Nano Banana Pro API (gemini-3-pro-image-preview)

$0.03 per image at default resolution — one OpenAI-compatible endpoint at https://api.apimart.ai/v1, no monthly plan required. (observed 2026-09-17)

Get an API key · Live pricing · Model page · ⚡ 60-second quickstart

Why teams call Nano Banana Pro (gemini-3-pro-image-preview) through APIMart

• One key, entire catalog. The same https://api.apimart.ai/v1 base URL and Authorization header reach Nano Banana Pro (gemini-3-pro-image-preview) and 300+ other image, video and language models — switch the model field, not your client.
• $1 minimum, pay as you go. No subscription and no prepaid plan to size up front: top up from $1 and spend it on calls. There is no free quota to burn through first, so the price in this table is the price you pay.
• The charge comes back in the response. Every call reports the amount billed (cost / credits_cost), so a spend number is read per call instead of guessed at month end.
• Async by design. Submit, take the task_id, poll GET /v1/tasks/{id} — batching and retries are ordinary queue work, not a bespoke integration.

Nano Banana Pro is the highest-fidelity Gemini image route on APIMart: one asynchronous endpoint, 1K/2K/4K output, eleven aspect ratios including auto, and reference images for editing.

Endpoint: POST https://api.apimart.ai/v1/images/generations (OpenAI-compatible), then poll GET /v1/tasks/{task_id}. Result links are valid for 24 hours.

The token-billed official route bills per million tokens instead: text_input $1.60, cached_text_input free, image_input $1.60, cached_image_input free, text_output $9.60, image_output $96.00.

Prices are a snapshot; the pricing page and data/model.json are refreshed by CI, and a completed task reports the exact amount in its cost field.

Supported aspect ratios: auto, 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9.

curl --request POST --url https://api.apimart.ai/v1/images/generations \
  --header "Authorization: Bearer $APIMART_API_KEY" --header 'Content-Type: application/json' \
  -d '{"model":"gemini-3-pro-image-preview","prompt":"A bamboo forest path under moonlight","size":"1:1","resolution":"1K","n":1}'

import os, time, requests

BASE = "https://api.apimart.ai/v1"
HEADERS = {"Authorization": f"Bearer {os.environ['APIMART_API_KEY']}", "Content-Type": "application/json"}

created = requests.post(f"{BASE}/images/generations", headers=HEADERS, timeout=60, json={
    "model": "gemini-3-pro-image-preview", "prompt": "A bamboo forest path under moonlight",
    "size": "1:1", "resolution": "1K", "n": 1,
}).json()
task_id = created["data"]["id"]

while True:
    task = requests.get(f"{BASE}/tasks/{task_id}", headers=HEADERS, timeout=60).json()["data"]
    if task["status"] in ("completed", "failed"):
        break
    time.sleep(5)
print(task.get("cost"), task.get("result", {}).get("images", [{}])[0].get("url"))

const res = await fetch("https://api.apimart.ai/v1/images/generations", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.APIMART_API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({ model: "gemini-3-pro-image-preview", prompt: "A bamboo forest path under moonlight",
                          size: "1:1", resolution: "1K", n: 1 }),
});
const { data } = await res.json();      // data.id is the task id — poll /v1/tasks/<id>

Runnable versions: examples/. The task lifecycle is pending → processing → completed | failed, and the finished task carries cost, credits_cost and expiring result URLs.

Every render below came from a single call with the model id above, at the ratio shown; the cost column is what the task reported.

Output	Recipe	Ratio	Cost	Prompt
	Product / e-commerce	1:1	$0.03	Studio hero shot of a frosted glass perfume bottle on a wet black stone slab, single softbox from the left, faint mist, deep charcoal background, crisp label text, commercial product photography
	Cinematic still	16:9	$0.03	Rain soaked Kyoto alley at night, paper lantern reflections on wet stone, a lone figure with a transparent umbrella walking away, cinematic 35mm still, shallow depth of field, film grain
	Food photography	4:3	$0.03	Overhead flat lay of a spicy miso ramen bowl with soft boiled egg, nori and scallions, dark ceramic table, chopsticks resting on the rim, natural window light, editorial food photography
	Architecture	16:9	$0.03	Minimalist concrete villa on a cliff at dusk, warm interior light, infinity pool reflecting a violet sky, architectural photography, 24mm perspective, ultra sharp
	Illustration	1:1	$0.03	Layered paper cut illustration of a mountain lake at sunrise, five depth layers, soft pastel palette, subtle drop shadows, art print composition, clean vector edges
	Fashion portrait	3:4	$0.03	Editorial fashion portrait of a model in an oversized ivory wool coat, seamless light grey studio backdrop, crisp high key lighting, medium format detail, calm expression
	Macro nature	3:2	$0.03	Macro photograph of a dew covered dandelion seed head against deep black background, focus stacked detail, iridescent droplets, studio lighting
	Design / UI	16:9	$0.03	Flat vector dashboard panel showing three gauge dials and abstract latency curves, muted blue and sand palette, generous white space, crisp geometric cards, no placeholder text

Recipes and measured costs are also in data/samples.json.

What is the Nano Banana Pro API model id?

gemini-3-pro-image-preview. The alias nano-banana-pro-ext is documented as equivalent and produces identical results, so either string works in the model field.

How much does one Nano Banana Pro image cost?

On the per-image route the table above lists the effective price per resolution tier and the token-billed official route (gemini-3-pro-image-preview-official) is priced per million tokens; both are refreshed daily by CI and verified against the cost field of a completed task.

Can I generate more than one image per request?

No. n is 1 on this route; fan out client-side for batches. Passing a quoted number also fails — the field must be a bare integer.

How do I edit an existing image?

Send the source image in image_urls (public URL or base64 data URL) and describe what to preserve and what to change in prompt. With size: auto the output follows the upstream aspect ratio, so pin a ratio when the layout matters.

How long do the result links live?

The generated links are valid for 24 hours, so download and store the output as part of the job.

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Start with $1. Get an API key → check live pricing → open Nano Banana Pro (gemini-3-pro-image-preview) in the model library. The first call is three steps: submit, poll task_id, read the charged amount off the response.

Outbound APIMart links are minted through the promo link API; hand-made tracking parameters are rejected by tools/check_links.py in CI.

Nano Banana Pro is a third-party model served through APIMart; this repository documents how to call it and publishes real outputs, model ids and prices, and does not claim official status. Model names, prices and documentation belong to their respective owners. Endpoint reference: https://docs.apimart.ai/en/api-reference/images/gemini-3-pro/generation.

README.md             model id, pricing, parameters, quickstart, samples, FAQ
data/model.json       the pricing record for this model (CI-refreshed)
data/samples.json     prompt recipes with measured cost
tools/snapshot.py     refresh this model's prices from the public pricing payload
tools/check_links.py  attribution guard
examples/             curl, Python and JavaScript clients
assets/               real sample renders (JPEG, resized for the README)
.github/workflows/    daily price refresh + validation

MIT — see LICENSE.