Google: Nano Banana Pro (Gemini 3 Pro Image) vs OpenAI: GPT Image 2.5 Sunburst
A side-by-side comparison of Google: Nano Banana Pro (Gemini 3 Pro Image) ($7.00 / 1M tokens) and OpenAI: GPT Image 2.5 Sunburst ($28.00 / 1M tokens) using current USD prices and capabilities from the api14 catalog. Both run through the same OpenAI-compatible API.
Specifications
| Google: Nano Banana Pro (Gemini 3 Pro Image) | OpenAI: GPT Image 2.5 Sunburst | |
|---|---|---|
| Provider | OpenAI | |
| Input | $7.00 / 1M tokens | $28.00 / 1M tokens |
| Output | $42.00 / 1M tokens | $28.00 / 1M tokens |
| Cache read | $0.70 / 1M tokens | $7.00 / 1M tokens |
| Cache write | $1.31 / 1M tokens | - |
| Reasoning | $42.00 / 1M tokens | - |
| Image output | $420.00 / 1M tokens | $105.00 / 1M tokens |
| Audio input | $7.00 / 1M tokens | - |
| Image | $0.000007 / image | - |
| Web search | $49.00 / 1K searches | $35.00 / 1K searches |
| Context window | 131,072 | 400,000 |
| Max output | 32,768 | 360,000 |
| Input | image, text | text, image |
| Output | image, text | image |
| Tool calling | ||
| Structured output | ||
| Reasoning control | ||
| Added | Jun 18, 2026 | Sep 9, 2026 |
Key differences
- Google: Nano Banana Pro (Gemini 3 Pro Image) is 75% cheaper on input tokens.
- OpenAI: GPT Image 2.5 Sunburst is 33% cheaper on output tokens.
- OpenAI: GPT Image 2.5 Sunburst reads 3.1× more context (400,000 tokens).
- Only Google: Nano Banana Pro (Gemini 3 Pro Image) supports tool calling.
- Only Google: Nano Banana Pro (Gemini 3 Pro Image) supports reasoning effort control.
In depth
Google: Nano Banana Pro (Gemini 3 Pro Image) is an image model from Google, listed under the model id google/gemini-3-pro-image. OpenAI: GPT Image 2.5 Sunburst is an image model from OpenAI, listed under the model id openai/gpt-image-2.5-sunburst. Both sit in the image category on api14, so they are aimed at the same broad kind of work, and the choice between them comes down to how each one handles context, output and the parameters you need.
The clearest split is context and output. GPT Image 2.5 Sunburst has the bigger context window, at 400000 tokens against 131072 for Nano Banana Pro, so it can take in far more material in a single call. Both accept text and image as input, but their outputs differ: Nano Banana Pro returns image and text, while GPT Image 2.5 Sunburst returns image only. On parameters, Nano Banana Pro is the only one of the two that supports tools, tool choice and reasoning (including include_reasoning), and it also exposes temperature, top_p, stop and seed. GPT Image 2.5 Sunburst supports a narrower set: max_tokens, response_format, seed and structured_outputs. Structured outputs are available on both, so that is not a deciding factor. On price, Nano Banana Pro is the cheaper of the two for input, while GPT Image 2.5 Sunburst is the cheaper for output, so the better value depends on whether your workload is input heavy or output heavy.
For practical work, pick Nano Banana Pro when you need the model to call tools, when you want reasoning surfaced or controlled through the reasoning parameters, or when you need text alongside the generated image in the response. It also suits input heavy jobs where the lower input price matters, as long as 131072 tokens of context is enough. Pick GPT Image 2.5 Sunburst when your prompts or reference material are large and you need the bigger context window, or when output volume dominates your usage and the lower output price is the main concern. If you only need an image back and do not need tools or reasoning, its narrower parameter set is not a limitation.
Calling either model through api14 works the same way, because the API is OpenAI compatible. You send your request to the same endpoint with the same request shape, and the only thing you change is the model id: use google/gemini-3-pro-image for Nano Banana Pro, or openai/gpt-image-2.5-sunburst for GPT Image 2.5 Sunburst. Keep the parameters within what each model supports, since tools and reasoning belong to Nano Banana Pro while the wider context belongs to GPT Image 2.5 Sunburst.
There are cases where the second choice is still the better one. If your task needs a very large amount of input context, GPT Image 2.5 Sunburst is the only option of the two with the bigger window, and if your costs are driven mostly by output, its lower output price makes it the more economical pick even though Nano Banana Pro is cheaper on input.
Switch with one string
Both models use the same endpoint and request shape. Change the model value from "google/gemini-3-pro-image" to "openai/gpt-image-2.5-sunburst" and prompts, streaming and tools keep working.
import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://api14.com/api/v1",
apiKey: process.env.API14_API_KEY,
});
const result = await client.images.generate({
"model": "openai/gpt-image-2.5-sunburst",
"prompt": "A minimalist product photo of a ceramic mug on a wooden table",
"n": 1,
"aspect_ratio": "1:1"
});
import { writeFile } from "node:fs/promises";
await writeFile("image.png", Buffer.from(result.data[0].b64_json, "base64"));
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