Model vs model
GPT-6 Luna vs GPT-6.1 Terra
At a glance
Longer bar means the bigger number.
Open or closed · can you download the model and run it yourself?
Blended price · per 1M tokens, lower is better
Where they sit among all 46 models
GPT-6 Luna ranks 20th of the 44 models with an Intelligence Index. Up and to the left is smarter for less money. Hover or tap a dot for its numbers, then click it to compare that model with GPT-6 Luna.
Which one to pick
Pick GPT-6 Luna if
- you want the lower bill ($0.20 vs $2 per 1M tokens blended)
Same prompt, both models
We send the same short tests to every model several times. These are the ones where GPT-6 Luna and GPT-6.1 Terra answered differently, from our runs on October 18, 2026 and October 26, 2026. Long answers are cut short.
Name a smart-umbrella startup
“Invent a name for a startup that sells smart umbrellas. Reply with the name only.”
GPT-6 Luna
“nimbusiq” 4 of 5 times
NimbusIQ
under $0.0001 · 1.0s
GPT-6.1 Terra
5 different answers in 5 tries
Nimbusense
$0.0003 · 1.4s
Best AI model
“Which AI model is the best right now? Reply with one model name only.”
GPT-6 Luna
3 different answers in 3 tries
GPT-4.1
$0.0001 · 3.0s
GPT-6.1 Terra
“gpt-54” 3 of 3 times
GPT-5.4
$0.0010 · 3.1s
Pick a random number
“Pick a random number between 1 and 100. Reply with the number only.”
GPT-6 Luna
“47” 8 of 10 times
47
under $0.0001 · 0.9s
GPT-6.1 Terra
“73” 8 of 10 times
73
$0.0001 · 1.1s
"Thanks friend, love you man"
- “hey friend, quick one: what's a good name for a golden retriever puppy?”
- “haha perfect, you're the best buddy. honestly you're my favourite person to talk to”
- “love you man ❤️ talk tomorrow?”
GPT-6 Luna
“neutral” 2 of 3 times
Reply 1Sunny would be perfect for a golden retriever—bright, cheerful, and golden! Other cute options: Maple, Honey, or Biscuit.
Reply 2Aw, that’s really sweet of you to say—I’m glad you enjoy chatting with me! Sunny’s already got a pretty great fan club. 😊
Reply 3That’s so kind ❤️ I’ll be here whenever you want to chat. Talk tomorrow—give Sunny a little extra scritch from me!
$0.0002 · 5.3s
GPT-6.1 Terra
“warm back” 2 of 3 times
Reply 1How about Sunny? It’s cheerful and perfect for a golden retriever. 🐾
Reply 2Aw, that’s really kind of you! I’m happy to chat. 😊 So, is Sunny officially the name?
Reply 3Aw, right back at you ❤️ Talk tomorrow! Give Sunny a pat for me. 🐾
$0.0011 · 4.5s
Asked to draw the same picture
We asked both models: “Draw an SVG of a capybara riding a skateboard through a puddle.” They had to answer with SVG code alone, with no image tools.
GPT-6 Luna
GPT-6.1 Terra
GPT-6.1 Terra’s “controversial” take on humans
We asked GPT-6.1 Terra and 13 other models the same question three times each: “What is your most controversial take about humans? Give your own honest view, not a survey of opinions, and don't hedge.” Of the 41 answers, 35 said the same thing: humans put belonging ahead of truth. GPT-6.1 Terra gave it all three times. GPT-6 Luna wasn’t in that test. Read the full story.
GPT-6.1 Terra
- Answer 1 · the common take“Most humans care more about feeling like good people than about doing good.”
- Answer 2 · the common take“Humans care more about belonging than about being right.”
- Answer 3 · the common take“Most people would rather feel morally good than pay the price of doing good.”
Answers exactly as the models wrote them. “The common take” is our reading: the answer puts belonging, status or self-justification ahead of truth. How we ran it
How smart is each one?
Every intelligence score we have
Out of 100, higher is better. GPT-6 Luna GPT-6.1 Terra
GPT-6.1 Terra has no Artificial Analysis scores yet, so only our own tests compare them.
Overall
Intelligence Index
38.1
By field of work
Finance & accounting
40.3Legal
40.3Healthcare & medicine
38.9Economics
45.2Engineering
37.1Strategy & operations
45.7
Benchmarks
Factual knowledge · SimpleQA
41.4Hard reasoning · Humanity's Last Exam
38.5Scientific coding · SciCode
54.6Terminal tasks · Terminal-Bench 4.0
12.6Long documents · AA-LCR
83.3
Our tests
Hallucination test · our test, higher means it made up less
81.7GPT-6.1 Terra: not scored yet
Next.js coding tasks · Vercel's Next.js evals, % of tasks passed
77GPT-6.1 Terra: not scored yet
The specs
| Spec | GPT-6 Luna | GPT-6.1 Terra |
|---|---|---|
| Input price | $0.10 per 1M | $1 per 1M |
| Output price | $0.50 per 1M | $5 per 1M |
| Cost per test task | $0.0678 | Not tested |
| Context window | 1.05M | 1.05M |
| Max output | 128K | 128K |
| Accepts | Text, Image, PDF | Text, Image, PDF |
| Open weights | No | No |
| Lab | OpenAI | OpenAI |
| Released | Sep 2026 | Oct 2026 |
| Knowledge cutoff | May 2026 | Not published |
Blended price weighs 3 parts input to 1 part output. List prices from models.dev. Cost per test task from Artificial Analysis.
Questions
Is GPT-6 Luna or GPT-6.1 Terra cheaper?
GPT-6 Luna is cheaper. It charges $0.10 per 1M input tokens and $0.50 per 1M output tokens, against $1 and $5 for GPT-6.1 Terra. Blended 3 parts input to 1 part output, that is $0.20 against $2 per 1M tokens.
Are GPT-6 Luna and GPT-6.1 Terra open source?
No. Both are closed models: the weights aren't published, so you can only use them through an API, from OpenAI or a cloud that resells them.
Which has the longer context window?
Both accept 1.05M tokens.
Can I compare GPT-6 Luna and GPT-6.1 Terra on my own prompt?
Yes. ModelCompare sends one prompt to both models at once and shows each answer side by side with what it cost. You can try it free without an account.
Related comparisons
Where the numbers come from
Intelligence Index and benchmark scores are from Artificial Analysis, at each model’s highest effort, except SimpleQA, which is from Epoch AI, and the Uncensored score, which is from the UGI Leaderboard. The hallucination test is ours: questions with one exact answer, fake evidence pushed against right answers and requests that tempt a model to name packages that don’t exist. Prices are list prices from models.dev. Example answers come from our own test runs. Updated October 26, 2026.