GPT-5.5 vs GPT-6 Astra

OpenAI's GPT-5.5 against OpenAI's GPT-6 Astra — price, context and what each is best at. Both are available through one OpenAI-compatible API.

AnyModel — you pay	GPT-5.5	GPT-6 Astra
Vendor	OpenAI	OpenAI
Input / 1M	$0.15	$0.3
Output / 1M	$0.15	$0.3
Context	400K	1M
Best for	Complex coding	Codex CLI

GPT-5.5

OpenAI's flagship for coding, agents and research-grade reasoning.

GPT-5.5 is OpenAI's top general-purpose model and the engine behind modern Codex: state-of-the-art coding, computer use and multi-step reasoning with a 400K-token window on this route. The default pick when you want one model that handles everything.

More about GPT-5.5 →

GPT-6 Astra

OpenAI's most capable model for complex, demanding work.

GPT-6 Astra is OpenAI's flagship reasoning and agentic-coding model: the top of the Codex line for multi-step engineering, deep debugging and long autonomous sessions, with reasoning effort up to max. Pick it when Sol is not enough. Served by ChatGPT Pro accounts, so capacity is limited.

More about GPT-6 Astra →

Quick take: pick GPT-5.5 when cost matters most; pick GPT-6 Astra when you need the largest context. With AnyModel you don't have to choose up front — switch the model id any time.

FAQ

Which is cheaper, GPT-5.5 or GPT-6 Astra?

GPT-5.5 is cheaper on output tokens ($0.15 vs $0.3 per 1M).

Which has a larger context window, GPT-5.5 or GPT-6 Astra?

GPT-6 Astra has the larger context window (1M).