GPT-6 Astra

OpenAI’s docs name GPT-6 Astra as the place to start for complex reasoning and coding. It accepts text and images, returns text, and supports five reasoning-effort levels, from low up to max.

When to choose it

• Hard, end-to-end tasks: research write-ups, multi-file code changes, analysis that has to hold together over many steps.
• You want OpenAI’s hosted tools in one call: web search, file search, code interpreter, a hosted shell, computer use, skills and remote MCP servers.
• You already build on the OpenAI API and want its strongest general model.

For cost-sensitive work, OpenAI points to GPT-5.6 Terra (a fifth of the input price) or GPT-5.6 Luna for high-volume jobs.

Specs (from OpenAI, 2026-09-25)

API ID	gpt-6-astra
Context window	1,050,000 tokens (max 922,000 input)
Max output	128,000 tokens
Price	$10 per million input tokens, $50 per million output tokens
Cached input	$1 per million tokens; cache writes $12.50
Knowledge cutoff	April 30, 2026

Before you choose

Long prompts cost more: once a request goes over 272K input tokens, the whole request is billed at 2x input and 1.5x output. Batch and Flex are half price. Fast mode costs double. Fine-tuning isn’t available for this model.