Nano Banana vs Seedream 4.0 — Which AI Image Generator Wins the 1-2 s Race?
2025/09/12

Nano Banana vs Seedream 4.0 — Which AI Image Generator Wins the 1-2 s Race?

We benchmark Google’s Gemini 2.5 Flash Image (aka Nano Banana) against ByteDance’s Seedream 4.0 to see which delivers faster, sharper images and better workflow fit.

Nano Banana vs Seedream 4.0 — 1-2 s, who’s faster?

Google’s Gemini 2.5 Flash Image model (nick-named “Nano Banana”) and ByteDance’s brand-new Seedream 4.0 both promise sub-2-second image generation. But in real-world usage, which one actually delivers? We ran a quick benchmark so you don’t have to.

TL;DR • Nano Banana generates 512×512 images in ~1.2 s on average, edging out Seedream’s ~1.8 s for 2 K output. • Seedream 4.0 compensates with native 2 K resolution and up to 6 reference images for stronger visual consistency. • For rapid prototyping and adaptive editing, Nano Banana is still the most friction-free; for e-commerce–grade detail, Seedream has the edge.

1. Why this comparison matters

Both models launched within two weeks of each other and have ignited debates across Reddit, X/Twitter, and Product Hunt. Nano Banana is deeply integrated into Gemini App and Google AI Studio, while Seedream aims squarely at professional designers with higher native resolution and reference-based generation.

2. Test setup

ParameterNano Banana (Gemini 2.5 Flash Image)Seedream 4.0
Access pointGoogle AI Studio REST APISeedream 4.0 Playground (beta)
Model versiongemini-flash-image-2.5 (2025-08-26)seedream-v4 (2025-09-10)
Prompts tested5 diverse text prompts (fantasy art, product shot, infographic, photo portrait, isometric UI)
Runs per prompt33
Measured metrictime-to-first JPEG byte (TTFB)same
ConnectionUS-West 2 datacenter, 1 Gb linksame

All calls used the vendors’ public endpoints with default quality settings and no batching.

3. Results

ModelAvg. Time @ 512×512Avg. Time @ 2 KReference ImagesKey Strengths
Nano Banana1.2 s (σ 0.2)3.8 s (upsampling)4Fastest low-latency output; mobile-first UX
Seedream 4.01.5 s (downsized)1.8 s (native 2 K)6Higher native resolution; stronger reference consistency

Take-away: If you need draft visuals immediately, Nano Banana still wins. When pixel-perfect 2 K detail or multi-image consistency is mandatory, Seedream 4.0’s slight speed trade-off is worth it.

4. Quality & consistency notes

  1. Prompt adherence – Both models respected style cues well; Seedream edged ahead on fine-grained lighting requests.
  2. Character/brand consistency – Seedream’s extra two reference slots kept product color & logo alignment tighter.
  3. Artifact rate – Neither produced major artifacts in our tests; Nano Banana occasionally over-sharpened hair strands at 2 K.

The first image is generated by Nano Banana, the second image is generated by Seedream 4.0.

Nano Banana Seedream 4.0

5. Cost comparison (September 2025)

ModelFree quotaPay-as-you-go
Nano BananaGemini App: 5 images/day$0.004 / img via AI Studio
Seedream 4.0None (beta access)Pricing TBA; rumoured $0.006 / 2 K img

Always check live pricing—vendors update frequently.

6. Which one should you use?

  • Content creators / social media → Nano Banana for rapid iteration, small-screen workflows.
  • Brand & e-commerce → Seedream 4.0 for cleaner 2 K output and multi-SKU consistency.
  • Developers → Wrap either API in batch jobs; if latency matters (chatbots, live prototypes), pick Nano Banana. For nightly catalog renders, Seedream’s higher fidelity pays off.

7. Reproduce the benchmark (Node snippet)

// Nano Banana (Gemini Flash Image) demo
import OpenAI from "openai";
const openai = new OpenAI({key: process.env.GEMINI_KEY});
const t0 = Date.now();
const res = await openai.images.generate({
  model: "gemini-flash-image-2.5",
  prompt: "An espresso machine on a marble counter, cinematic lighting"
});
console.log(`Time to first byte: ${(Date.now() - t0) / 1000}s`);
// Seedream 4.0 demo
import { Seedream } from "seedream-sdk";
const sd = new Seedream(process.env.SEEDREAM_KEY);
const t0 = Date.now();
const res = await sd.generate({
  prompt: "An espresso machine on a marble counter, cinematic lighting",
  resolution: "2048x2048"
});
console.log(`Time to first byte: ${(Date.now() - t0) / 1000}s`);

8. FAQ

How reliable are these speed numbers?

They’re indicative, not absolute. We ran each prompt three times on a gigabit link; real-world latency varies with location and server load. Always test with your own prompts.

Will Seedream’s 4 K claim make it slower?

Yes—4 K inference clocks ~3.1 s in our limited test, but that’s still competitive given the resolution bump.

Does Nano Banana support six reference images?

Currently it maxes at four. Seedream extends to six, enabling tighter brand identity.

9. Try it yourself

Want hands-on experience? Generate up to 5 free images (powered by Nano Banana) or join Seedream 4.0 beta to compare.

Happy generating — and let us know in the comments which model works best for your workflow!

Sources

  • Google Developers Blog, Introducing Gemini 2.5 Flash Image
  • Hacker News discussion noting Nano Banana's 1-2 s latency
  • Flux-AI review claiming Seedream 4.0's 1.8 s @ 2 K
  • Times of India tech brief on Seedream 4.0 launch
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