What is CFG Scale?
CFG Scale (Classifier-Free Guidance Scale), also called Guidance Scale, is a parameter that controls how strictly the AI follows your text prompt during image generation. It essentially determines the balance between creativity and prompt adherence.
How CFG Scale Works
The Technical Concept
During image generation, the AI considers:
- Conditioned output: What the model generates based on your prompt
- Unconditioned output: What it would generate without guidance
CFG Scale determines how much to emphasize the conditioned (prompted) output over the unconditioned one.
The Formula
Simplified: Final = Unconditioned + CFG × (Conditioned - Unconditioned)
Higher CFG = More influence from your prompt
CFG Scale Values
Low CFG (1-5)
Characteristics:
- More creative/random outputs
- Softer, dreamier images
- Loose prompt interpretation
- More varied results
- Can appear unfocused
Best for: Abstract art, experimental work, soft aesthetics
Medium CFG (6-10)
Characteristics:
- Balanced creativity and adherence
- Natural-looking results
- Good prompt following
- Most commonly used range
Best for: Most general use cases, recommended starting point
High CFG (11-20)
Characteristics:
- Strict prompt adherence
- More contrast and saturation
- Can appear harsh or artificial
- Less creative variation
Best for: Specific requirements, technical accuracy
Very High CFG (20+)
Characteristics:
- Extreme prompt adherence
- Often produces artifacts
- Oversaturated colors
- Distorted details
Generally not recommended
Visual Examples
| CFG Value | Prompt Adherence | Image Quality | Creativity |
|---|---|---|---|
| 3 | Low | Soft/Dreamy | High |
| 7 | Medium | Balanced | Medium |
| 12 | High | Sharp/Contrasty | Low |
| 20 | Very High | Often Artifacted | Very Low |
Recommended Settings by Use Case
Photorealistic Images
- CFG 5-8
- Natural, believable results
- Avoids artificial look
Artistic/Stylized Work
- CFG 7-10
- Good style adherence
- Maintains artistic coherence
Specific Subject Accuracy
- CFG 8-12
- When exact prompt matching matters
- Technical illustrations
Abstract/Creative
- CFG 3-6
- More randomness desired
- Experimental work
CFG Scale + Other Parameters
Interaction with Steps
- Higher CFG often benefits from more steps
- Low steps + high CFG = artifacts
- Balance both parameters together
Interaction with Sampler
- Different samplers respond differently to CFG
- Some samplers prefer lower CFG
- Experiment with combinations
Model-Specific Preferences
- Different models have optimal CFG ranges
- Flux models: Often 3-7
- Stable Diffusion: Often 7-11
- Check model documentation
Troubleshooting with CFG
Images Too Soft/Unfocused
- Increase CFG (try +2-3)
- Add more specific prompt details
- Increase step count
Images Too Harsh/Artificial
- Decrease CFG (try -2-3)
- Use softer prompt language
- Try different sampler
Artifacts and Distortions
- CFG likely too high
- Reduce to 7-10 range
- Increase steps
Prompt Being Ignored
- CFG might be too low
- Increase to 7-10 range
- Check prompt formatting
CFG Scale in Different Platforms
Naming Variations
The same concept has different names:
- CFG Scale - Stable Diffusion
- Guidance Scale - General term
- Guidance - Some platforms
- Prompt Guidance - User-friendly term
Default Values
Common defaults across platforms:
- Stable Diffusion: 7-7.5
- DALL-E: Not user-adjustable
- Midjourney: Stylize parameter (related concept)
Pro Tips
Finding Your Sweet Spot
- Start with default (usually 7)
- Generate test images
- Adjust by 2 points up or down
- Compare results
- Note what works for your style
Style-Specific Recommendations
- Portraits: 6-8 for natural look
- Landscapes: 7-9 for detail
- Anime: 7-10 for style adherence
- Abstract: 3-6 for creativity
Batch Generation Strategy
- Generate same prompt at different CFG values
- Compare results side by side
- Identify optimal range for your use case
Common Misconceptions
"Higher is Better"
False - Higher CFG doesn't mean better images. It means stricter adherence, which often produces worse-looking results.
"One Size Fits All"
False - Optimal CFG varies by model, prompt, and desired output style.
"CFG Adds Details"
Partially false - CFG affects prompt adherence, not detail level. Detail is affected by resolution, steps, and model.
Summary
CFG Scale is a fundamental parameter in AI image generation:
- Low (1-5): Creative, soft, loose interpretation
- Medium (6-10): Balanced, recommended for most use
- High (11-15): Strict adherence, potentially harsh
- Very High (16+): Usually causes artifacts
Start with the default, then adjust based on your specific needs and the model you're using.