How to Make NanoBanana Images in Your Own Aspect Ratio

If you want NanoBanana images to match a specific size ratio—such as 1:1, 4:5, 16:9, or a custom banner shape—the key is to define the framing clearly before generation and use the model’s ratio controls during output. This guide shows you how to choose the right aspect ratio, write prompts that support it, and refine the result without breaking composition.

1) Start With the Right Aspect Ratio

Conclusion: The cleanest way to get the image you want is to decide the ratio first, then generate with that framing in mind.

NanoBanana supports ratio-based generation, so you should treat aspect ratio as part of your creative brief, not an afterthought. A square image works well for profile visuals, a vertical ratio fits social posts or posters, and a wide ratio is better for banners, headers, and cinematic scenes.

Practical advice:

• Decide the final use case before prompting.
• Pick the ratio that matches the destination platform.
• Mention framing in the prompt so the subject is composed correctly.

Common ratio choices

Use case	Suggested ratio	Why it helps
Social avatar or product tile	1:1	Balanced, compact composition
Instagram-style post	4:5	Strong vertical presence
Story or portrait image	9:16	Full-height mobile layout
Website hero banner	16:9	Wide visual space for headlines
Presentation cover	16:10	Clean widescreen layout

2) Write Prompts That Support the Ratio

Conclusion: A good ratio setting is not enough by itself—you also need prompt language that reinforces composition.

NanoBanana is designed for text/image-to-image generation, so you can guide the model with clear instructions about subject placement, empty space, and scene structure. If you want a wide image, say so. If you need room for text, ask for negative space. If you want a portrait layout, describe a vertical composition.

What to include in your prompt:

• Subject placement: centered, left-aligned, upper third, etc.
• Composition style: close-up, full-body, wide scene, poster layout.
• Space requirements: leave blank space for text or cropping.
• Content priority: what must remain visible in the final output.

Example prompt patterns:

• “Create a wide 16:9 hero image with the main subject placed on the left and open space on the right for headline text.”
• “Generate a square 1:1 product image with centered composition and clean background.”
• “Design a vertical 4:5 poster layout with the subject in the upper half and room below for copy.”

Practical advice:

• Use direct framing terms like “wide banner,” “portrait poster,” or “square layout.”
• Avoid vague prompts if ratio matters.
• Add negative space instructions when you plan to overlay text later.

3) Use References to Keep the Composition Stable

Conclusion: If you want your chosen ratio to remain consistent across edits or multiple versions, reference images help stabilize the structure.

According to the workflow, NanoBanana lets you add prompts and up to 14 reference images. This is useful when you need a specific layout, brand style, or character arrangement across different aspect ratios. References help the model understand what should stay consistent while adapting to a new frame.

When references help most:

• Reusing a product angle in a different ratio
• Keeping a character consistent across poster and banner versions
• Matching brand style across campaign sizes
• Adapting a scene from square to wide without losing the main subject

Practical advice:

• Provide a reference that already resembles your desired framing.
• Use references with clear subject placement.
• If the output feels cramped, simplify the prompt and keep only the most important visual cues.

4) Refine the Canvas Instead of Rebuilding Everything

Conclusion: If the ratio is close but not perfect, semantic editing is often better than starting over.

NanoBanana supports smart edits such as repainting, extending scenes, removing marks, and adjusting details while keeping lighting aligned. That means you can preserve the original composition and expand or trim it to fit a target ratio more naturally.

Useful edit actions:

• Extend the canvas to create a wider or taller frame
• Replace or remove objects that distract from the composition
• Repaint specific areas to improve balance
• Adjust spacing so the subject sits better inside the new ratio

Practical advice:

• Generate a strong base image first.
• Then use semantic editing to adapt it to the final frame.
• Focus edits on the edges of the composition when changing ratios.

5) Choose the Output Size That Matches Your Final Use

Conclusion: Aspect ratio and resolution should work together, not separately.

NanoBanana supports 1K, 2K, and 4K outputs, so once your ratio is correct, you can choose the resolution based on how the image will be used. A large banner or print-style asset may need more detail, while a web thumbnail may not.

Practical advice:

• Use lower resolution for quick iteration.
• Use higher resolution for final marketing assets or detailed visuals.
• Keep the same ratio across the generation and export stages.

Simple workflow for custom-size images

1. Define the final aspect ratio.
2. Write a prompt that matches the intended framing.
3. Add reference images if you need consistency.
4. Generate the first version.
5. Refine with semantic editing if the composition needs adjustment.
6. Export in the resolution that fits your use case.

FAQ

Can I make NanoBanana images in any aspect ratio?

You can choose the ratio during generation, and the model supports flexible framing for different use cases. For best results, define the ratio clearly in the prompt and select the matching output format.

What is the best aspect ratio for social media?

It depends on the platform and placement. Square and vertical ratios are common for social posts, while wide ratios are better for banners and cover images.

How do I keep the subject from getting cut off?

Ask for a composition that leaves breathing room around the subject, and use semantic editing or canvas extension if the image needs to be adapted to a new frame.

Can I resize an image after generating it?

Yes, but resizing alone may crop important details. It is usually better to generate with the target ratio or refine the image using canvas extension or semantic editing.

Do reference images help with aspect ratio control?

Yes. References can help maintain layout consistency, subject placement, and style when generating multiple versions in different sizes.

Summary

To make NanoBanana images in your own size ratio, start by choosing the final frame, then guide the model with clear composition instructions. Use references to keep layouts consistent, and rely on semantic editing when you need to extend or adjust the canvas. Once the ratio is right, choose the output resolution that fits your final use.

In short: set the ratio first, write for the frame, refine when needed, and export at the right size.