GPT-6 Luna vs. GPT-5.6 Luna

GPT-6 Luna is OpenAI’s efficiency-focused GPT-6 model for developers and users who need capable reasoning, coding, computer use, and agentic workflows at very low inference cost. It is positioned below GPT-6 Sol and GPT-6 Astra in the model family while bringing many of the GPT-6 generation’s improvements to applications that prioritize scale and affordability. The model supports configurable reasoning effort so developers can allocate additional computation to complex tasks while keeping simpler interactions fast and economical. GPT-6 Luna can power business automation across applications used for sales, marketing, finance, operations, customer support, and human resources. Its coding capabilities support work on real software repositories, including multi-step engineering tasks that require analysis, modification, testing, and iteration. Luna can also operate in computer-use environments, allowing agents to navigate graphical interfaces and complete extended workflows across software applications. OpenAI reports that GPT-6 Luna substantially improves factual reliability compared with GPT-5.6 Luna and can approach the capabilities of more expensive models on some tasks when used at higher reasoning levels. The model also benefits from GPT-6’s improved collaboration style, with clearer technical communication, less unnecessary jargon, and fewer low-value details. Enhanced prompt caching allows applications to reuse previously processed context at a discount while preserving cache reuse when reasoning effort or available tools change. These efficiency improvements make Luna suitable for high-volume agents, coding assistants, automated workflows, customer-facing applications, and other systems where per-request cost is important. GPT-6 Luna is available through the OpenAI API as gpt-6-luna, as well as through ChatGPT Work, Codex, and supported ChatGPT desktop experiences.

GPT-5.6 Luna is the lowest-cost model in OpenAI’s GPT-5.6 family, built for fast and affordable AI assistance across everyday and technical workflows. The GPT-5.6 lineup includes Sol as the flagship model, Terra as the balanced model for everyday work, and Luna as the efficient model for users who need strong capability at lower cost. Luna is intended for developers, businesses, and teams that need scalable AI for coding help, workflow automation, research support, analysis, customer-facing applications, and high-volume API usage. In the pasted preview text, Luna is presented as part of the same GPT-5.6 release process and benchmark set as Sol and Terra. It appears in evaluations for command-line coding workflows, long-horizon biology tasks, ExploitBench, and ExploitGym, indicating that it is designed to handle more than simple chat use cases. The model is priced at a lower per-token rate than Sol and Terra, making it more suitable for applications where cost efficiency is a major priority. GPT-5.6 Luna also supports the new GPT-5.6 prompt caching approach, including explicit cache breakpoints, a 30-minute minimum cache life, cache writes billed above the uncached input rate, and discounted cached-input reads. Like the rest of the GPT-5.6 family, Luna is developed with layered safeguards matched to model capability. These safeguards include trained refusals for prohibited cyber assistance, real-time misuse classifiers, paused generation for higher-risk cases, account-level review, monitoring, enforcement, automated red-teaming, and third-party human expert red-teaming. Luna is expected to support legitimate defensive and technical workflows such as code review, debugging, patch development, security education, and defensive testing while making prohibited misuse more difficult and detectable. GPT-5.6 Luna helps organizations deploy GPT-5.6-class AI where speed, affordability, scalability, and safe production use are the most important requirements.