FLUX Best Practices

Use this skill when generating prompts for any BFL FLUX model to ensure optimal image quality and accurate prompt interpretation.

Extended reference: `AGENTS.md` in this directory is the long-form upstream FLUX guide (vendored from Black Forest Labs). It is supplementary reference material scoped to this skill only — SKILL.md is the loadable entry point and the authority. It does not override or extend the repository-root AGENTS.md / AGENT_GUIDE.md.

When to Use

• Creating prompts for FLUX.2 or FLUX.1 models
• Text-to-image (T2I) generation
• Image-to-image (I2I) editing with FLUX.2 models
• Structured scene generation with JSON
• Typography and text rendering
• Multi-reference style transfer
• Color-accurate brand generations

Quick Reference

Prompt Structure Formula

[Subject] + [Action/Pose] + [Style/Medium] + [Context/Setting] + [Lighting] + [Camera/Technical]

Model Selection

Use Case	Recommended Model	Notes
Fastest generation	FLUX.2 [klein]	4B or 9B, sub-second
Highest quality	FLUX.2 [max]	Best detail, grounding search
Production balanced	FLUX.2 [pro]	Quality + speed
Typography/text	FLUX.2 [flex]	Best text rendering
Local/development	FLUX.2 [dev]	Open weights
Image editing	FLUX.2 [pro/max]	Pass image URL directly to input_image
Inpainting	FLUX.1 Fill	Object removal/completion
Context editing	FLUX.1 Kontext	Older model, prefer FLUX.2

Critical Rules

1. NO negative prompts - FLUX does not support negative prompts; describe what you want
2. Be specific - Vague prompts produce mediocre results
3. Use natural language - Prose/narrative style works best
4. Specify lighting - Lighting has the biggest impact on quality
5. Quote text - Use "quoted text" for typography rendering
6. Hex colors - Use #RRGGBB format with color description

Related

For API integration (endpoints, polling, webhooks), see the bfl-api skill.

Rules Reference

Read individual rule files for detailed guidance:

• rules/core-principles.md - Universal FLUX prompting principles
• rules/flux2-models.md - FLUX.2 family: klein, max, pro, flex, dev
• rules/flux1-models.md - FLUX.1 family: older generation of FLUX.2 models - pro, Kontext, Fill
• rules/t2i-prompting.md - Text-to-image prompting patterns
• rules/i2i-prompting.md - Image-to-image editing with FLUX.2
• rules/json-structured-prompting.md - Complex scene composition
• rules/hex-color-prompting.md - Precise color specification
• rules/typography-text.md - Text rendering and typography
• rules/multi-reference-editing.md - Multi-image references
• rules/negative-prompt-alternatives.md - Positive alternatives
• rules/model-selection-guide.md - Choosing the right model

Example Prompt

A weathered fisherman in his 70s with deep wrinkles and a salt-and-pepper beard,
wearing a navy cable-knit sweater, standing at the helm of his wooden boat.
Golden hour sunlight from the left creates dramatic rim lighting on his profile.
Shot on Hasselblad with 85mm lens at f/2.8, shallow depth of field with harbor
lights creating soft bokeh in the background. Kodak Portra 400 color science.