Gemini 3.1 Flash Image (preview), marketed as Nano Banana 2, delivers high-quality image generation and conversational editing at low latency as the high-efficiency counterpart to Nano Banana Pro, and Google's guide calls it the generalist workhorse of the image family, balancing speed with 4K generation, world knowledge, and reliable text rendering.
- Input
- text image $0.5/M
- Output
- image text $60/M
- Knowledge cutoff
- 2025-01
Price in context
Where the price sits among 8 comparable models
The bar shows how this model’s price compares with every other model of the same kind on Synthorai. The cheapest and the most expensive are named at each end. These are base rates; batch, region and cache-write discounts are on the pricing page.
Specs & limits
Tokens
| Max output (vendor spec) | 32,768 |
|---|---|
| Knowledge cutoff | 2025-01 |
Thinking
| Vendor control | thinking_level |
|---|---|
| Accepted values | minimal · high |
| Default | minimal applied when the request sets nothing |
| Can be turned off | No |
| Thinking behaviour | Thinking is on by default and cannot be disabled in the API; thinking tokens are billed whether or not you read the thought summaries, and interim thought images are not charged. |
| Parameter | reasoning_effort |
| Values | minimal · low · medium · high the gateway's parameter surface - the vendor mapping above applies |
Image
| Sizes |
|
|---|---|
| Input modes | text-to-image, image editing, up to 14 reference images |
| Image capabilities |
|
Model
| Modalities | text + image → image + text |
|---|
- Gateway preview id has no live official page
- GA model code is gemini-3.1-flash-image (released 2026-05-28)
- caching, function calling, structured outputs not supported
Use Gemini 3.1 Flash Image 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-3.1-flash-image-preview",
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-3.1-flash-image-preview",
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-3.1-flash-image-preview",
"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-3.1-flash-image-preview",
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-3.1-flash-image-preview")
.prompt("a watercolor lighthouse at dawn")
.size("1024x1024")
.build());
System.out.println(resp.data().orElseThrow().get(0).b64Json().orElseThrow().substring(0, 80));About Gemini 3.1 Flash Image
- Versus the earlier Nano Banana generation, the official page highlights expanded resolution support (0.5K, 1K, 2K, and 4K), new extreme aspect ratios such as 1:4 and 8:1 that widen the set to fourteen, Image Search Grounding that blends web text and image results, and improved aspect-ratio adherence, image consistency, and international text rendering.
- Input tokens reach 131,072, twice the Pro tier's, with 32,768 output.
- It accepts up to ten object reference images at high fidelity and four character references for consistency, and supports thinking through thinking_level at minimal or high, with those tokens billed either way.
- Image Search Grounding is requested through search_types and returns citation annotations alongside the render.
- It is also the only model in the family that takes video, including a public YouTube URL, as context, which is how Google documents thumbnail generation.
- Editing spans multi-turn refinement, semantic masking, style transfer, and multi-image composition, and batch processing is supported.
- Synthorai serves the model over its OpenAI-compatible API surface.
FAQ
Is the Gemini 3.1 Flash Image API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. That's enough to try Gemini 3.1 Flash Image against your real workload before adding a payment method.
What is Gemini 3.1 Flash Image best at?
Expanded resolution from 0.5K to 4K; extreme aspect ratios like 1:4 and 8:1; image search grounding blends web results. See the About section for the full picture from the vendor's own release notes.
How much does Gemini 3.1 Flash Image cost?
Gemini 3.1 Flash Image costs $0.5 per million input tokens and $60 per million output tokens on Synthorai. That is the provider's list price, with no platform markup.
How do I generate images with the Gemini 3.1 Flash Image API?
POST to /v1/images/generations on Synthorai with model="gemini-3.1-flash-image-preview". It follows the OpenAI images API shape, so no vendor SDK is needed. Supported sizes: 512px (0.5K), 1K (default; 1:1 = 1024x1024), 2K (2048x2048), 4K (4096x4096).
How do I get access to Gemini 3.1 Flash Image?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="gemini-3.1-flash-image-preview", and you're done. One API key covers every model on the gateway.
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Every value on this page is transcribed from the vendor's own documentation, linked above, and carries the date it was checked. Prices are compared across the catalogue; specification values that vendors define differently are shown with the difference stated rather than charted. Nothing here is measured by us, and nothing is scored.