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Black Forest LabsPrompt guide

FLUX.2 [flex] Prompt Guide

How to write FLUX.2 [flex] prompts: a structure that works, 3 example prompts for text to image, and the settings that change the result. Copy any prompt into the Studio to try it.

Example prompts
3
1 task
Size
4 MP
1 MP · 2 MP · 3 MP · 4 MP
Aspect ratios
9
1:1 · 4:3 · 3:4 · 16:9
Per try from
$0.044/image
1 MP
Try in Studio Call the API

Structure

A FLUX.2 [flex] prompt, piece by piece

Write in this order and keep each part concrete. Physical detail works better than mood words.

  1. 01

    Subject

    The main subject and its key details: material, colour, expression, product features.

  2. 02

    Composition

    Framing and angle: close-up, flat lay, three-quarter view, rule of thirds, negative space.

  3. 03

    Setting and light

    Background, environment and lighting: studio softbox, golden hour, neon.

  4. 04

    Style

    Photo, illustration, 3D render or painting — plus lens or medium details.

Examples

FLUX.2 [flex] prompt examples

Prompts written for this model, grouped by task. Open one in the Studio, then change one part at a time.

  • Text to Image2:3
    Vintage travel poster for “KYOTO”, Mt. Fuji at dawn, bold serif lettering, screen-print texture
    Try in Studio
  • Text to Image1:1
    Packaging mockup of a tea tin labeled “MORNING MIST — Green Tea”, studio photo
    Try in Studio
  • Text to Image
    Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain
    Try in Studio

By task

Prompting each FLUX.2 [flex] task

Text to Image

Lead with the subject, then composition, setting, light and style. Quote any text that must appear in the image.

Settings

Settings that change the result

Set these next to the prompt — in the Studio or as API parameters.

FLUX.2 [flex] generation settings
SettingOptionsEffect
Aspect ratio
aspect_ratio
1:1 · 4:3 · 3:4 · 16:9 · 9:16 · 3:2 · 2:3 · 21:9 · 9:21
default 1:1
Output image shape.
Resolution
resolution
1 MP · 2 MP · 3 MP · 4 MP
default 1MP
Output size in megapixels (1 MP ≈ 1024×1024). FLUX.2 is billed per megapixel.
Price: 1 MP $0.044/image · 2 MP $0.088/image · 3 MP $0.132/image · 4 MP $0.176/image
Steps
steps
1–50
default 50
Sampling steps. More steps add detail and take longer (same price).
Guidance
guidance
1.5–10
default 5
How closely the image follows the prompt (1.5–10).
Prompt upsampling
prompt_upsampling
on / off
default false
Let the model expand and rewrite the prompt before generating.
Seed
seed
—Use the same seed and settings to reproduce a result. Leave empty for random.

FAQ

FLUX.2 [flex] prompting questions

There is no separate negative prompt for FLUX.2 [flex]. Say what you want instead of what you don't, and keep unwanted elements out of the description.

Yes — set "seed" to a fixed number and keep the prompt and settings identical. Use the same seed and settings to reproduce a result. Leave empty for random.

Open FLUX.2 [flex] in the Studio and paste any prompt from this page. Each run shows its exact price before you generate, and failed generations are refunded.