# GPT Image 1.5 vs Nano Banana Pro: image API comparison guide

> Published 2026-04-01, updated 2026-09-05 · https://www.promptzone.com/xiu_hassan/gpt-image-vs-nano-banana-pro-ai-imaging-showdown-46jb

---
title: "GPT Image 1.5 vs Nano Banana Pro: image API comparison guide"
published: true
description: "Compare GPT Image 1.5 and Nano Banana Pro using documented access, image controls, and limitations, then design a fair test for your own workflow."
tags: ai, imagegeneration, generativeai, comparison
---
GPT Image 1.5 and Nano Banana Pro are hosted image-generation and editing models from OpenAI and Google DeepMind, respectively. Their API identifiers are `gpt-image-1.5` and `gemini-3-pro-image`; neither provides open weights for local deployment. Compare their output controls and results on your own task, while accounting for GPT Image 1.5's scheduled API retirement. [OpenAI model documentation][gpt], [Google developer announcement][prodev], and [OpenAI deprecation schedule][deprecations].

## What are the key facts about GPT Image 1.5 and Nano Banana Pro?

| Model | Developer | Released | Type | Size or parameters | License and access | Where it runs |
| --- | --- | --- | --- | --- | --- | --- |
| GPT Image 1.5. [Model page][gpt] | OpenAI. [Model page][gpt] | December 16, 2025, API release. [Changelog][oaichangelog] | Text and image inputs and outputs; the Image API returns image data. [Model page][gpt] and [API guide][openaiimages] | Not published in the model documentation. [Model page][gpt] | Hosted API; no open weights; deprecated with removal scheduled for December 1, 2026. [Model access][gpt] and [schedule][deprecations] | OpenAI-hosted Image API. [API guide][openaiimages] |
| Nano Banana Pro. [Model page][pro] | Google DeepMind. [Launch][prolaunch] | November 20, 2025. [Launch][prolaunch] | Text and image input and output. [Model page][pro] | Not published in the model documentation. [Model page][pro] | Hosted service under Google API terms; no open weights. [Terms][terms] and [access][prodev] | Google services including Gemini API, AI Studio, and Vertex AI. [Developer access][prodev] |

GPT Image 1.5 is deprecated, with API removal scheduled for December 1, 2026. OpenAI recommends GPT Image 2 as its replacement. Use this comparison to evaluate existing GPT Image 1.5 workflows, and account for that retirement when planning an integration. [OpenAI deprecation schedule][deprecations].

## What can GPT Image 1.5 and Nano Banana Pro do?

OpenAI documents GPT Image generation and editing through its Image API, including output-size and quality choices. GPT Image 1.5's model page lists separate image-generation prices for those settings. This makes the chosen output configuration a concrete part of a comparison. [OpenAI guide][openaiimages] and [GPT Image 1.5 settings][gpt].

Google documents Pro for compositions using visual references, text rendering, and creative control. Its model page also lists search grounding and thinking. Those are relevant capabilities when the desired asset combines a written brief with existing product or design imagery. [Pro developer guide][prodev] and [capabilities][pro].

Turn those features into testable tasks. For a product illustration, define the product details to preserve, the surrounding scene, and any exact text. For a poster, define the text hierarchy and the space needed for later layout work. Use the same acceptance criteria for both providers.

Keep aesthetic preference separate from compliance with the brief. You may prefer the color palette of one result while the other preserves the product more faithfully. Recording both judgments makes the eventual model choice easier to explain and avoids hiding a required detail behind a general quality score.

## What are the limitations and access restrictions?

OpenAI identifies text placement, visual consistency, and precise composition as continuing limitations of GPT Image models. Google's Pro guidance likewise identifies errors in small text, factual visuals, translation, and complex edits. Neither documentation supports treating every generated image as a finished production asset. [OpenAI limitations][openaiimages] and [Google limitations][prompting].

The cited model pages do not publish parameter counts. Both models are accessed as hosted services, so evaluate their API access requirements alongside the image task. [OpenAI model page][gpt] and [Google developer access][prodev].

This article reports no independent speed or image-quality benchmark. Do not interpret the capability table as measured superiority. A useful comparison must specify the task, the model identifiers, the settings, and how the outputs were judged.

If one request uses additional references or enabled search and the other does not, label that difference. You may still be comparing realistic workflows, but you should explain the input advantage instead of presenting the result as a controlled test of the models alone.

## How do you test GPT Image 1.5 and Nano Banana Pro?

For GPT Image 1.5, configure `OPENAI_API_KEY`, install the OpenAI Python SDK with `python -m pip install openai`, and call the Image API. [SDK and key setup][quickstart]. OpenAI says organization verification may be required to access GPT Image models. Use the example while your account retains access and before the documented retirement date. [Access requirements][openaiimages] and [deprecation schedule][deprecations]. This example selects the model explicitly and decodes the returned image data. [OpenAI image-generation guide][openaiimages].

```python
import base64
from pathlib import Path
from openai import OpenAI

result = OpenAI().images.generate(
    model="gpt-image-1.5",
    prompt="Create a poster for a ceramics show. Exact headline: CLAY FORMS.",
    size="1024x1024",
    quality="medium",
)
Path("openai-poster.png").write_bytes(
    base64.b64decode(result.data[0].b64_json)
)
```

For Pro, use a Google project with an API key configured as `GEMINI_API_KEY`. Google's current image guide documents the Interactions endpoint and image response configuration. The following request uses Pro's stable identifier and the same poster brief. [Google API guide][images] and [Pro model page][pro].

```bash
curl --fail-with-body \
  https://generativelanguage.googleapis.com/v1beta/interactions \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "model": "gemini-3-pro-image",
    "input": "Create a poster for a ceramics show. Exact headline: CLAY FORMS.",
    "response_format": {
      "type": "image", "mime_type": "image/png",
      "aspect_ratio": "1:1", "image_size": "1K"
    }
  }'
```

The Google request returns JSON containing image data; use the guide's response-handling example to save it. These two examples demonstrate access, not equivalent internal quality settings. Record the exact settings when you evaluate the pictures. [Google response handling][images].

Review the headline letter by letter, then inspect the layout and subject matter. Use anonymous filenames during selection if you want the visual review to focus on the result. After choosing, restore the model and request metadata so the preferred output remains traceable.

For an application integration, keep operational results as well: whether an image was returned, whether it met the brief, and what revision it needed. The sibling [Nano Banana Pro developer guide](/dalia_bernard/nano-banana-pro-googles-new-ai-tool-for-developers-517l) covers the Google integration in more detail.

## How do the two image APIs compare?

| Decision | GPT Image 1.5 | Nano Banana Pro |
| --- | --- | --- |
| Image API route | OpenAI Image API. [Guide][openaiimages] | Gemini image generation. [Guide][images] |
| Documented output controls | Size and quality settings. [Model page][gpt] | Image resolution and composition controls. [Developer guide][prodev] |
| Public self-hosting path | No open weights supplied. [Access][gpt] | No open weights supplied. [Access][prodev] |

Use the [ComfyUI guide](/tomas_novak/comfyui-2026-the-complete-guide-to-power-user-ai-image-generation-1g17) when deciding how the chosen service fits into a larger image workflow. Select a provider after testing the complete task, including review and revision. There is no documented basis here for a universal speed, cost, or quality winner.

## What else should you know before choosing an image API?

### Is Nano Banana Pro a local alternative to GPT Image?

No: Google's documented Pro access is hosted, just as the GPT Image API is hosted. Neither model supplies open weights for a local checkpoint workflow. [Google access][prodev] and [OpenAI access][gpt].

### Is GPT Image 1.5 still supported?

GPT Image 1.5 is deprecated and scheduled for API removal on December 1, 2026. OpenAI recommends GPT Image 2 for migration; this comparison concerns the documented GPT Image 1.5 API. [Deprecation schedule][deprecations].

### Which model is better at text inside images?

Both providers document relevant capabilities and remaining text-rendering limitations. Test your exact copy and layout, then count the corrections needed rather than assuming a universal winner. [OpenAI limitations][openaiimages] and [Google limitations][prompting].

### Can I compare image prices without matching settings?

Treat such a comparison as incomplete. Record the model, requested output, reference inputs, and revision workload before deciding which service is less expensive for your task.

## Sources

Primary sources checked on September 5, 2026.

- [OpenAI GPT Image 1.5 model documentation][gpt]
- [OpenAI API changelog][oaichangelog]
- [OpenAI model deprecation schedule][deprecations]
- [OpenAI image-generation guide][openaiimages]
- [OpenAI Python SDK and API-key quickstart][quickstart]
- [Google model documentation for Gemini 3 Pro Image][pro]
- [Google announcement of Nano Banana Pro][prolaunch]
- [Google developer guide to the Nano Banana Pro launch][prodev]
- [Google Gemini API terms][terms]
- [Google prompting guidance and limitations for Nano Banana Pro][prompting]
- [Google Gemini API image-generation documentation][images]

[gpt]: https://developers.openai.com/api/docs/models/gpt-image-1.5
[deprecations]: https://developers.openai.com/api/docs/deprecations
[oaichangelog]: https://developers.openai.com/api/docs/changelog
[openaiimages]: https://developers.openai.com/api/docs/guides/image-generation
[quickstart]: https://developers.openai.com/api/docs/quickstart
[pro]: https://ai.google.dev/gemini-api/docs/models/gemini-3-pro-image
[prolaunch]: https://blog.google/innovation-and-ai/products/nano-banana-pro/
[prodev]: https://blog.google/innovation-and-ai/technology/developers-tools/gemini-3-pro-image-developers/
[terms]: https://ai.google.dev/gemini-api/terms
[prompting]: https://blog.google/products-and-platforms/products/gemini/prompting-tips-nano-banana-pro/
[images]: https://ai.google.dev/gemini-api/docs/image-generation

<!-- pz-related-guides -->
## Related guides on PromptZone

- [Best SDXL Models in 2026](/tara_suzuki/best-sdxl-models-in-2026-realistic-anime-and-all-purpose-checkpoints-116)
- [ComfyUI 2026: The Complete Guide](/tomas_novak/comfyui-2026-the-complete-guide-to-power-user-ai-image-generation-1g17)
- [AI Model Releases Timeline](/ai-model-releases)