Gemini Nano Banana 2.1

Specs & limits

• Reached GA on 2026-10-06 as the update to Nano Banana 2 (gemini-3.1-flash-image)
• the release note cites better visual quality, prompt adherence, multi-turn character consistency, text rendering and wide and panoramic aspect ratios at Flash-level speed and cost. Thinking is always on, with minimal, medium (default) and high levels
• function calling and structured outputs are not supported
• temperature, top_p, top_k and seed are not accepted. Billed per token at three rates: input, image output, and text and reasoning output
• an output image is 1,120 tokens at 1K, 1,680 at 2K and 3,780 at 4K, and a reference image is 1,120 input tokens

per Google official docs ↗

One prompt, measured through the gateway

PROMPT A weathered enamel diner mug on a steel counter, the words "OPEN 24H" stencilled on the mug in worn paint, low winter sun raking in from the left, shallow depth of field.

Gemini Nano Banana 2.1

Model returned 1376×768 latency 11 s

One prompt, one request per model, no retries and no cherry-picking. This is the first result each model returned. Neither size nor duration was pinned: each model used its own default, because a request shaped to fit all of them would flatter none. Files here are re-encoded for the web, so judge composition and prompt adherence, not compression.

Use Gemini Nano Banana 2.1 in 30 seconds

OpenAI-compatible: swap the base_url, keep your SDK. POST /v1/images/generations

from openai import OpenAI

client = OpenAI(
    base_url="https://synthorai.io/v1",
    api_key="sk-syn-...",
)

resp = client.images.generate(
    model="gemini-nano-banana-2.1",
    prompt="a watercolor lighthouse at dawn",
    size="1024x1024",
)
print(resp.data[0].b64_json[:80])

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://synthorai.io/v1",
  apiKey: "sk-syn-...",
});

const resp = await client.images.generate({
  model: "gemini-nano-banana-2.1",
  prompt: "a watercolor lighthouse at dawn",
  size: "1024x1024",
});
console.log(resp.data?.[0]?.b64_json?.slice(0, 80));

curl https://synthorai.io/v1/images/generations \
  -H "Authorization: Bearer sk-syn-..." \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-nano-banana-2.1",
    "prompt": "a watercolor lighthouse at dawn",
    "size": "1024x1024"
  }'

package main

import (
	"context"
	"fmt"

	"github.com/openai/openai-go/v3"
	"github.com/openai/openai-go/v3/option"
)

func main() {
	client := openai.NewClient(
		option.WithBaseURL("https://synthorai.io/v1"),
		option.WithAPIKey("sk-syn-..."),
	)
	resp, _ := client.Images.Generate(context.TODO(), openai.ImageGenerateParams{
		Model:  "gemini-nano-banana-2.1",
		Prompt: "a watercolor lighthouse at dawn",
		Size:   "1024x1024",
	})
	fmt.Println(resp.Data[0].B64JSON[:80])
}

import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.images.*;

OpenAIClient client = OpenAIOkHttpClient.builder()
    .baseUrl("https://synthorai.io/v1")
    .apiKey("sk-syn-...")
    .build();

ImagesResponse resp = client.images().generate(
    ImageGenerateParams.builder()
        .model("gemini-nano-banana-2.1")
        .prompt("a watercolor lighthouse at dawn")
        .size("1024x1024")
        .build());
System.out.println(resp.data().orElseThrow().get(0).b64Json().orElseThrow().substring(0, 80));

About Gemini Nano Banana 2.1

• Google's release note says it keeps Flash-level speed and cost efficiency while improving visual quality, prompt adherence, multi-turn character consistency, text rendering, and wide and panoramic aspect ratios.
• Output comes in 1K, 2K and 4K at fifteen aspect ratios, from 1:1 and 16:9 to the panoramic 1:4, 4:1, 1:8 and 8:1, and a single request can carry up to 14 reference images.
• It accepts text, image, video and PDF input with a 131,072-token input limit and returns image and text; editing works in a single turn or as a multi-turn conversation.
• Thinking is always on, with minimal, medium and high levels and medium as the default, while function calling and structured outputs are not supported.
• It is priced per token at three rates: $1.50 per million input tokens, $30 per million image output tokens, and $7.50 per million tokens of text and reasoning output, which puts a 1K image at about $0.034, a 2K image at $0.05 and a 4K image at $0.113.
• Synthorai serves it through the images endpoint, billed per token.

FAQ

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