gemini-3.1-flash-image is deprecated: move to Nano Banana 2.1

Google deprecated gemini-3.1-flash-image (Nano Banana 2) on October 6, 2026 and tells developers to migrate to gemini-nano-banana-2.1. The deprecations page shows "No shutdown date announced", so nothing stops working today. New code should use the new id, and old code should move before Google names a date.

What the Nano Banana rows say today

These are the rows Google lists for the Nano Banana family on the day this was read. Google notes that a listed shutdown date is the earliest possible date, and that it will give notice before an exact one.

What to change in your code

The swap is one string, but three details differ from Nano Banana 2.

• Model id: use gemini-nano-banana-2.1. There is no gemini-3.1 prefix on the new id.
• Resolution: Google's image guide says the 512px (0.5K) tier is supported on Gemini 3.1 Flash Image but not on Nano Banana 2.1. Draft renders at 512px need 1K instead.
• Price: output image tokens drop from $60 to $30 per 1M, while input rises from $0.50 to $1.50 per 1M. See the linked price post for the per-image numbers.
• Resolution letters: Google requires an uppercase K, such as 1K, 2K or 4K.

What Sume does with the old name

Sume's Image API docs say Nano Banana 2 is retired there: google/nano-banana-2 and nano-banana-2 still work, run as Nano Banana 2.1, and the job stores the 2.1 id. The catalog no longer lists the retired id. Pin google/nano-banana-2.1 in new code and read GET /v1/images/models to confirm what your key can call.

Sume has its own price list, so a Sume image costs more than the same image bought from Google directly. Read the live figure from the endpoint list.