Nano Banana 2.1 vs Nano Banana 2: What Actually Changed

What Google says improved in 2.1

Google's model page describes Nano Banana 2.1 as an update that keeps Nano Banana 2's Flash-level speed and cost while improving four things. Its list of key updates adds two concrete changes on top.

Nano Banana 2.1 vs Nano Banana 2: specs side by side

Tokens and prices are listed as 512px · 1K · 2K · 4K. Output tokens don't change with aspect ratio. Google Cloud's model page lists a higher 4K token count for 2.1 (3,780) than the Gemini API docs (2,520) — check the usage figures on a real 4K call before you budget at that size.

What did not change — and what people get wrong

• Search grounding is not new. Nano Banana 2 already supported grounding with Google Web Search and Image Search. 2.1 keeps the same options and the same limit: Image Search grounding can't use real-world images of people.
• 4K is not new. Both models output up to 4K, and both use the same output token counts at 1K, 2K and 4K.
• The reference-image limit is the same. Up to 14 images per request, with up to 4 of them used for character consistency.
• The aspect ratios are the same. The same 14 ratios, from 1:8 to 8:1. 2.1 just renders the extreme ones cleanly at 2K and 4K.
• Watermarking is the same. Every image from either model carries Google's invisible SynthID watermark.

The one thing 2.1 removed: 512px output

Nano Banana 2 offers a 512px size (the API value is "512") aimed at low-latency drafts and heavy pipelines. Nano Banana 2.1 does not support it — output starts at 1K.

If you used 512px to keep costs down, look at Nano Banana 2 Lite (gemini-3.1-flash-lite-image): Google's pricing page lists it at $0.0336 per 1K image, already below Nano Banana 2's $0.045 at 512px. If you need small images from 2.1 itself, generate at 1K and downscale on your side.

Should you switch from Nano Banana 2 to 2.1?

Migrating from Nano Banana 2 to 2.1: API checklist

1. Change the model ID. gemini-3.1-flash-image → gemini-nano-banana-2.1. The request shape, the aspect ratios and the 1K / 2K / 4K size values stay the same.
2. Remove 512px requests. An image_size of "512" isn't supported on 2.1. Use "1K" and downscale if you need small files.
3. Drop sampling parameters. Google Cloud's model page says 2.1 returns an error if you set seed, temperature, topP, topK or logprobs.
4. Set the thinking level explicitly. 2.1 defaults to medium, where Nano Banana 2 defaulted to minimal. More thinking adds latency and thinking tokens; the interim "thought images" themselves aren't charged.
5. Re-run your prompt regression set. Focus on prompts with quoted text, infographics and multi-turn edit chains — that is where Google says 2.1 changed.
6. On Google Cloud, use the global endpoint. Google Cloud's model page lists 2.1 in the global region only, while Nano Banana 2 also runs in the US and EU multi-regions.

{
  "model": "gemini-nano-banana-2.1",
  "input": "Your prompt",
  "response_format": { "type": "image", "aspect_ratio": "16:9", "image_size": "2K" },
  "generation_config": { "thinking_level": "minimal" }
}

Full curl, Python and JavaScript examples are in the Nano Banana 2.1 API guide.

Test the difference yourself

Run these on both models. Each one leans on a specific change in 2.1.

More prompts, by use case, in the Nano Banana 2.1 prompt guide.

FAQ

Sources

1. Gemini API — Gemini Nano Banana 2.1 model page
2. Gemini API — Gemini 3.1 Flash Image (Nano Banana 2) model page
3. Gemini API — Nano Banana image generation guide
4. Gemini API — Pricing
5. Gemini API — Deprecations
6. Google Cloud — Gemini Nano Banana 2.1

Google updates these pages without notice. If anything here disagrees with them, Google's page is right.