FLUX
Use the bfl-flux-lora integration to create customized styles and characters; combine the power of the Flux engine with LoRA fine-tuning for pinpoint results.
Avg Run Time: 20.000s
Model Slug: bfl-flux-lora
Playground
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Output
Example Result
Preview and download your result.

API & SDK
Create a Prediction
Send a POST request to create a new prediction. This will return a prediction ID that you'll use to check the result. The request should include your model inputs and API key.
Get Prediction Result
Poll the prediction endpoint with the prediction ID until the result is ready. The API uses long-polling, so you'll need to repeatedly check until you receive a success status.
Readme
Overview
bfl-flux-lora refers to LoRA (Low-Rank Adaptation) models trained on the FLUX text-to-image architecture developed by Black Forest Labs (BFL), a company based in Freiburg im Breisgau, Germany. These LoRAs enable fine-tuning of base FLUX models like Flux.1 [dev], Flux.1 [schnell], Flux.2 series (including Pro, Flex, Dev, and open-source Klein), allowing customization for specific styles, subjects, or tasks while leveraging the core model's capabilities in high-quality image generation from text prompts. Key features include efficient adaptation with low parameter counts (e.g., rank-4 to rank-16), support for classifier-free guidance reintroduction for enhanced creativity, and compatibility with quantization for memory efficiency during training and inference.
The underlying architecture of FLUX is based on latent flow matching, incorporating a 12B parameter-scale model with multimodal components, and recent Flux.2 variants integrate Mistral AI's Mistral-3 (24B parameters) vision-language model for improved prompt understanding, photorealism, typography, and image reference handling. What makes bfl-flux-lora unique is its ability to train on resource-intensive FLUX bases with optimizations like 8-bit quantization, SageAttention for faster inference, and specific learning rate schedules (e.g., lower rates for standard LoRA at 1e-5, higher for LoKr at 1e-3), enabling high-fidelity adaptations without full model retraining. Recent developments include Flux.2 releases in November 2025 with open-source elements and tools like Flux.1 Kontext for in-context image generation.
Technical Specifications
- Architecture: Latent flow matching with multimodal blocks, projections, and MLP layers; supports LoRA (standard) and LoKr (lycoris) types
- Parameters: Base FLUX ~12B; LoRA ranks typically 4-16 (e.g., rank-16 trains all components); Flux.2 integrates 24B Mistral-3 VLM
- Resolution: Not explicitly specified; optimized for high-quality outputs with validation inference steps around 20
- Input/Output formats: Text prompts (with optional CFG vectors); image outputs; supports VAE encodes, safetensors, FP16/bf16/8-bit quantization
- Performance metrics: 8-bit quantization enables rank-1 LoRA on 16GB VRAM (~30GB mem in fp16/bf16); SageAttention speeds inference; Flux.2 claims superior prompt following and editing consistency
Key Considerations
- Requires substantial system RAM (~50GB for quantization at startup) plus GPU VRAM; use offloadduringstartup=true for memory issues
- Best practices: Set modeltype=lora, modelfamily=flux; use validationnuminferencesteps=20 for efficiency; enable --fluxfastschedule=true for Schnell variants
- Common pitfalls: High learning rates (e.g., 1e-3 for standard LoRA) can overtrain; avoid gradientaccumulation_steps with bf16 if degrading quality, though recent tests show it's viable
- Quality vs speed trade-offs: Reintroducing CFG (guidance scale 3.5-4.5) boosts creativity/variability but slows inference 20-50% and may increase VRAM 20%; higher steps improve quality but extend time
- Prompt engineering tips: Flux has limited diversity, so fewer steps suffice; leverage base model prompting guides for Flux.2; use regularization data to preserve base capabilities
Tips & Tricks
- Optimal parameter settings: --lorarank=4 for reduced VRAM/size; 8-bit quantization for higher batch sizes without quality loss; learning rates 1e-5 (standard LoRA, AdamW) or 1e-3/2e-4 (LoKr)
- Prompt structuring advice: Follow Flux.2 guides for detailed, style-specific prompts; test CFG vectors to balance adherence vs creativity
- How to achieve specific results: For Schnell LoRAs, add --fluxfastschedule=true; use SageAttention (--attentionmechanism=sageattention) for validation speedups
- Iterative refinement strategies: Train with isregularisationdata for bleed prevention; monitor with lower ranks first, scale up; validate at 20 steps
- Advanced techniques: Batched CFG for 50% slower but creative outputs; combine with Flux tools like Fill/Depth for inpainting/control (Pro/Dev variants)
Capabilities
- Excels in high-fidelity text-to-image generation with strong prompt adherence, photorealism, and typography
- Supports fine-tuned adaptations for custom subjects/styles via low-rank training on dev/schnell bases
- High-quality outputs with editing consistency, world knowledge integration, and faithful style representation in Flux.2
- Versatile for text+image prompting (Kontext), control nets (Canny/Depth), and mixing (Redux)
- Technical strengths: Efficient quantization/training (bf16+int8 matches fp32); fast inference optimizations; stable convergence with multi-dataset support
What Can I Use It For?
- Professional applications: Image editing workflows with inpainting/outpainting (Flux.1 Fill) and control-based generation (Depth/Canny)
- Creative projects: Custom LoRA training for character/subject identity, aesthetics variation, and realism enhancement as in Flux.1 Krea Dev
- Business use cases: Scalable production image generation with improved reference handling and prompt understanding in Flux.2
- Personal projects: Flux LoRA fine-tuning on GitHub tools like SimpleTuner for style-specific datasets
- Industry-specific applications: Typography-focused designs, photorealistic visuals, and in-context editing for media/content creation
Things to Be Aware Of
- Experimental features: Flux.1 Tools (Fill, Depth, Canny, Redux) and Kontext for hybrid text/image prompting; Flux.2 VAE open-sourced
- Known quirks: Dev model is guidance-distilled (straight trajectory); high RAM for startup; limited diversity requires careful step counts
- Performance considerations: OOM risks mitigated by dequantization offload, FP16 LoRA processing; Flux2 workflows optimized for lower VRAM
- Resource requirements: 50GB+ system RAM, 16GB+ VRAM minimum with 8-bit; higher for full rank-16
- Consistency factors: Regularization data preserves base model; Flux.2 enhances editing/prompt fidelity
- Positive user feedback themes: Efficient training matching SD1.5 LoRAs but better on large datasets; quantization enables accessible hardware
- Common concerns: Slower CFG inference; potential overtraining at high LR; Schnell needs manual fast schedule
Limitations
- High memory demands (50GB RAM + significant VRAM) limit accessibility without quantization/offloading
- Limited inherent diversity in base Flux requires CFG tweaks or LoRA for variability; not ideal for highly stochastic outputs
- Training larger datasets favors LoKr over standard LoRA; full fp32 offers no quality edge over bf16+int8
Pricing
Pricing Type: Dynamic
Charge $0.035 per image generation
Pricing Rules
| Parameter | Rule Type | Base Price |
|---|---|---|
| num_images | Per Unit Example: num_images: 1 × $0.035 = $0.035 | $0.035 |
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