GPT-5.6 Luna changelog

ChatGPT replaces GPT-5.5 Instant with GPT-5.6 Sol and Luna

Free and Go users got a new default model for everyday chats, and Plus and Pro users got an updated GPT-5.6 Sol with an effort slider. These models replaced GPT-5.5 Instant.

Who is affected:

Everyone using ChatGPT.

What to do:

No action needed. Expect different answers than GPT-5.5 Instant.

GPT-5.6 Luna 80% cheaper, Terra 20% cheaper

Starting July 30, GPT-5.6 Luna costs 80% less and GPT-5.6 Terra costs 20% less on the API.

Who is affected:

Apps using GPT-5.6 Luna or Terra.

What to do:

No action needed. Costs drop automatically.

GPT-5.6 Sol, Terra and Luna available in GitHub Copilot

GPT-5.6 Sol is available on Copilot Pro+, Max, Business and Enterprise. Terra and Luna are also available on Pro. All are billed at provider list price, and Business and Enterprise admins must turn on the policy, which is off by default.

Who is affected:

GitHub Copilot users choosing OpenAI models.

What to do:

Copilot Business and Enterprise admins: enable the GPT-5.6 policy if you want these models.

GPT-5.6 family released: Sol, Terra and Luna

OpenAI released three GPT-5.6 models on the Responses, Chat Completions and Batch APIs. The gpt-5.6 alias routes to gpt-5.6-sol, and the release adds max reasoning effort, Pro mode and multi-agent orchestration in beta.

Who is affected:

Developers on GPT-5.5, GPT-5.4 and older models.

What to do:

Evaluate gpt-5.6-terra or gpt-5.6-luna for cost-sensitive workloads.