FLUX 3 Prompt Guide: Black Forest Labs' Own Structure, Exact Text and Reference Images, for FLUX 3 Image and Klein, With Examples You Can Run (2026)

Black Forest Labs' advice for FLUX 3 Image is to start short: the model expands a short prompt "into a detailed description before it generates the image", so you write more only where you want control, over positions, light or text. Put exact words in quotation marks and say where they go and how they look; there is no negative prompt and no seed field, so describe what you want and compare a few results. In our tests, FLUX 3 Klein set every word right on a three-line sign and on two ads, while FLUX 3 misspelled a word in the longer ad.

This guide covers the structure, text in the image, reference images and edits, FLUX 3 Image or Klein, what to avoid, and examples you can run.

A note on who wrote this: GenMagic runs FLUX 3 Image and FLUX 3 Image Klein. The quoted advice comes from Black Forest Labs' prompting basics for FLUX 3 Image, read November 10, 2026; the results come from our own tests, linked where used. Every FLUX model, its price and licence: FLUX API and is FLUX free?.

Table of contents

1. The structure
2. Text in the image
3. Reference images and edits
4. FLUX 3 Image or Klein
5. What to avoid
6. Examples you can run
7. Questions

The structure

Black Forest Labs offers this as "a useful starting structure, not a strict formula":

[Subject], [location], [style], [camera settings], [lighting], [colors], [effect], [additional elements]

• Use full sentences that say how the elements relate: who is where, facing what.
• "A short prompt works." Most images do not need a long caption; add detail where the model should not decide for you.
• Name things you can see. Black Forest Labs' own example avoids filler like "beautiful", "iconic" and "masterpiece"; every phrase names something visible.
• Iterate fast at a small size, then render the keeper larger (768sq is Black Forest Labs' suggestion for quick tries).

Text in the image

• Exact words in quotation marks, then where they go and how they look: the title "NORTHBOUND COFFEE" in bold condensed capitals across the top.
• Line breaks: write \n inside the quote for a new line.
• Other scripts work the same way, quoted directly.
• Short beats long: in our ad test, FLUX 3 set a short feed ad perfectly but wrote "crualty" and turned "GLOW" on the label into "CLOW" in a story ad with more text; FLUX 3 Klein got both ads right. In our image generator test, both spelled a three-line shop sign correctly.

Every model that set every word right in our tests: images with exact text.

Reference images and edits

• Up to 10 reference images, each at least 256 by 256 pixels and at most 16 megapixels, by Black Forest Labs' docs.
• Refer to them by position: "image 1" is the first you send, "image 2" the second, and say what each is for: "Turn Image 1 in the Style of Image 2".
• One change at a time: Black Forest Labs notes the model keeps the rest of the image the same between edits.
• Product photos: in our ad test, FLUX 3 Klein kept the product and its label as photographed.

FLUX 3 Image or Klein

FLUX 3 Image has no seed field, so the same prompt can come out differently each time; FLUX 3 Image Klein takes a seed, which helps when you want to change one word of a prompt and compare. FLUX 3 Klein's weights are also open for smaller businesses: is FLUX free?

What to avoid

• Negative prompts: there is no negative prompt field; describe what should be there ("an empty street") rather than what should not.
• Subjective filler: "stunning", "8k", "masterpiece" add nothing the model can see.
• Long text in a small space on FLUX 3: split it, or use FLUX 3 Klein, which got the longer ad right in our test.
• Expecting a seed on FLUX 3 Image: compare several results before deciding a prompt change worked.

Examples you can run

Each link opens the GenMagic studio with the model and the prompt ready; you see the price before you generate.

A shop sign with three lines (FLUX 3 Image Klein): "A vintage enamel shop sign mounted on a brick wall, red and cream, reading exactly "MORNING CROWN BAKERY" on the first line, "EST. 1987" on the second line and "SOURDOUGH DAILY" on the third line. Straight-on photo, soft daylight." Open in the studio

A fantasy illustration (FLUX 3 Image): "A lone knight in weathered silver armor stands at the edge of a cliff above a misty valley with a ruined castle, at dawn, painted illustration with visible brushwork, low angle, soft golden backlight, cool blue shadows, a red banner moving in the wind." Open in the studio

A product shot (FLUX 3 Image Klein): "A matte white ceramic coffee mug with a thin gold rim on a light oak table, morning window light from the left, a soft shadow to the right, shallow depth of field, warm neutral colors, clean commercial product photo." Open in the studio

More prompts by what you make: fantasy art, posters, product photos, images in bulk. Every FLUX model and its price: FLUX pay as you go.

Prompt guides for other image models: Nano Banana, GPT Image. For video: Seedance, Veo 3.1, Kling 3.0.

Teaching AI video or images on YouTube, in a course or in n8n templates? The creator program pays 15% in cash of what the people you bring pay in their first month.

Questions

Is there an official FLUX 3 prompt guide? Yes: Black Forest Labs' prompting basics for FLUX 3 Image in its documentation. Its starting structure is subject, location, style, camera settings, lighting, colors, effect and additional elements, in full sentences.

Does FLUX 3 support negative prompts? No: there is no negative prompt field. Describe what you want instead.

How do I get FLUX 3 to write text correctly? Put the exact words in quotation marks, say where they go and how they look, use \n for line breaks, and keep long text short or use FLUX 3 Klein, which set every word right in our ad test.

Does FLUX 3 have a seed? FLUX 3 Image does not, so results vary between runs; FLUX 3 Image Klein takes one.

How many reference images does FLUX 3 take? Up to 10, referred to as "image 1", "image 2" and so on, by Black Forest Labs' docs.