nano banana

Nano Banana (`gemini-2.5-flash-image`) Model Card #

Overview #

Nano Banana (gemini-2.5-flash-image) is Google's foundational image generation model in the Gemini family. It introduced conversational image generation and editing at a fixed 1024px resolution.

Model Code: gemini-2.5-flash-image
Release Date: October 2, 2025 (GA)
Retirement Date: October 2, 2026 (Migration recommended to Nano Banana 2 Lite)
Status: General Availability (GA)

Technical Specifications #

Property	Value
Input Modalities	Text, Images (up to 3), PDF (up to 3 pages)
Output Modalities	Image and Text
Input Token Limit	65,536 tokens
Output Token Limit	32,768 tokens
Image Generation Cost	Fixed at 1,290 tokens per image
Max Resolution	1K only (1024px bounding box; 2K/4K unsupported)
Aspect Ratios	10 standard ratios
Thinking Mode	❌ Not Supported
Search Grounding	❌ Not Supported
Video Context	❌ Not Supported
Function Calling	❌ Not Supported
Watermarking	SynthID (Always On) + C2PA Metadata

Supported Aspect Ratios & Output Dimensions (1K Fixed) #

Aspect Ratio	Output Dimensions	Token Cost
`1:1`	1024 × 1024	1,290
`2:3`	832 × 1248	1,290
`3:2`	1248 × 832	1,290
`3:4`	864 × 1184	1,290
`4:3`	1184 × 864	1,290
`4:5`	896 × 1152	1,290
`5:4`	1152 × 896	1,290
`9:16`	768 × 1344	1,290
`16:9`	1344 × 768	1,290
`21:9`	1536 × 672	1,290

Model Comparison: Nano Banana vs Banana 2 Family #

Feature	Nano Banana (`gemini-2.5-flash-image`)	Nano Banana 2 Lite (`gemini-3.1-flash-lite-image`)	Nano Banana 2 (`gemini-3.1-flash-image`)
Latency	~4–6s	< 2s	~3–5s
Resolutions	1K only	1K only	512px, 1K, 2K, 4K
Aspect Ratios	10 standard	14 discrete	14 discrete
Search Grounding	❌ None	❌ None	Web & Image Search
Reference Images	Up to 3	Up to 14	Up to 14
Thinking Support	❌ None	`minimal`, `high`	`minimal`, `high`

API Code Example #

python

import base64
from google import genai

client = genai.Client()

interaction = client.interactions.create(
    model="gemini-2.5-flash-image",
    input="A high-contrast ink sketch of a mountain pass at dawn",
    response_format={
        "type": "image",
        "mime_type": "image/png",
        "aspect_ratio": "16:9",
    },
)

if interaction.output_image:
    with open("mountain.png", "wb") as f:
        f.write(base64.b64decode(interaction.output_image.data))

Nano Banana (gemini-2.5-flash-image) Model Card #