Flux Models Explained: Schnell, Dev, Pro, Ultra and Kontext

Flux is the family of image models from Black Forest Labs (BFL), and its naming trips up almost everyone at first. Schnell, dev, pro, 1.1, Ultra, Raw, Kontext: some of these are separate models, some are modes of the same model, and they differ in speed, quality, licence and where you can run them. This guide sorts them out and then covers the handful of settings you actually need to understand to get good results.

The Flux family at a glance

Hosted platforms often rename these in their menus ('Flux Pro 1.1', 'Flux Dev', 'Flux Fast'), and some ship fine-tuned variants of dev under their own labels. When a menu says 'Flux', look for the second word before you judge the result.

Open weights and what the licences mean

Open weights means you can download the model and run it on your own hardware or a rented GPU. It does not mean you can do anything you like with the output.

• schnell is the permissive one. Its licence allows commercial use of the model and its outputs, which is why it appears in so many free tools.
• dev is open for research and personal use, but commercial use requires a licence from BFL or using it through a host that has one. Many hosted platforms are licensed, so check their terms rather than assuming either way.
• pro models are never downloaded. You pay per generation through an API or a platform plan, and the platform’s terms govern your commercial rights to the images.

If you make work for clients, record which Flux model and which platform produced each image, and keep a copy of the terms you relied on. Our guide on keeping a record of AI work gives a simple method.

Ultra and Raw modes

Both belong to FLUX1.1 [pro] and are switched on in the hosted interface or API rather than chosen as separate models.

Ultra raises the output resolution to around four megapixels while keeping generation fast. Use it when the image is going to print, to a large hero banner, or anywhere you would otherwise need an upscaler. It costs more per image on most hosts.

Raw changes the look rather than the size. Standard Flux output is polished: smooth skin, tidy lighting, an 'AI photograph' finish. Raw aims for the feel of a real camera, with less perfection, more natural texture and less idealised composition. It is the setting to try when clients say the images look too clean. Raw and Ultra can be combined.

How Flux reads a prompt

Flux responds well to plain, descriptive English, including long sentences. A few habits that matter more here than in older models:

1. Write sentences, not tag lists. 'A woman in a yellow raincoat waits at a tram stop in heavy rain, lit by a shop window' works better than 'woman, raincoat, tram stop, rain, 8k'.
2. Quote any text you want rendered. Flux is one of the stronger models for legible text. Keep it short and put it in quotation marks.
3. Name the camera and lens if you want a photographic look. 'Shot on a 35 mm lens, shallow depth of field' is understood and steers the result.
4. Skip prompt weights and negative prompts. Syntax such as (word:1.3) comes from other model families and does little here. Describe what you want present instead.
5. Put the most important thing first. Long prompts work, but the subject should still open the sentence.

Settings at a glance

Labels vary between the BFL playground, Replicate, fal, Krea, Freepik and Leonardo, but these controls appear almost everywhere.

Steps and guidance apply only to the open models; the hosted pro models manage them internally. For editing, Kontext has its own small set of controls, covered in our Kontext editing guide.

Try it

Run this on schnell first to check composition, then on FLUX1.1 [pro] with Raw on for the final.

A small independent bookshop at dusk on a narrow cobbled street, warm light spilling from the window onto wet stones, a hand-painted sign above the door that reads "SECOND CHAPTER", a cyclist passing in soft motion blur, shot on a 35 mm lens, overcast evening light, muted teal and amber palette.

Change the sign text to test legibility, then toggle Raw and compare the stone and glass textures. If the scene looks too staged, remove the colour-palette clause and let the model choose.