Nano Banana API: Gemini 2.5 Flash Image, Specs and Pricing
Nano Banana is Google Gemini 2.5 Flash Image. It generates and edits images with character consistency, ten aspect ratios, and up to 20 reference images.
Nano Banana is Google's official short name for Gemini 2.5 Flash Image, a fast text-to-image and image-editing model with strong character consistency, multi-image fusion, and natural-language editing. It went generally available in October 2025. On Unifically the standard variant is $0.03 per image, with up to 20 optional reference images and ten aspect ratios per call.
TL;DR: Nano Banana is Gemini 2.5 Flash Image. It accepts a prompt plus up to 20 reference images (10 MB max each) and supports ten aspect ratios from 1:1 through 21:9. The standard variant is $0.03 per image on Unifically. Two siblings exist for higher resolution: Nano Banana 2 (resolution-priced Gemini 2.5 Flash Image) and Nano Banana Pro (Gemini 3 Pro Image, up to 4K). Live rates: pricing page.
What is Nano Banana?
Nano Banana is Google's nickname (and now official short name) for the Gemini 2.5 Flash Image model. It generates new images from a prompt, edits existing images using natural language, and blends multiple reference images into a single composition. It became generally available in October 2025 through the Gemini API, AI Studio, and Vertex AI.
The model is known for four capabilities Google highlighted at launch:
- Character consistency. Keeps the same person or object recognisable across multiple prompts and edits.
- Multi-image fusion. Blends up to 14 reference images into a single output (Pro) or up to 20 references on Unifically's route.
- Prompt-based editing. Change specific parts of an image using natural-language instructions.
- Visual template adherence. Follows a fixed layout (employee badges, real-estate cards, product mockups) across many generations.
Every Nano Banana output carries Google's invisible SynthID watermark for AI-content provenance.
What Nano Banana solved
Nano Banana fixed two things at once that had kept earlier text-to-image models out of production work:
- Character identity drift. Before Nano Banana, asking a model to render the same character in three different scenes typically returned three different faces. Gemini 2.5 Flash Image holds identity stably across prompts.
- Conversational editing. "Change the background to a sunset beach" or "give the person a winter coat" works as a one-shot edit, not a long prompt-engineering session.
That combination opened up product workflows that previously required expensive retouchers: catalogue stills with one consistent model across many scenes, branded character series, and template-driven assets like agent badges.
What you can do with Nano Banana
Inputs
- Prompt. Required text describing the image.
- Reference images. Up to 20 optional URLs, each up to 10 MB. Used for subject consistency, style transfer, or multi-image fusion.
- Aspect ratio. Choose from ten ratios spanning 1:1 through 21:9.
Output
- A single image at the chosen aspect ratio.
- SynthID invisible watermark embedded for AI provenance.
- Returned via task-based async polling.
Variants on Unifically
Three Nano Banana endpoints exist. Pick by what you need.
| Variant | Underlying model | Resolution control | Per-image price |
|---|---|---|---|
| Nano Banana | Gemini 2.5 Flash Image | single variant | $0.03 |
| Nano Banana 2 | Gemini 2.5 Flash Image | 1K, 2K, or 4K | $0.03 / $0.05 / $0.06 |
| Nano Banana Pro | Gemini 3 Pro Image | 1K or 2K | $0.06 |
Use Nano Banana when you do not need explicit resolution selection and want the cheapest list price. Use Nano Banana 2 when the workflow needs a 1K-draft / 4K-final flow at predictable per-resolution pricing. Use Nano Banana Pro when you want Gemini 3 Pro's stronger text rendering and reasoning.
Nano Banana pricing and how it compares
| Source | Variant | Per-image price |
|---|---|---|
| Unifically | Nano Banana | $0.03 |
| Unifically | Nano Banana 2 1K | $0.03 |
| Unifically | Nano Banana 2 2K | $0.05 |
| Unifically | Nano Banana 2 4K | $0.06 |
| Google direct (Gemini API / Vertex AI) | Gemini 2.5 Flash Image | ~$0.039 ($30 per 1M output tokens, ~1,290 tokens per image) |
Source: Google Developers Blog and Vertex AI pricing for Gemini 2.5 Flash Image. Unifically's $0.03 base rate beats Google's direct list price by roughly 23% per image.
How to call Nano Banana
The API is async: POST a generation, then poll until the image URL is ready.
const API = 'https://api.unifically.com';
const headers = {
Authorization: `Bearer ${process.env.UNIFICALLY_API_KEY}`,
'Content-Type': 'application/json',
};
const start = await fetch(`${API}/nano-banana/generate`, {
method: 'POST',
headers,
body: JSON.stringify({
prompt: 'A studio portrait of the same character from the reference image, now wearing a wool coat in a snowy alley',
aspect_ratio: '4:5',
image_urls: ['https://example.com/character-reference.jpg'],
}),
}).then((r) => r.json());
while (true) {
await new Promise((r) => setTimeout(r, 2000));
const task = await fetch(`${API}/v1/tasks/${start.task_id}`, { headers }).then((r) => r.json());
if (task.status === 'completed') {
console.log(task.image_url);
break;
}
if (task.status === 'failed') throw new Error(task.error);
}
Switch the path to /nano-banana-2/generate or /nano-banana-pro/generate for the higher-resolution siblings.
Things to know
- Stuffing 20 references when you only need 2. Reference images compete for influence. Over-loading dilutes the effect of the most important one. Send the minimum that anchors the look.
- Asking for absurd aspect ratios for editing. Nano Banana works best at the ten supported ratios (1:1 through 21:9). Forcing exotic dimensions through cropping after the fact gives better results than fighting the model.
- Treating SynthID as optional. The invisible watermark is always embedded. If your downstream pipeline strips metadata, you lose the AI provenance signal, so keep it for compliance.
- Defaulting to Pro for everything. Pro doubles the per-image cost. Start on Nano Banana for drafts. Promote to Nano Banana 2 4K or Pro only when the result survives review.
- Using Nano Banana for legible long-form text rendering. Short text usually works. Long paragraphs of in-image type are still better handled by Nano Banana Pro (Gemini 3 Pro Image), which Google specifically tuned for text rendering.
Frequently asked questions
What is Nano Banana?
Nano Banana is Google's Gemini 2.5 Flash Image model. It generates and edits images from natural-language prompts, holds character identity across edits, fuses up to 20 reference images, and includes a SynthID invisible watermark. It went generally available in October 2025.
How much does Nano Banana cost?
On Unifically the base Nano Banana variant is $0.03 per image. Nano Banana 2 is priced by resolution: $0.03 at 1K, $0.05 at 2K, $0.06 at 4K. Nano Banana Pro (Gemini 3 Pro Image) is $0.06 per image. Google direct lists Gemini 2.5 Flash Image at roughly $0.039 per image. Check the pricing page for current rates.
What aspect ratios does Nano Banana support?
Ten aspect ratios from 1:1 through 21:9, including portrait, landscape, square, and ultrawide options. The aspect ratio is set per generation request alongside the prompt and any reference images.
Can Nano Banana keep the same character across generations?
Yes. Character consistency is one of Nano Banana's core capabilities. Pass a reference image of the subject, then prompt new scenes; the model preserves facial features, body proportions, and distinctive traits across separate runs.
When should I use Nano Banana 2 or Nano Banana Pro instead?
Use Nano Banana 2 when you want explicit 1K, 2K, or 4K resolution control with resolution-priced variants. Use Nano Banana Pro when you need Gemini 3 Pro's stronger text rendering and multi-turn reasoning for studio-grade work.
Related reading
- Nano Banana model page: live playground at the $0.03 variant.
- Nano Banana 2: resolution-priced Gemini image generation.
- Nano Banana Pro: Gemini 3 Pro Image at 1K or 2K.
- GPT Image 2 and Flux.2: other image APIs on Unifically.
