ComfyUI Node
arkennemasis fal · Flux 2 Klein 4B · $0.005/MP
Text-to-image generation with FLUX.2 [klein] 4B from Black Forest Labs. Enhanced realism, crisper text generation, and native editing capabilities. Pricing (from fal, 2026-09-29): $0.005 per megapixel (fal's billing unit). Model page: https://fal.ai/models/fal-ai/flux-2/klein/4b Key: FAL_KEY in the .env next to run_nvidia_gpu.bat. Results are saved in output/fal/fal-ai_flux-2_klein_4b/.
arkennemasis fal · Flux 2 Klein 4B · $0.005/MP
- images
- image_paths
- timings
- has_nsfw_concepts
- seed
- prompt
- info
◄prompt►
◄seed-1►
◄num_inference_steps4►
◄image_sizelandscape_4_3►
◄image_size_width1024►
◄image_size_height1024►
◄num_images1►
◄enable_safety_checkertrue►
◄output_formatpng►
◄max_cost_usd20.0►
◄reuse_identical_runtrue►
◄extra_json►
◄max_concurrent1►
Categoryarkennemasis/fal/Image/Flux
Inputs (13)
| Name | Type | Default | Description |
|---|---|---|---|
| prompt | STRING | The prompt to generate an image from. | |
| seed | INT | -1-1–2147483647 | The seed to use for the generation. If not provided, a random seed will be used. -1 leaves it to the model. |
| num_inference_steps | INT | 44–8 | The number of inference steps to perform. |
| image_size | COMBO | landscape_4_3 | The size of the image to generate. 'custom' uses the width and height below. |
| image_size_width | INT | 102416–14142 | Width in pixels when image_size is 'custom'. |
| image_size_height | INT | 102416–14142 | Height in pixels when image_size is 'custom'. |
| num_images | INT | 11–4 | The number of images to generate. |
| enable_safety_checker | BOOLEAN | true | If set to true, the safety checker will be enabled. Disabling it requires account authorization; unauthorized requests are always checked, and images flagged as unsafe are returned as black images. |
| output_format | COMBO | png | The format of the generated image. |
| max_cost_usdopt | FLOAT | 20.00–100000 | Safety cap. If the estimated cost of this run is above this many US dollars the node stops BEFORE sending anything to fal. 0 = no cap. |
| reuse_identical_runopt | BOOLEAN | true | If these exact inputs (the settings AND the same pictures/clips/audio) were already paid for and the files are still in output/fal, return them instead of paying again - also after a ComfyUI restart. Turn off for a fresh take with the same settings. |
| extra_jsonopt | STRING | Advanced: a JSON object merged into the request last, for any fal field this node has no box for. Example: {"seed": 7}. Leave empty normally. | |
| max_concurrentopt | INT | 11–32 | How many paid fal calls may run at the same time in one run, across every fal node. 1 (default) = one after another. This node starts its paid part only while fewer than this many fal calls are running. Once any fal node fails, the ones still waiting are not started, so nothing more is billed. |
Outputs (7)
| Name | Type | Description |
|---|---|---|
| images | IMAGE | — |
| image_paths | STRING | — |
| timings | STRING | — |
| has_nsfw_concepts | STRING | — |
| seed | INT | — |
| prompt | STRING | — |
| info | STRING | JSON: request id, cost estimate, saved files and fal's full answer. |