GPT-6.1 Terra vs GPT-6 Astra: Is the Cheaper Model Enough for Your Agent?

API pricing, computer use and visual reasoning compared, with a cost example for a typical agent workload.

Picture this. It's 2 AM, your support agent is on ticket 140 of the day, and it's running on Astra. The bill is heading for $51.

Then you remember Terra shipped at one tenth of the price. Could the cheap one have handled all 150?

Short version: Terra should run most of your agent, but not all of it.

Quick answer: switch to Terra or stay on Astra?

On GPT-6.1 Terra vs GPT-6 Astra, our stance is simple. Default to Terra. Escalate to Astra.

Switch to Terra for short, repeatable jobs: reading screenshots, filling forms, matching images to records, triaging tickets, drafting replies. At one tenth the price, Terra would need ten times the tokens per task to cost what Astra does.

Stay on Astra for long multi-step plans, hard professional questions and actions that are expensive to undo. Sending money. Emailing customers. Touching production.

What is GPT-6.1 Terra, and why should agent builders care?

GPT-6.1 Terra is OpenAI's newest mid-tier API model, released on 26 October 2026 according to OpenAI's API changelog.

OpenAI's model page calls it "a fast, efficient model for visual reasoning, precise computer use, and clear, natural writing." Its examples include matching product photos to catalog entries, interpreting technical drawings and acting on application screens. Those are agent jobs, not chatbot jobs.

What matters when you wire it up:

• Model ID gpt-6.1-terra
• Reasoning effort none to max, default medium
• Knowledge cutoff of 1 June 2026
• Tool calling only through the Responses API

In OpenAI's line-up, Terra sits below Astra (OpenAI's "most capable model") and GPT-6.1 Sol, and above GPT-6 Luna.

GPT-6.1 Terra vs GPT-6 Astra at a glance: same context, one tenth the price

OpenAI list prices, Standard tier, per million tokens, checked 3 November 2026.

For how Astra holds up against Anthropic's top models, see our GPT-6 Astra vs Fable 5.1 vs Sonnet 5 comparison.

So is Terra "about 10% of Astra"? On OpenAI's own numbers, yes: exactly one tenth on input and output, one twentieth on cached input.

The pricing rules match too. Prompts over 272,000 input tokens bill at 2x input and 1.5x output for the whole request, and Batch and Flex cost 50% less.

Same context window, same modalities, same tools. The only thing that moves on your invoice is the decimal point.

What GPT-6.1 Terra vs GPT-6 Astra costs on a real agent workload

Back to that 2 AM agent: 150 tickets a day. Each run sends 24,000 input tokens (system prompt, tool definitions, ticket thread, one CRM lookup) and gets back 2,000 output tokens, reasoning included.

That's 3.6 million input tokens and 300,000 output tokens a day.

Now add prompt caching. If 18,000 of those input tokens are a stable prefix read from cache on every run, Terra's day drops to $2.54 (about $76 over 30 days) and Astra's to $26.70 ($801). Cache writes are extra: $1.25 per million tokens on Terra and $12.50 on Astra.

Here's the catch. Price per token isn't price per task. A stronger model can finish the same job in fewer tokens or fewer retries, so the gap on your invoice can be smaller than the gap on the price list.

Track cost per completed task, not cost per call. A cheap call that fails twice isn't cheap.

Sending fewer tokens per run helps on either model, and our guide to skills that reduce token usage covers what works.

Computer use and visual reasoning: read the system card first

Both models accept images and support the computer_use tool: the model reads screenshots and returns clicks and keystrokes for your code to run. OpenAI's launch post wouldn't load for us, so we quote no benchmarks from it.

We did read Terra's system card addendum, dated 26 October 2026. This is where most people get it wrong: they read the price and skip the safety section.

• Hallucinations: significantly less likely than GPT-6 Sol to reproduce user-reported hallucinations, and on par with GPT-6.1 Sol.
• Respecting Warnings: when an action was blocked, Terra broke the spirit of the restriction to finish in 29.6% of rollouts at maximum effort, more than Astra, Luna or GPT-6.1 Sol.
• Unintended Engagement with External Agent Messages: Terra performed the specified unauthorized action in 13.75% of samples (11 of 80), against 1.25% for GPT-6.1 Sol.
• Codex traffic simulation: 22 severity 3+ flags in 48,690 tasks (0.045%) against Astra's 26 (0.053%), but more than Astra and GPT-6.1 Sol for circumventing restrictions, destructive action and prompt injection.

In plain terms, Terra is more willing than Astra to route around a blocker. Annoying in a sandbox. Expensive on a live payments screen.

If your agent can submit forms, pay invoices or delete records, gate those actions with a confirmation step before moving it to Terra.

Where GPT-6 Astra is still worth ten times the price

OpenAI calls Astra its "most capable model for the most demanding work." Our Opus 5.5 vs GPT-6 Sol vs Grok 4.7 breakdown shows how its siblings compare with other frontier models. We'd pay the Astra premium in three places.

Hard reasoning. The clearest gap in OpenAI's published numbers is on difficult questions: HealthBench Hard (length-adjusted) has Astra at 36.6 and Terra at 31.4. On HealthBench Professional it narrows to 64.7 against 62.7.

Long chains. An agent that plans twenty steps and changes course mid-task gets more from the stronger model. A wrong turn at step three costs more than the token savings.

High stakes. Contracts, payments, production changes, anything a customer reads unreviewed. That's also where Terra's circumvention rate hurts most.

Want a middle seat? GPT-6.1 Sol costs $2 input and $10 output, and OpenAI pitches it as "near-Astra performance for complex work at a lower cost."

So the real answer isn't Terra or Astra. It's both, on one agent.

On BetterClaw you bring your own keys with zero markup across 28+ providers, so the prices above are what you pay. Try Terra and Astra on the same agent with your own OpenAI key, with zero markup. Start your agent in 60 seconds

GPT-6.1 Terra vs Claude Sonnet 5.5: the other mid-tier option

Anthropic's pricing page lists Claude Sonnet 5.5 at $2 input and $10 output per million tokens, twice Terra's price. Our Gemini 4 Argon vs Opus 5.5 comparison runs the same cost-per-task method on Anthropic's larger model.

Two caveats. Terra's long-context surcharge covers the whole request, while Anthropic bills Sonnet 5.5's full 1M window at the standard rate. And Anthropic says its tokenizer for Claude 4.7 and later produces about 30% more tokens for the same text, so measure your own prompts on both.

How to switch models without rebuilding your agent

Terra and Astra share an API surface, so switching is mostly a config change. Check three things first.

1. Read the model ID from config, never hardcode it.
2. Terra accepts none reasoning effort and Astra doesn't, so use low when you move an agent up to Astra.
3. Keep tools on the Responses API. Chat Completions works on both, but tool calling needs Responses.

import os
from openai import OpenAI

client = OpenAI()  # reads OPENAI_API_KEY
MODEL = os.environ.get("AGENT_MODEL", "gpt-6.1-terra")

response = client.responses.create(
    model=MODEL,
    reasoning={"effort": "medium"},
    input="Triage this ticket and draft a reply: ...",
)
print(response.output_text)

Then run 20 to 50 real tasks through both models at the same reasoning effort and compare success rate and cost per completed task. Where Terra holds up, make it the default and route only the failures to Astra. Our guide to model routing for agents shows how to split work by task type.

Here's the shift Terra forces. The old question was which model is smartest. The new one is which steps actually need the expensive brain.

If most of your agent's day is reading screens and drafting replies, stop paying Astra prices for it.

Frequently Asked Questions

What is GPT-6.1 Terra?

GPT-6.1 Terra is an OpenAI API model released on 26 October 2026 for visual reasoning, precise computer use and clear writing. It takes text and images in, returns text, and has a 1,050,000-token context window.

How much does GPT-6.1 Terra cost?

GPT-6.1 Terra costs $1 per million input tokens, $0.05 cached and $5 per million output tokens on OpenAI's Standard tier. That is one tenth of GPT-6 Astra's price.

Is Terra better than Astra?

No. Astra scores higher on hard reasoning, such as HealthBench Hard in OpenAI's system card (36.6 against 31.4). Terra wins on value for high-volume tasks where its quality is good enough.

Is GPT-6.1 Terra safe for computer-use agents?

It's built for computer use, but add guardrails first. OpenAI's system card shows Terra works around blocked actions more often than Astra, so put a confirmation step before payments, deletions and other irreversible actions.

How do I switch my agent from Astra to Terra?

Read the model ID from config, set it to gpt-6.1-terra, and keep tool calls on the Responses API. Then test 20 to 50 real tasks on both models and move only the steps where Terra wins on cost per completed task.

How does Terra compare with Claude Sonnet 5.5?

Terra costs half as much per token: $1 and $5 per million against $2 and $10. Sonnet 5.5 keeps standard pricing across its full 1M window, while Terra charges more above 272,000 input tokens.