GPT-5.6 Luna

Available

A lower-priced GPT-5.6 API option with configurable reasoning and image input.

Access details: OpenAI · Responses API

Undated identifier · Undated API identifier. This pilot does not claim an immutable weights snapshot behind it.

gpt-5.6-luna

Source check: Sep 13, 2026

Sources & notes →

Capabilities & limits

Context window: 1.05M
Maximum output: 128K
Image input: Supported
Tool calling: Supported
Structured output: Supported

Documented interfaces and limits. These are not measures of model quality.

Pricing

USD / 1M tokens

Input: $0.20
Output: $1.20

Standard text rates after the July 30 price change. Above 272K input tokens, different rates apply. Cache, batch, tools, and regional premiums are excluded.

Full rate card 6 rates

Amounts in USD. Check the unit and conditions on each rate.

Standard input

$0.20 per 1M tokens

standard processing
excludes cached input
excludes Batch API
excludes tool fees

Standard output

$1.20 per 1M tokens

standard processing
excludes Batch API
excludes tool fees

Cached input

$0.02 per 1M tokens

prompt caching

Cache writes

$0.25 per 1M tokens

1.25x uncached input rate

Long-context input

$0.40 per 1M tokens

request has more than 272K input tokens
rate applies to the full request

Long-context output

$1.80 per 1M tokens

request has more than 272K input tokens
rate applies to the full request

Prompts over 272K input tokens: 2x input and 1.5x output

Price history

Jul 9, 2026

Input Not verified per million tokens

Earlier amount is not verified; the current rate cannot fill this historical gap.

Jul 30, 2026

Input $0.20 per million tokens

Jul 9, 2026

Output Not verified per million tokens

Earlier amount is not verified; the current rate cannot fill this historical gap.

Jul 30, 2026

Output $1.20 per million tokens

Technical details

Training / knowledge cutoff: Feb 16, 2026
Input modalities: text, image
Output modalities: text

3 details not verified

Parameters
Active parameters
Architecture

Audio and video are not supported. The model page documents reasoning support.

From OpenAI

Official announcement link: not verified yet.

How they describe it

GPT-5.6 model optimized for cost-sensitive workloads

What they say is different

Provider quote not captured yet.

Verbatim provider claims · not an independent assessment

Release & lifecycle

Availability applies to this exact identifier on OpenAI · Responses API.

First API availability: Jul 9, 2026
available: Observed Sep 13, 2026

Read the Atlas release story ↗