GPT-6 Luna

GPT-6 Luna is OpenAI's GPT-6 model for focused, high-volume tasks. It supports text and image input with text output, a 1,050,000-token context window (maximum input 922,000 tokens), and 128,000 output tokens. Reasoning effort supports none, low, medium (API default), high, xhigh, and max. Responses API supports reasoning with function calling and built-in tools; Chat Completions function calling requires reasoning effort none. Standard per-million-token pricing is $0.1 input, $0.01 cached input, $0.125 cache writes, and $0.5 output. Prompts above 272K input tokens cost 2x input/cache and 1.5x output across the full request. Batch and Flex cost 50% of Standard; Fast costs 2x applicable rates. Regional processing adds 10% where available. Launch benchmarks are OpenAI-reported; effort, cost per task, and evaluation variants are recorded with each score.