning, since sometimes reasoning can hurt (just as with humans overthinking something).

If you have a task you do frequently you need some kind of benchmark. Which might just be comparing how good the output of the smaller models holds up to the output of the bigger model, if you don't know the ground truth

hirako2000 · 25m ago
Ultimately they are selling tokens, so try many times.
empiko · 3h ago
Despite the fact that their models are used in hiring, business, education, etc this multibillion company uses one benchmark with very artificial questions (BBQ) to evaluate how fair their model is. I am a little bit disappointed.
zaronymous1 · 1h ago
Can anyone explain to me why they've removed parameter controls for temperature and top-p in reasoning models, including gpt-5? It strikes me that it makes it harder to build with these to do small tasks requiring high-levels of consistency, and in the API, I really value the ability to set certain tasks to a low temp.
Der_Einzige · 1h ago
It's because all forms of sampler settings destroy safety/alignment. That's why top_p/top_k are still used and not tfs, min_p, top_n sigma, etc, why temperature is locked to 0-2 arbitrary range, etc

Open source is years ahead of these guys on samplers. It's why their models being so good is that much more impressive.

oblio · 38m ago
Temperature is the response variation control?
anyg · 2h ago
Good to know - > Knowledge cut-off is September 30th 2024 for GPT-5 and May 30th 2024 for GPT-5 mini and nano
falcor84 · 1h ago
Oh wow, so essentially a full year of post-training and testing. Or was it ready and there was a sufficiently good business strategy decision to postpone the release?
thorum · 20m ago
The Information’s report from earlier this month claimed that GPT-5 was only developed in the last 1-2 months, after some sort of breakthrough in training methodology.

> As recently as June, the technical problems meant none of OpenAI’s models under development seemed good enough to be labeled GPT-5, according to a person who has worked on it.

But it could be that this refers to post-training and the base model was developed earlier.

https://www.theinformation.com/articles/inside-openais-rocky...

https://archive.ph/d72B4

simonw · 6m ago
My understanding is that training data cut-offs and dates at which the model were trained are independent things.

AI labs gather training data and then do a ton of work to process it, filter it etc.

Model training teams run different parameters and techniques against that processed training data.

It wouldn't surprise me to hear that OpenAI had collected data up to September 2024, dumped that data in a data warehouse of some sort, then spent months experimenting with ways to filter and process it and different training parameters to run against it.

bn-l · 5m ago
Is that late enough for it to have heard of svelte 5?
bhouston · 1h ago
Weird to have such an early knowledge cutoff. Claude 4.1 has March 2025 - 6 month more recent with comparable results.
justusthane · 46m ago
> a real-time router that quickly decides which model to use based on conversation type, complexity, tool needs, and explicit intent

This is sort of interesting to me. It strikes me that so far we've had more or less direct access to the underlying model (apart from the system prompt and guardrails), but I wonder if going forward there's going to be more and more infrastructure between us and the model.

hirako2000 · 23m ago
Consider it a low level routing. Keeping in mind it allows the other non active parts to not be in memory. Mistral afaik came up with this concept, quite a while back.
diggan · 1h ago
> but for the moment here’s the pelican I got from GPT-5 running at its default “medium” reasoning effort:

Would been interesting to see a comparison between low, medium and high reasoning_effort pelicans :)

When I've played around with GPT-OSS-120b recently, seems the difference in the final answer is huge, where "low" is essentially "no reasoning" and with "high" it can spend seemingly endless amount of tokens. I'm guessing the difference with GPT-5 will be similar?

simonw · 1h ago
> Would been interesting to see a comparison between low, medium and high reasoning_effort pelicans

Yeah, I'm working on that - expect dozens of more pelicans in a later post.

ilaksh · 59m ago
This is key info from the article for me:

> -------------------------------

"reasoning": {"summary": "auto"} }'

Here’s the response from that API call.

https://gist.github.com/simonw/1d1013ba059af76461153722005a0...

Without that option the API will often provide a lengthy delay while the model burns through thinking tokens until you start getting back visible tokens for the final response.

ks2048 · 3h ago
So, "system card" now means what used to be a "paper", but without lots of the details?
simonw · 2h ago
AI labs tend to use "system cards" to describe their evaluation and safety research processes.

They used to be more about the training process itself, but that's increasingly secretive these days.

kaoD · 3h ago
Nope. System card is a sales thing. I think we generally call that "product sheet" in other markets.
nickthegreek · 2h ago
This new naming conventions, while not perfect are alot clearer and I am sure will help my coworkers.
pancakemouse · 1h ago
Practically the first thing I do after a new model release is try to upgrade `llm`. Thank you, @simonw !
simonw · 1h ago
efavdb · 1h ago
same, looks like he hasn't added 5.0 to the package yet but assume imminent.

https://llm.datasette.io/en/stable/openai-models.html

Leary · 3h ago
METR of only 2 hours and 15 minutes. Fast takeoff less likely.
kqr · 2h ago
Seems like it's on the line that's scaring people like AI 2027, isn't it? https://aisafety.no/img/articles/length-of-tasks-log.png
FergusArgyll · 29m ago
It's above the exponential line & right around the Super exponential line
qsort · 3h ago
Isn't that pretty much in line with what people were expecting? Is it surprising?
usaar333 · 2h ago
No, this is below expectations on both Manifold and lesswrong (https://www.lesswrong.com/posts/FG54euEAesRkSZuJN/ryan_green...). Median was ~2.75 hours on both (which already represented a bearish slowdown).

Not massively off -- manifold yesterday implied odds this low were ~35%. 30% before Claude Opus 4.1 came out which updated expected agentic coding abilities downward.

qsort · 1h ago
Thanks for sharing, that was a good thread!
dingnuts · 2h ago
It's not surprising to AI critics but go back to 2022 and open r/singularity and then answer: what "people" were expecting? Which people?

SamA has been promising AGI next year for three years like Musk has been promising FSD next year for the last ten years.

IDK what "people" are expecting but with the amount of hype I'd have to guess they were expecting more than we've gotten so far.

The fact that "fast takeoff" is a term I recognize indicates that some people believed OpenAI when they said this technology (transformers) would lead to sci fi style AI and that is most certainly not happening

ToValueFunfetti · 1h ago
>SamA has been promising AGI next year for three years like Musk has been promising FSD next year for the last ten years.

Has he said anything about it since last September:

>It is possible that we will have superintelligence in a few thousand days (!); it may take longer, but I’m confident we’ll get there.

This is, at an absolute minimum, 2000 days = 5 years. And he says it may take longer.

Did he even say AGI next year any time before this? It looks like his predictions were all pointing at the late 2020s, and now he's thinking early 2030s. Which you could still make fun of, but it just doesn't match up with your characterization at all.

falcor84 · 1h ago
I would say that there are quite a lot of roles where you need to do a lot of planning to effectively manage an ~8 hour shift, but then there are good protocols for handing over to the next person. So once AIs get to that level (in 2027?), we'll be much closer to AIs taking on "economically valuable work".
umanwizard · 2h ago
What is METR?
tunesmith · 2h ago
The 2h 15m is the length of tasks the model can complete with 50% probability. So longer is better in that sense. Or at least, "more advanced" and potentially "more dangerous".
isoprophlex · 1h ago
Whoa this looks good. And cheap! How do you hack a proxy together so you can run Claude Code on gpt-5?!
dalberto · 1h ago
Consider: https://github.com/musistudio/claude-code-router

or even: https://github.com/sst/opencode

Not affiliated with either one of these, but they look promising.

cco · 1h ago
Only a third cheaper than Sonnet 4? Incrementally better I suppose.

> and minimizing sycophancy

Now we're talking about a good feature! Actually one of my biggest annoyances with Cursor (that mostly uses Sonnet).

"You're absolutely right!"

I mean not really Cursor, but ok. I'll be super excited if we can get rid of these sycophancy tokens.

nosefurhairdo · 42m ago
In my early testing gpt5 is significantly less annoying in this regard. Gives a strong vibe of just doing what it's told without any fluff.
logicchains · 1h ago
>Only a third cheaper than Sonnet 4?

The price should be compared to Opus, not Sonnet.

cco · 30m ago
Wow, if so, 7x cheaper. Crazy if true.
onehair · 1h ago
> Definitely recognizable as a pelican

right :-D