GPT-6.1 Terra vs Sol: Which OpenAI Model Should You Use in 2026?

What Is GPT-6.1 Terra?

OpenAI released GPT-6.1 Terra on October 26–27, 2026. It is the mid-tier model in the GPT-6.1 family, sitting between GPT-6 Luna (lightweight, cheapest) and GPT-6.1 Sol (deep agentic coding). Terra's positioning is clear from its pricing: $1/$5 per MTok (input/output) versus Sol's $2/$10 — half the cost, with a cached-input rate of just $0.05/MTok.

The headline number is speed. Terra runs roughly 3× faster on average than GPT-6.1 Sol and GPT-6 Astra, making it the default choice for high-throughput workflows where you need near-frontier quality without waiting on Sol's deeper reasoning loops.

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GPT-6.1 Terra vs Sol: Side-by-Side

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When to Use GPT-6.1 Terra

Use Terra when:

You're doing computer use. Terra is the recommended model for UI automation: navigating applications from screenshots, filling forms, extracting data from screen captures, and writing step-by-step instructions from what a screenshot shows. It interprets visual UI elements with high accuracy and responds fast enough for interactive automation loops.

Visual reasoning is the core task. Extracting structured data from charts, comparing screenshots, generating alt text, converting a scanned form to JSON — these are Terra's bread and butter. Sol can do these too, but Terra does them faster and at half the cost.

You need fast, clean professional writing. Emails, help articles, changelogs, product descriptions, meeting notes, API documentation — Terra produces clear, natural prose without the latency of Sol's deeper reasoning pass.

You're running high-volume batch jobs. At $1/$5 MTok and $0.05 cached, Terra is 2× cheaper than Sol for sustained production workloads. For a pipeline processing 10,000 documents a day, the cost difference is material.

You need temperature/top_p control. Setting reasoning_effort: "none" on Terra restores the ability to configure temperature and top_p, which is useful for deterministic extraction (temperature 0) or variable creative generation (temperature 0.7+).

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When to Use GPT-6.1 Sol

Use Sol when:

The task is deep agentic coding. Sol's +6.4-point SWE benchmark improvement over GPT-6 Sol means it's the better tool for multi-file refactors, architect-level code reviews, and security audits that require extended chains of reasoning across a large codebase.

You're orchestrating sub-agents. Sol added beta multi-agent support in the OpenAI Responses API. For agent workflows that need an orchestrator to decompose tasks and coordinate sub-agents, Sol is the right starting point.

You need maximum reasoning depth. For long research synthesis, complex financial modelling, or the most demanding coding problems, Sol's deeper reasoning loops justify the 2× cost premium.

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Copy-Paste Prompts for GPT-6.1 Terra

Here are five ready-to-use prompts optimised for Terra's strengths:

1. Screenshot data extraction: "Extract all structured data from this screenshot as a Markdown table. Flag any cell that is partially visible or unclear with [?]. [attach screenshot]"

2. Computer use — form automation: "Navigate to [URL] and fill the contact form with the following values: Name: [your name], Email: [your email], Message: [your message]. Screenshot the confirmation page when done."

3. Fast professional email: "Draft a 100-word reply to this email in a friendly but professional tone. My key point: [summarise what you want to say in one sentence]. [paste original email]"

4. Alt text for image: "Write alt text (under 125 characters) and a 2-sentence extended description for this image. Context: it appears on our company About page. [attach image]"

5. UI bug report: "Look at this screenshot and write a bug report including: title, severity (Critical/High/Medium/Low), steps to reproduce, actual vs expected behaviour, and a suggested fix. [attach screenshot]"

For the full set of 20 structured prompts across all Terra use cases — computer use, visual reasoning, writing, and coding — see the GPT-6.1 Terra Prompt Generator.

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Related AI Model Guides

GPT-6.1 Sol Prompt Generator — 20 prompts for agentic coding and multi-agent orchestration

GPT-6 Astra Prompt Generator — Frontier tasks, max reasoning, computer use

GPT-6 Pro Prompt Generator — Parallel agents for multi-track research

Claude Sonnet 5.5 Prompt Generator — Anthropic's fast agentic alternative