Flux 3 Klein vs Krea 3 for Architecture

Shaun McCallum

November 10, 2026

Flux 3 Klein for fast box edits up to 4K, Krea 3 for edits that bring in a reference image. Both are in Studio now.

Summarize with AI

Flux 3 Klein and Krea 3 are both in Fenestra now. Use Flux 3 Klein for quick, low-cost renders and Regional Edits that change one part of a view. Use Krea 3 when an edit brings in a reference, like a sofa from a product shot, and the rest of the room has to stay put.

Two-storey house with a pale brick ground floor and a light oak upper storey on an overcast day

The same house with the upper storey re-clad in charred black timber, the brick, trees and path unchanged

One Regional Edit box in Flux 3 Klein. The upper storey goes from oak to charred timber; the brick, trees, path and sky stay where they were.

What is Flux 3 Klein?

Flux 3 Klein is the small, fast model in Black Forest Labs' FLUX 3 family, released on 15 October 2026. It has FLUX 3's native 4K and box-level editing in a 5.6-billion-parameter model, and in Fenestra it's in Create, Edit and Regional Edit.

In our tests most Klein generations took under ten seconds, and it's one of the lowest-cost models we offer. That makes it the model for early rounds, when you want ten options on the table before you pick one.

Regional Edit is where it stands out. Draw a box, say what goes in it, and Klein leaves the rest of the view alone: at 2K, everything outside our box stayed within a pixel of the original. This was the whole edit:

box	change
Upper storey	the same upper storey clad in charred black timber boards, windows unchanged

Klein is weaker at composing a room from a board of reference pieces. For that, we'd use Flux 3 or Nano Banana 2.1.

More on Klein, with prompts and specs: Flux 3 Klein for architecture and interior design.

What is Krea 3?

Krea 3 is Krea's image editing model, released on 15 October 2026 and built to change only what you ask for. In Fenestra it's in Edit and Edit Area at 1K or 2K, with Medium, High and Ultra quality.

We gave it a render of a warehouse kitchen and a product shot of a sofa, and asked it to replace only the sofa.

Warehouse kitchen and dining room with oak trusses, a green tiled island, a terracotta floor and a grey sofa — Render

Studio product shot of a deep olive green corduroy sofa on a thin oak plinth — Reference

The room, and the sofa we wanted in it.

Warehouse kitchen with a grey sofa by the windows

The same kitchen with the olive corduroy sofa from the product shot in place of the grey one

Krea 3 swapped the sofa and kept the floor, the island, the table and the light as they were.

Then we asked it to change only the floor, to wide oak boards.

Warehouse kitchen with a terracotta tile floor and an olive sofa

The same kitchen with a wide oak plank floor, the furniture and island unchanged

Terracotta to oak. The sofa, the island and the table didn't move.

Krea's own prompt advice is worth following: start with what stays, then the change, say what each image is for, and use "only" when the edit should touch one thing.

Krea 3 takes longer than Klein, because it reasons about the edit before it renders. It also uses more credits, and more again with reference images.

More on Krea 3, with prompts and specs: Krea 3 for architecture and interior design.

Flux 3 Klein vs Krea 3: which should you use?

	Flux 3 Klein	Krea 3
Made by	Black Forest Labs	Krea
Best for	Quick options, Regional Edit boxes, 4K	Swapping in a reference, changing one thing
In Fenestra	Create, Edit, Regional Edit	Edit, Edit Area
Resolution	1K, 2K, 4K	1K, 2K
Reference images	Use Flux 3 or Nano Banana 2.1 instead	Up to seven; say what each is for
Speed	Seconds	Longer: it reasons about the edit first
Credits	One of our lowest	More, and more again with references

Start a design round in Flux 3 Klein. Switch to Krea 3 when the change comes from a reference image, or when one piece has to change and nothing else.

How do you use Flux 3 Klein and Krea 3 in Fenestra?

Open a project in Studio and choose Edit.
Pick Flux 3 Klein or Krea 3 Edit from the model list. Both are marked New.
For Klein, switch to Regional Edit and draw a box over each part to change. For Krea, add your reference images and say what each one is for.
Choose the resolution and press Edit.

Try Flux 3 Klein and Krea 3

Open Fenestra

Frequently asked questions

Flux 3 Klein is the small, fast model in Black Forest Labs' FLUX 3 family, released on 15 October 2026. In Fenestra it creates and edits at 1K, 2K or 4K, in Create, Edit and Regional Edit.

Krea 3 is Krea's image editing model, released on 15 October 2026 and built to change only what you ask for. In Fenestra it edits at 1K or 2K, in Edit and Edit Area.

They suit different jobs. Flux 3 Klein is faster, uses fewer credits, and handles Regional Edit boxes and 4K. Krea 3 is the one for edits that bring in a reference image, like a sofa from a product shot, while the rest of the room stays as it was.

Its weights are open under the FLUX Kommunity License, which allows free commercial use for individuals and companies with under $5M annual revenue. In Fenestra it runs in the cloud, so you don't need the weights or a GPU.

In Fenestra, open Studio, choose Edit or Edit Area and pick Krea 3 Edit. Start the prompt with what should stay, then the change, and say what each reference image is for.

AI Kitchen Design With ChatGPT and Fenestra

Photograph a client's kitchen once, then try new worktops, cabinets and lighting in ChatGPT and Fenestra. The walls, windows and layout stay as they are.

Shaun McCallumNov 3, 2026