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

OpenAI's GPT-5.6 family introduces three model tiers — Sol, Terra, and Luna — so you pick the right tool for each task instead of one-size-fits-all.

🟢 Why It Matters

🟢 Smart tiering — flagship for deep work, economy for high volume 🟢 Massive savings — Luna delivers ~90% of competing performance at ~⅓ the cost 🟢 New capabilities — max reasoning for deep thinking, ultra mode running 4 parallel agents

🟢 The Three Models

🌞 Sol ($5 in / $30 out) — The flagship. Scores 80 on the Coding Agent Index, 2.8 points above Claude Fable 5, using fewer than half the tokens at ~⅓ less cost. Breakthrough cybersecurity: ExploitBench 73.5% vs GPT-5.5's 47.9%. Best for complex coding, scientific research, cybersecurity, and multi-step agentic apps.

🌍 Terra ($2.50 in / $15 out) — The balanced workhorse. Outperforms Fable 5 at ~4x lower cost and nearly matches GPT-5.5 at half the price. Best for everyday professional work, reports, analysis, and software planning.

🌙 Luna ($1 in / $6 out) — The cost king. Outperforms Anthropic's Opus 4.8 despite being dramatically cheaper. Best for high-volume text processing, summarization, classification, data extraction, and quick drafts.

All models support Prompt Caching — 90% discount on cached input reads.

🟢 Key Benchmarks

🟢 Coding Agent Index 80 — Sol leads in agentic coding 🟢 BrowseComp 92.2% — 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%

🟢 Routing Strategy

🟢 Complex coding (DB migration + new API) → Sol 🟢 Weekly data analysis → Terra 🟢 Classify 10,000 customer reviews → Luna 🟢 Unclear → start Terra, escalate to Sol if needed

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

🟢 What's New

🟢 Ultra mode — launches 4 parallel agents on the same task for better, faster results 🟢 Programmatic tool calling — model filters intermediate data internally, fewer round-trips 🟢 Stronger computer use — model sees and refines its own visual output (websites, presentations, mini-games)

Free and Go ChatGPT users get Terra at no extra cost. Plus, Pro, Business, and Enterprise tiers get Sol.

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