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GPT-5.6 Luna

OpenAI · GPT Luna line · lightweight

Released July 9, 2026Replaced by GPT-6 Luna

GPT-5.6 Luna was released by OpenAI on July 9, 2026, as a lightweight model in the GPT Luna line.

  • Release 4 of 5 in the GPT Luna line.
  • Came 114 days after GPT-5.4 nano, released Mar 17, 2026.
  • Replaced by GPT-6 Luna on September 22, 2026, 75 days later.
  • These days the line ships a new model about every 115 days.

What changed

The lightest tier of the GPT-5.6 trio, positioned by OpenAI as the fast, affordable model: $0.20 per million input tokens and $1.20 per million output tokens after the 30 July price cut.

Sources: OpenAI · OpenAI

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Where the GPT Luna line stands

GPT-6 Luna is the current model in this line. The card shows how long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.

GPT Luna

OpenAI · lightweight line

Latest: GPT-6 Luna · Sep 22, 2026

Just released32 days since the last release · usual gap 115 days

Half the input price and 58% less on output than GPT-5.6 Luna, with a 1-point higher all-round score.

What changed in GPT-6 Luna →
Days since last release
32
days
Usual gap
115
days
Recent gaps
GPT-6 Luna · Sep 2026
75
GPT-5.6 Luna · Jul 2026
114
GPT-5.4 nano · Mar 2026
222
GPT-5 nano · Aug 2025
115

Every GPT Luna release

Newest first. See the full line with every card →

  1. Sep 22, 2026GPT-6 Luna
  2. Jul 9, 2026GPT-5.6 Luna · this page
  3. Mar 17, 2026GPT-5.4 nano
  4. Aug 7, 2025GPT-5 nano
  5. Apr 14, 2025GPT-4.1 nano