Quality close to GPT-5.5
OpenAI positions Terra to compete with GPT-5.5 on performance—suited to moving a large share of former single-flagship traffic onto a more balanced choice.
OpenAI · GPT-5.6 Terra · July 2026
GPT-5.6 Terra — high-efficiency primary model near GPT-5.5 quality
- Million-token context
- Extra-long single replies
- Near GPT-5.5 quality
- Balanced throughput and depth
What is GPT-5.6 Terra?
GPT-5.6 Terra is OpenAI’s balanced GPT-5.6 model, released in July 2026. It targets everyday coding, reasoning, and agents: OpenAI positions it to compete with GPT-5.5 performance while sitting between Sol and Luna on cost and throughput. Keep the heaviest, longest jobs on Sol; high-turnover drafts and short-turn automation fit Luna better. On iMini Agent, pick GPT-5.6 Terra to use it.
- Vendor
- OpenAI
- Released
- July 2026
- Context
- 1M tokens
- Max output
- 128K tokens
- Deep reasoning
- Tunable · balanced posture
- Best as
- Everyday primary on the OpenAI stack
What’s new versus GPT-5.5
Family roles, everyday primary cost, and the shared tool surface—what to check before making Terra your day-to-day go-to.
Sits between Sol and Luna
Depth and cost land between Sol and Luna. For new work, ask first whether Sol is worth it—or whether Terra is already steady enough.
Still configured for million-token context
Context and output ceilings match the family’s flagship tier, so long specs, multi-turn history, and tool traces can stay in one conversation.
Access to GPT-5.6 family capabilities
Shares reasoning, tool use, and multi-agent surfaces with the generation—so Agent workflows can switch among Sol / Terra / Luna by task weight.
Official evaluations
Results OpenAI published with GPT-5.6. The shared x-axis is output-token volume. Terra’s story: clearly fewer tokens for scores close to Sol.
Three common workflows
GPT-5.6 Terra is built as an everyday primary, leaving the heaviest minority of jobs for Sol.
Day-to-day coding & code review
For routine feature work, PR review, and test repair. Focus on stable, checkable changes and verification advice—hand truly hard long-horizon refactors to Sol.
High-volume business & document analysis
For support drafts, internal tool docs, contracts, and long-document summaries. Suited to high throughput that still needs reliable reasoning.
Medium-length agent flows
For multi-step tool use that stays within a controlled number of turns. Pin completion criteria so not every request burns flagship depth.
How to choose vs GPT-5.6 Sol and GPT-5.6 Luna
Three tiers in one generation. The differences are depth ceiling, throughput, and failure cost.
| Dimension | GPT-5.6 Terra | GPT-5.6 Sol | GPT-5.6 Luna |
|---|---|---|---|
| Context | 1M tokens | 1M tokens | 1M tokens |
| Reasoning | Balanced depth | Max depth · ultra available | Lighter and faster |
| Coding / agents | Day-to-day coding & mid-weight agents | Heaviest long-horizon coding & security research | Short-turn automation & drafts |
| Long tool runs | More balanced completion and throughput | Flagship depth + ultra | High turnover, shorter threads |
| Speed posture | Everyday primary favors balance | Completion quality and depth first | Responsiveness and cost first |
| Prefer when | New everyday coding and high-volume business work | Highest failure-cost, heaviest jobs | Drafts, classification, and short-turn automation |
Using GPT-5.6 Terra on iMini
Free quota, model naming, key specs, and how it differs from Sol and Luna.
Use GPT-5.6 Terra free on iMini Agent
Million-token context, near-flagship quality, built as an everyday primary.
Open GPT-5.6 TerraNo OpenAI API key required.