Nano Banana Pro API

Nano Banana Pro is Google's precision-focused image model for visual tasks that are difficult to solve with a fast, general-purpose generator. On GPTProto, developers can access it through the gemini-3-pro-image-preview model string and generate images from text prompts without maintaining a separate provider balance. The current rate starts at $0.0804 per generation, a 40% reduction from the $0.134 reference price shown on the page.

What Is the Nano Banana Pro API?

Nano Banana Pro is the product name for Gemini 3 Pro Image. It is not the general Gemini 3 Pro language-model endpoint. The image model uses an internal reasoning process to plan composition before producing the final render, which makes it a better fit for dense layouts, exact relationships between objects, and designs that combine imagery with readable text.

Google documents 1K, 2K, and 4K output, image generation and editing, multilingual text rendering, and multiple aspect ratios for the underlying model. This GPTProto page is currently labeled text-to-image, so use the controls and parameters exposed in the GPTProto documentation for this route. If image upload, multi-image composition, or search grounding is added to the route later, document those inputs separately instead of implying that every official capability is already available here.

Where Nano Banana Pro Fits Best

Posters, Packaging, and Marketing Graphics

Use Nano Banana Pro when words are part of the image rather than a caption added afterward. A prompt can define the exact headline, supporting copy, font character, visual hierarchy, and placement for posters, product labels, menus, event graphics, and campaign concepts. Generated text should still be reviewed before publication, especially for legal copy, prices, dates, and small print.

Product Mockups and Ecommerce Concepts

The model can interpret instructions about product position, camera angle, surface material, lighting direction, background, reflections, and surrounding props in one request. This is useful for testing hero images, seasonal campaign directions, packaging ideas, and listing concepts before committing to photography or a full design pass.

Infographics and Explanatory Visuals

Nano Banana Pro is a strong option for diagrams, educational graphics, process illustrations, and data-led visual concepts that require both scene logic and typographic structure. Give the model the facts to display, define the sections and reading order, and verify every generated label or number before using the result as factual content.

Storyboards and Multi-Element Compositions

Choose the Pro model for prompts that specify several people, objects, panels, or spatial constraints. State the number of elements, where each element belongs, and which details must remain visually distinct. This gives the reasoning stage a clearer plan and reduces missing objects, duplicated elements, and accidental layout changes.

Nano Banana Pro vs Nano Banana 2, GPT Image 2, and Seedream 5.0 Pro

There is no single best image API for every workload. The useful distinction is the kind of failure you need to avoid: slow iteration, weak text layout, inconsistent editing, or limited spatial control.

For most high-volume applications, Nano Banana 2 is the more economical default. Route only the hardest poster, infographic, product-hero, or multi-element requests to Nano Banana Pro. Because GPTProto provides these models under one account, you can test this routing strategy without managing a separate key and credit balance for every provider.

How to Write a Better Nano Banana Pro Prompt

A useful Nano Banana Pro prompt behaves like a compact creative brief. Put requirements in a predictable order:

1. Task and format: State whether the output is a poster, product mockup, infographic, storyboard, or another asset, followed by its aspect ratio.

2. Subject and scene: Name the main subject, environment, camera angle, and depth relationship.

3. Exact text: Put required wording in quotation marks and define headline, subheading, label, and footer placement.

4. Layout rules: Describe sections, alignment, spacing, object count, and reading order.

5. Visual direction: Specify palette, materials, lighting, lens or illustration style, and intended audience.

6. Locked constraints: End with details that must not change and a short list of unwanted additions.

Example prompt

Create a 4:5 premium skincare launch poster. Place one frosted-glass serum bottle in the lower center on pale limestone, photographed from a slightly low three-quarter angle. Add the exact headline "CALM, CLARIFIED." at the upper left in large dark-green serif type and the subheading "Barrier support for stressed skin" directly below it in a smaller sans-serif. Use soft morning side light, restrained sage and ivory tones, realistic condensation, and generous negative space. Keep the bottle label fully visible. Do not add extra products, badges, logos, or text.

If the output misses a requirement, revise one category at a time. Correct the text and hierarchy first, then object placement, and finally style details. Rewriting the entire prompt after every attempt makes it harder to identify which instruction improved or damaged the result.

Why Access Nano Banana Pro on GPTProto?

GPTProto lists Nano Banana Pro from $0.0804 per generation, which is 40% below the $0.134 reference rate displayed on the page. The larger operational benefit is model choice: one API key and one balance can also cover Nano Banana 2, GPT Image 2, Seedream models, and other image APIs. Teams can route routine generations to a faster or lower-cost model and reserve Nano Banana Pro for the requests where typography, composition, or instruction density justifies it.