Gemini 3.1 Flash Image Preview (Nano Banana 2)

gemini-3.1-flash-image-preview is the Gemini 3.1 Flash image model for generation and editing. nano-banana-2 is an alias for the same model id contract. Use the size field to request compact, standard, 2K, or 4K outputs instead of switching model ids.

API surface

Operation	Endpoint	Mode
Image generation	POST /v1/images/generations	Sync
Image generation task	POST /v1/async/images/generations	Async
Image editing	POST /v1/images/edits	Sync
Image editing task	POST /v1/async/images/edits	Async

Pricing

Credits

Model id	Resolution	Credits / image
gemini-3.1-flash-image-preview-512	512px	4
gemini-3.1-flash-image-preview	1K (1024px)	4
gemini-3.1-flash-image-preview-2k	2K (2048px)	6
gemini-3.1-flash-image-preview-4k	4K (4096px)	8

Request fields

This model uses the same OpenAI-compatible image fields as the rest of Pixapi.

Field	Type	Required	Description
model	string	Yes	Use gemini-3.1-flash-image-preview or the alias nano-banana-2.
prompt	string	Yes	Describe the desired image or edit.
image	file or file[]	Required for edits	Send via /v1/images/edits when editing input images.
n	number	No	Number of images to return.
size	string	No	Output size such as 512x512, 1536x1024, 2K, 4K, or another model-supported size.
response_format	string	No	url or b64_json when supported.

Example

{
  "model": "gemini-3.1-flash-image-preview",
  "prompt": "A clean product hero image for an API dashboard",
  "n": 1,
  "size": "1536x1024"
}

For the shared response shape and edit upload example, see the API Reference.