GPT-6.1 Terra by OpenAI
About a quarter of Sonnet's cost for the same score. Test Sol next to it before you commit.
The pain: Your agent, extraction or triage feature runs on a mid-tier model, and on Claude Sonnet 5.5 it costs about $4 a task at the effort that reaches 50 on the independent index. Every new user makes that bill worse.
The fix: GPT-6.1 Terra scores 51 for $0.96 a task, at $1 / $5 per million tokens. It's on the OpenAI API, Bedrock and OpenRouter, but it has no Australian route, and its older sibling Sol beats it at the same spend.
What happened
On 26 October, OpenAI shipped GPT-6.1 Terra, the third step on its ladder: Astra at $10 / $50 per million tokens, Sol at $2 / $10, Terra at $1 / $5, Luna at $0.10 / $0.50. Its predecessor, GPT-5.6 Terra, cost $2 / $12. It's GA on the API, on Bedrock, in Copilot and on OpenRouter, with a 1.05 million token context. It isn't frontier: 51 on the Artificial Analysis index leaves it one point outside the top ten. I'm covering it because that's about where most production features live, and because this is the week the index moved to v5.
The numbers that matter
Scores and cost per task are from the Artificial Analysis leaderboard, index v5:
| Model and effort | Index v5 | Cost per task | Per million tokens |
|---|---|---|---|
| Terra (max) | 51 | $0.96 | $1 / $5 |
| Terra (high) | 42 | $0.26 | $1 / $5 |
| Sol (max) | 55 | $1.27 | $2 / $10 |
| Sol (medium) | 46 | $0.36 | $2 / $10 |
| Astra (medium) | 51 | $2.73 | $10 / $50 |
| Sonnet 5.5 (max) | 54 | $10.02 | $2 / $10 |
| Sonnet 5.5 (xhigh) | 50 | $4.09 | $2 / $10 |
| Sonnet 5.5 (high) | 41 | $1.64 | $2 / $10 |
Against Sonnet 5.5, the case is easy. Terra at max matches Sonnet at xhigh for about a quarter of the money, and Terra at high matches Sonnet at high for about a sixth. Close, not equal: Sonnet at max is still 3 points above anything Terra reaches, at ten times the cost.
Now the part OpenAI's price sheet hides. Sol costs twice as much per token and only 32% more per task at max, for 4 more points. So Terra must be burning about one and a half times the tokens (my inference from those figures). Further down, Sol at medium scores 46 for $0.36, and Terra needs xhigh to reach 45 for $0.40. At the same spend, the dearer model wins. Terra earns its place in high-volume work at the low end, where $0.26 a task is enough. If reliability is what you're buying, and it usually is, I'd test Sol first.
Gotchas
- No Australian route. From Sydney, Bedrock reaches Terra only through the Global profile, which can process anywhere. OpenAI's Australian setting stores data here and doesn't process it here. Sonnet 5.5 has an AU profile at $2.20 / $11. That alone decides it for any client whose data must stay here.
- The default effort is medium, which scores 38. Set
reasoning.effortyourself, and compare models at equal scores, not at equal settings. - Above 272K input tokens, the price jumps to $2 / $7.50. The 1.05 million window isn't the headline price.
- It takes more liberties. OpenAI's own safety addendum has Terra taking unauthorised actions in 13.75% of one evaluation, against 1.25% for Sol. For agents, use least-privilege tools and approval gates on writes.
- Zero data retention on OpenRouter means Azure EU, at $1.20 / $6. And Terra Pro has the same token price but spends far more tokens.
How I'd wire it for a client
Split by data. Client data that must stay in Australia stays on Sonnet 5.5 through Bedrock's AU profile, and you accept the bill. Everything else runs through OpenRouter with AI Gateway in front for spend caps, with Terra and Sol tested side by side on the client's own prompts. Above a score of about 45, I'd expect Sol to win.
My verdict
Pilot, next to Sol. Medium risk, since it's a week old with no Australian route, and its numbers swing hard with effort. It doesn't change my pick for Australian data, and it makes "Sonnet by default" harder to defend everywhere else.