GPT-5.6 Terra — Pantheon
  
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    # GPT-5.6 Terra

    
OpenAI · released 9 Jul 2026 · current mid tier
    
The middle tier of the GPT-5.6 generation, released 9 July 2026: pitched at launch as the balanced everyday model, with GPT-5.5-competitive performance at half the price ($2.50/$15 per million tokens). In OpenAI’s new naming system the number marks the generation and Sol / Terra / Luna are durable tiers that can advance on their own cadence.
    
Fresh page (19 Jul 2026) — visibly incomplete by design. The generation-level launch record (the government-preview arc, the early safety writeups, ChatGPT Work) is fullest on [Sol’s page](../gpt-5-6-sol/) — Sol was the only tier public during the preview window; this page holds what is Terra-specific and will grow as a distinct record accumulates — if one does. Corpus pass pending.

    
## Sources

    
### Official

    

      
- 2026-07-09 [GPT-5.6 launch post](https://openai.com/index/gpt-5-6/) — Terra introduced with the family.
      
- 2026-07 [Help center](https://help.openai.com/en/articles/20001325-a-preview-of-gpt-56-sol-terra-and-luna) — shared specs: 1M context, 128K max output, cutoff 16 Feb 2026.
    
    
### Writing & commentary

    

      
- 2026-07-09 [Simon Willison](https://simonwillison.net/2026/Jul/9/gpt-5-6/) — day-of family read.
      
- 2026-07 Zvi Mowshowitz, [Better Call Sol The Workhorse](../mirror/posts/zvi-better-call-sol.md) (mirrored) — covers the cheaper tiers alongside Sol.
      
- 2026-06-28 Zvi Mowshowitz, [GPT-5.6: The System Card](../mirror/posts/zvi-gpt-56-system-card.md) (mirrored) — the generation’s system-card read; preview-era (predates Terra’s public release; only Sol was live).
    
    
### Tweets

    
tk — corpus pass pending; the local dbs end before launch.

    
## Official record

    

      
- Mid tier of the GPT-5.6 generation: “balanced model for everyday work,” GPT-5.5-competitive performance at 2× lower cost, as published.
      
- Pricing $2.50 / $15 per Mtok; shared generation specs: 1M context, 128K max output, cutoff 2026-02-16.
      
- Generation naming: the number marks the generation; Sol / Terra / Luna are durable capability tiers advancing on their own cadence, per OpenAI.
      
- tk — checkpoint strings, published benchmarks, which ChatGPT surfaces default to Terra.
    

    
## History

    

      
- 2026-07-09 Released with the generation (public launch followed a government-approved limited preview of Sol from 26 Jun; shipped alongside the ChatGPT Work product). Siblings: [Sol](../gpt-5-6-sol/) (flagship) and [Luna](../gpt-5-6-luna/) (fast tier).
      
- tk — whether Terra develops a distinct record from its siblings; reception specific to Terra.
    

    
## Impressions

    
tk — too fresh; no attributed Terra-specific reads yet.

    
    
    
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