GPT-6.1 Terra

I'm very confused about their model market position/naming schema.

First we had:

> Luna (Small), Terra (Medium), Sol (Big).

Which was fairly smooth after you got used to their planets.

But then they added Astra as the "Bigger," which was mostly still self-coherent:

> Luna (Small), Terra (Medium), Sol (Big), Astra (Bigger)

But then things go confusing, they released Sol-6.1 which sometimes is superior to Astra, and discontinued Terra which made it look like this:

> Luna (Small), Sol-6.1 == Astra

But with Sol-6.1 costing the old Terra-6.0 price, while, as I said performing as good as the old "Bigger" model in many non-3D/UI situations.

Now they're re-introduced Terra, as a 6.1 release, making this even more confusing.

Did Microsoft's chief branding officer move over to OpenAI?

Pelicans for GPT-6.1 Terra: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

Interesting that both "none" and "low" reasoning levels appeared not to spend any reasoning tokens at all, and in fact low ended up using less tokens and costing less than none here.

"medium" did use 496 reasoning tokens, but that's apparently not enough here to return a visible reasoning trace.

OpenAI's current frontier model lineup is gpt-6-astra, gpt-6.1-sol, gpt-6.1-terra, gpt-6-luna, so here's a comparison grid of all of their pelicans at different reasoning levels: https://static.simonwillison.net/static/2026/openai-pelicans...

Can anyone give me the compelling reason for Terra and Sonnet to exist?

Virtually every task I give to either is better served by going up a tier and down a reasoning level, or down a tier and up a reasoning level. I simply don't understand their use case. No testing I've done has shown them to have a niche where there isn't a cheaper-with-equal-results or more-performant-at-same-cost option.

Similar 75% price cut trajectory as GPT-5.6 Sol -> GPT-6.1 Sol. Overall, Terra is still half the price of Sol.

But like the original release of Terra, it's still a weird middle child between the small-model-that-got-substantially-better (Luna) and the large-model-that-got-significiantly-cheaper (Sol). The TerminalBench 4.0 cost-per-task results are a bit confusing and I'm not sure why you would pick Terra over Sol in that case. Overall this release seems like a flex on Sonnet 5.5: a model which is having its own middle child problems between the godly Opus 5.5 and the surprisingly capable Haiku 5.5.

Why do Anthropic and OpenAI think it necessary to split their model into 4 versions (Opus, Sonnet, Fable, Haiku, Astra, Sol, Luna, Terra) vs. Google's 2 (Argon, Flash)?

  GPT-6 Astra
  Input:$10.00 / 1M tokens Cached input:$1.00 / 1M tokens Output:$50.00 / 1M tokens
  
  
  GPT-6.1 Sol
  Input:$2.00 / 1M tokens Cached input:$0.10 / 1M tokens Output:$10.00 / 1M tokens
  
  
  GPT-6.1 Terra
  Input:$1.00 / 1M tokens Cache read:$0.05 / 1M tokens Output:$5.00 / 1M tokens
  
  
  GPT-6 Luna
  Input:$0.10 / 1M tokens Cached input:$0.01 / 1M tokens Output:$0.50 / 1M tokens

(For some reason they say "Cache read" instead of "Cached input" for 6.1 Terra)

6.1 Astra and 6.1 Luna must be coming up soon. Will they reduce their prices further?

Still can't really forgive any of them for essentially stealing most of this knowledge regardless...

I rather enjoy OpenAI's focus on cost-per-task.

I'm optimistic about them tackling frontier intelligence next. Astra 6.1 please?

OpenAI repeatedly keeps hurting user workflows by altering the model generations family for each new version in unpredictable ways. As such, it is not a sane ecosystem to develop in.

cool update. Like super cool.

Just one thing about the advert, how can I be the only person here thinking the ad is weird - like for the marketing dep, its a bit weird the ad features the same tram that broke and tragically like ended some people - happened for like the first time ever in 100 years, like a year ago ( 14 months ago) just a bit weird.

Im honestly not trying to be negative, but its kinda weird I kinda feel I should mention it because noone else has?

Im sure literally anyone from southern europe must have thought this the second they saw the ad. It was big news last year.

Am I mad? Just a heads up for PR to always check things like this first when releasing a video? Maybe its just me? Just trying to help

Wow. If those charts are true, this effectively matches GPT-6-Astra at a fraction of the cost, and is neck-and-neck with 6.1-Sol.

This tier is what I'd actually point opencode at for PR reviews. The top models are too slow and expensive to run on every diff.

The results for factual error rate on "difficult" prompts is staggering to me. Particularly the difference between 5.6-Terra and 6.1-Terra. These are wildly different Pareto fronts. Our custom enterprise agent is currently running on 5.6-Terra and it's already very good. I look forward to updating the configuration.

I'll wait for the runebench results!

On AA intelligence index, this fills in the cost per task frontier nicely between 6 Luna and 6.1 sol. So when 6.1 Luna inevitably releases...

The OAI model tango seems to not have an end in sight, for better or worse. Give me more API toys!

Am I reading the Agents’ Last Exam v1 graph correctly where it's saying GPT Luna Medium performs better than High, but XHigh is better than Medium?

These "Pareto frontier" performance vs price graphs have become very popular and I find them mostly uninformative. Pricing is subjective. You chose the position on the X axis, and which measures to use on the Y Axis.

I am wondering if there is a site with a perf/efficiency chart of the models over time? I am wondering is the pace still speeding up?

They say it has "A significant step up on factuality and coding". My browser is underlining "factuality" in red. AI hallucinations or hallucinatiality are still a big problem in my experience.

Sell it to me. Why would I ever give money for this?

https://artificialanalysis.ai/#intelligence-efficiency-tabs

According to this, Sol 6.1 x-high is both cheaper and smarter than Terra 6.1 max.

GPT-6 only just came out! The AI landscape is always on the move!

i'm not sure anyone cares about Terra though.

Previous Terra model was so good it was discontinued.

OpenAi needs a model to compete with Opus 5.5, and that's not Terra 6.1.

Underwhelming

Is it stronger and cheaper than DeepSeek V4.1 Flash 1017?

If not, yawn...

Really hate how they only show it vs Opus @ Max and not Low/Medium/High.

The benchmarks are already saturated and the curves for Terra stick to the axes.

People keep asking OpenAI for a mode that's as good as Opus 5.5, and they release this instead. Interesting strategy. Let's see how it works out for them.

"better writing"

let's see if it can pass the Pangram test. Many services purport to fool it, but fail.

That terminal bench 4.0 result is... bad? Terra XHigh more expensive than Sol Low and still does worse.

It's very likely this is a next checkpoint of GPT-6 "Sol", over-optimised for the web chat and offered to Codex subscribers as a "please go away" offering.

If this was half the price, I'd be very interested, but at 1/5/0.05? Feels like another panic release because they can't get Astra 6.1 out of the door...

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If they had any courage, they would release 6.1 Astra, but they don't.

Update: Look at the OpenAI employees downvoting me.