GPT Image 2.5 API Reference | Nano Banana Pro API

GPT Image 2.5

GPT Image 2.5 for sharper detail, cleaner typography and up to 4K output, in two looks

Features

Text-to-image and image-to-image (up to 16 reference images)
1K, 2K and 4K output with 13 aspect ratios, or auto
Two looks: flare (default) and sunburst
Standard mode for every account; economy mode at a lower price once the account has a purchase

Pricing

Mode	1K	2K	4K
standard, account with a purchase	8	14	20
standard, account without a purchase	16	28	40
economy (needs a purchase)	5	8	12

Credits per image. Without a purchase, economy returns 403 purchase_required before anything is charged.

Endpoint

POST/api/v1/images/generate

Parameters

Parameter	Type	Required	Description
model	string	Required	Must be "gpt-image-2.5"
type	string	Optional	"text-to-image" or "image-to-image" (default: text-to-image)
prompt	string	Required	Text description (3–20000 chars)
image_urls	string[]	Optional	Required for image-to-image. 1–16 public https image URLs
image_size	string	Optional	Aspect ratio: "auto" (default), "1:1", "3:2", "2:3", "4:3", "3:4", "16:9", "9:16", "21:9", "27:16", "16:27", "9:8" or "8:9"
resolution	string	Optional	"1K" (default), "2K" or "4K"
variant	string	Optional	Look of the image: "flare" (default) or "sunburst"
generation_mode	string	Optional	"standard" (default) or "economy". Economy needs an account with a purchase
num_images	number	Optional	Must be 1

Request Example (Text-to-Image)

JSON

{
  "model": "gpt-image-2.5",
  "resolution": "2K",
  "image_size": "3:2",
  "prompt": "A product shot of a glass perfume bottle on wet black stone, soft rim light"
}

Request Example (Image-to-Image)

JSON

{
  "model": "gpt-image-2.5",
  "type": "image-to-image",
  "resolution": "2K",
  "prompt": "Replace the background with a sunlit marble counter, keep the bottle unchanged",
  "image_urls": [
    "https://example.com/your-product.png"
  ]
}

Response Example

JSON

{
  "success": true,
  "data": {
    "task_id": "g25-3f9c1e…",
    "credits_used": 14,
    "remaining_credits": 486,
    "model": "gpt-image-2.5",
    "resolution": "2K"
  }
}

Code Examples (Text-to-Image)

curl -X POST https://preview.bananapro.site/api/v1/images/generate \
  -H "Authorization: Bearer sk-your-api-key" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: a-unique-id-per-request" \
  -d '{
    "model": "gpt-image-2.5",
    "resolution": "2K",
    "image_size": "3:2",
    "prompt": "A product shot of a glass perfume bottle on wet black stone, soft rim light"
  }'

Code Examples (Image-to-Image)

curl -X POST https://preview.bananapro.site/api/v1/images/generate \
  -H "Authorization: Bearer sk-your-api-key" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: a-unique-id-per-request" \
  -d '{
    "model": "gpt-image-2.5",
    "type": "image-to-image",
    "resolution": "2K",
    "prompt": "Replace the background with a sunlit marble counter, keep the bottle unchanged",
    "image_urls": [
      "https://example.com/your-product.png"
    ]
  }'

Mode

standard, account with a purchase

standard, account without a purchase

economy (needs a purchase)

Parameter

Type

Required

Description

model

string

Required

Must be "gpt-image-2.5"

type

string

Optional

"text-to-image" or "image-to-image" (default: text-to-image)

prompt

string

Required

Text description (3–20000 chars)

image_urls

string[]

Optional

Required for image-to-image. 1–16 public https image URLs

image_size

string

Optional

Aspect ratio: "auto" (default), "1:1", "3:2", "2:3", "4:3", "3:4", "16:9", "9:16", "21:9", "27:16", "16:27", "9:8" or "8:9"

resolution

string

Optional

"1K" (default), "2K" or "4K"

variant

string

Optional

Look of the image: "flare" (default) or "sunburst"

generation_mode

string

Optional

"standard" (default) or "economy". Economy needs an account with a purchase

num_images

number

Optional

Must be 1

{ "model": "gpt-image-2.5", "type": "image-to-image", "resolution": "2K", "prompt": "Replace the background with a sunlit marble counter, keep the bottle unchanged", "image_urls": [ "https://example.com/your-product.png" ] }

curl -X POST https://preview.bananapro.site/api/v1/images/generate \ -H "Authorization: Bearer sk-your-api-key" \ -H "Content-Type: application/json" \ -H "Idempotency-Key: a-unique-id-per-request" \ -d '{ "model": "gpt-image-2.5", "resolution": "2K", "image_size": "3:2", "prompt": "A product shot of a glass perfume bottle on wet black stone, soft rim light" }'

curl -X POST https://preview.bananapro.site/api/v1/images/generate \ -H "Authorization: Bearer sk-your-api-key" \ -H "Content-Type: application/json" \ -H "Idempotency-Key: a-unique-id-per-request" \ -d '{ "model": "gpt-image-2.5", "type": "image-to-image", "resolution": "2K", "prompt": "Replace the background with a sunlit marble counter, keep the bottle unchanged", "image_urls": [ "https://example.com/your-product.png" ] }'