GPT-5.6 Sol, Terra & Luna: Pricing, Comparison, and Complete Usage Guide

"OpenAI released a new model" — this phrase repeats almost monthly. But GPT-5.6 is different. For the first time, OpenAI is launching three model tiers instead of one: Sol for frontier intelligence, Terra for everyday value, and Luna for maximum efficiency.

This guide breaks down the differences, pricing, benchmarks, and how to practically use each one — whether you're a developer, business owner, or researcher.

Why GPT-5.6 Matters (Three Key Points)

• Smart tiering: Instead of one model for everyone, you pick the right tool — flagship for deep work, economy for high volume
• Massive savings: Luna delivers ~90% of competing models' performance at roughly ⅓ the cost
• New capabilities: max reasoning for deep thinking, ultra mode running 4 agents in parallel

The Three Models — Which One Fits You?

🌞 Sol — The Flagship

The most capable model OpenAI has built.

• Model ID: gpt-5.6-sol
• Pricing: $5 per 1M input tokens / $30 per 1M output tokens
• Reasoning effort: medium, high, xhigh, max, ultra

For developers: Sol scores 80 on the Coding Agent Index — 2.8 points above Claude Fable 5, while using fewer than half the output tokens, taking less than half the time, and costing about one-third less.

For cybersecurity: Breakthrough performance — 73.5% on ExploitBench vs GPT-5.5's 47.9%, and 96.7% on Capture-the-Flag challenges.

For science & research: GeneBench Pro 28.7%, LifeSciBench 59.9% — clear advances in scientific reasoning.

Best for:

• Complex coding tasks needing deep reasoning
• Scientific research and analysis
• Cybersecurity (vulnerability research, code review, threat modeling)
• Multi-step agentic applications

🌍 Terra — The Balanced Workhorse

Strong performance at a reasonable cost.

• Model ID: gpt-5.6-terra
• Pricing: $2.50 input / $15 output
• Reasoning effort: Same options as Sol

Terra outperforms Fable 5 on the Coding Agent Index at roughly 4x lower estimated cost. It nearly matches GPT-5.5's peak and Claude Mythos 5 performance at half the price.

Best for:

• Everyday professional work — reports, analysis, coding
• Software planning and requirements analysis
• Tasks needing a balance of quality and cost

🌙 Luna — The Cost King

Fastest and most affordable.

• Model ID: gpt-5.6-luna
• Pricing: $1 input / $6 output
• Reasoning effort: Basic options

Luna outperforms Anthropic's Opus 4.8 despite being dramatically cheaper. Ideal for high-volume tasks where cost-efficiency matters more than peak performance.

Best for:

• High-volume text processing
• Summarization, classification, data extraction
• Quick drafts before refinement
• Repetitive, well-defined tasks

Pricing Comparison

• Sol: $5 in / $30 out — the powerhouse, use for critical tasks
• Terra: $2.50 in / $15 out — the balanced default
• Luna: $1 in / $6 out — the budget champion for volume

All models support Prompt Caching — 90% discount on cached input reads. If your app has repeated query patterns, costs drop dramatically.

Key Benchmarks

• Coding Agent Index 80 — Sol leads in agentic coding
• BrowseComp 92.2% — Sol sets new SOTA in web browsing comprehension
• OSWorld 2.0 62.6% — Beats Opus 4.8 with 85% fewer output tokens
• ExploitBench 73.5% — Massive leap from GPT-5.5's 47.9%

Practical Routing Strategy

• Complex coding task (DB migration + new API): Use Sol
• Weekly data analysis report: Use Terra
• Classify 10,000 customer reviews: Use Luna
• Unclear task or Luna didn't cut it: Start with Terra, escalate to Sol if needed

This routing strategy saves 50-70% on costs compared to using Sol for everything.

What's New

Ultra Mode (Multi-Agent Reasoning)

ultra launches 4 parallel agents working on the same task. It distributes complex work across multiple "minds" — the result is better and faster. Perfect for large codebases or research needing parallel exploration.

Programmatic Tool Calling

The model filters intermediate data internally instead of sending everything back to you. Fewer round-trips, lower cost — essential for apps using multiple external tools.

Stronger Computer Use

The model can now see and refine its own visual output — website designs, presentations, mini-games. It produces tasteful, functional interfaces from high-level direction.

Frequently Asked Questions

What is the price of GPT-5.6 Sol per million tokens?

GPT-5.6 Sol costs $5 per 1M input tokens and $30 per 1M output tokens. This is the flagship model designed for complex tasks requiring deep reasoning.

Is GPT-5.6 Terra free in ChatGPT?

Yes, Free and Go ChatGPT users get GPT-5.6 Terra at no additional cost. Higher tiers (Plus, Pro, Business, Enterprise) get access to Sol.

What's the main difference between Sol, Terra, and Luna?

• Sol: Flagship — highest intelligence, for critical tasks
• Terra: Balanced — strong performance at reasonable cost, great for everyday work
• Luna: Cost-efficient — fastest and cheapest, perfect for high-volume tasks

Which is better for coding — GPT-5.6 Sol or Claude Fable 5?

GPT-5.6 Sol scores 80 on the Coding Agent Index, ahead of Fable 5's 77.2, while using fewer than half the output tokens, taking less than half the time, and costing about one-third less.

What is the GPT-5.6 Luna model ID and price?

Model ID: gpt-5.6-luna — Price: $1 input / $6 output per million tokens. Ideal for high-volume text processing at minimal cost.

What is ultra mode in GPT-5.6?

ultra mode launches 4 parallel agents working on the same task. It distributes complex work across multiple "minds" working together — delivering better results faster than any other setting.

How do I choose the right model for my project?

Start with Luna for simple, high-volume tasks. Use Terra for everyday professional work. Reserve Sol for complex coding and scientific tasks. This strategy saves 50-70% on costs.

What is the GPT-5.6 Luna API price?

GPT-5.6 Luna is the most affordable — $1 per 1M input tokens and $6 per 1M output tokens. It's cheaper than DeepSeek V3 on output tokens with higher quality.

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