AI Image Editing Model
Black Forest Labs' distilled 9 billion parameter image generation model with sub-second inference and multi-reference support
![FLUX.2 [klein] 9B generated image of A high-end cinematic close-up of a vintage 1950s camera lens reflecting a sun...](https://assets.lumenfall.ai/IM3VUset8xNz4_evHSf-EAqKuEgzsoI9Nn-DN1WmIZ8/rs:fill:400:400:1/plain/gs://lumenfall-prod-assets/z89mwfn35gzu0t4suxdnrn2korop@jpeg)
![FLUX.2 [klein] 9B generated image of A hyper-realistic close-up of a weathered, vintage leather traveler's journal...](https://assets.lumenfall.ai/XDR-FXfDTC7CgqpnMdUAHwnNMwelAGvoP7uZSg9CGpY/rs:fill:400:400:1/plain/gs://lumenfall-prod-assets/9otlhkaizlrav8xejgv4qnn4kicw@jpeg)
flux.2-klein-9b
Starting from
Prices shown are in USD · Some prices estimated from per-megapixel or per-token pricing
See all providersFastest generation through fal at 936ms median latency with 100.0% success rate.
Aggregated from real API requests over the last 30 days.
| # | Provider | p50 Gen Time | p95 Gen Time | Success Rate | TTFB (p50) |
|---|---|---|---|---|---|
| 1 | fal | 936ms | 1,870ms | 100.0% | 887ms |
FLUX.2 [klein] 9B is available from 2 providers, with per-image pricing starting at $0.006 through fal.ai.
fal/flux.2-klein-9b
replicate/flux.2-klein-9b
https://api.lumenfall.ai/openai/v1
flux.2-klein-9b
curl -X POST \ https://api.lumenfall.ai/openai/v1/images/generations \ -H "Authorization: Bearer $LUMENFALL_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "flux.2-klein-9b", "prompt": "", "size": "1024x1024" }'# Response:# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }import OpenAI from 'openai';const client = new OpenAI({ apiKey: 'YOUR_API_KEY', baseURL: 'https://api.lumenfall.ai/openai/v1'});const response = await client.images.generate({ model: 'flux.2-klein-9b', prompt: '', size: '1024x1024'});// { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }console.log(response.data[0].url);from openai import OpenAIclient = OpenAI( api_key="YOUR_API_KEY", base_url="https://api.lumenfall.ai/openai/v1")response = client.images.generate( model="flux.2-klein-9b", prompt="", size="1024x1024")# { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }print(response.data[0].url)| Parameter | Type | Description | Modes |
|---|---|---|---|
prompt
|
string | Required. Text prompt for image generation |
T2I
Edit
|
seed
|
integer | Random seed for reproducibility |
T2I
Edit
|
| Parameter | Type | Description | Modes |
|---|---|---|---|
size
|
string |
Image dimensions as WxH pixels (e.g. "1024x1024") or aspect ratio (e.g. "16:9")
WxH determines both shape and scale (aspect_ratio and resolution are ignored when size is provided). W:H format is equivalent to aspect_ratio.
|
T2I
Edit
|
aspect_ratio
|
string |
Aspect ratio of the output image (e.g. "16:9", "1:1")
Controls shape independently of scale. Use with resolution to control both. If size is also provided, size takes precedence. Any ratio is accepted and mapped to the nearest supported value.
|
T2I
Edit
|
resolution
|
string |
Output resolution tier (e.g. "1K", "4K")
auto
1K
Controls scale independently of shape. Higher tiers produce larger images and cost more. If size is also provided, size takes precedence for scale. Any tier is accepted and mapped to the nearest supported value.
|
T2I
Edit
|
| Output |
size
|
aspect_ratio
+
resolution
|
|
|---|---|---|---|
| Flexible | |||
| Auto | "auto" |
— | Model chooses optimal dimensions |
|
Custom
1–14142px per side
|
"WxH" |
— | Any pixel dimensions within model constraints |
| Output |
size
|
aspect_ratio
+
resolution
|
|
|---|---|---|---|
| 1183 × 887 | "1183x887" |
or |
"4:3"
+
"1K"
|
| 916 × 1145 | "916x1145" |
or |
"4:5"
+
"1K"
|
| 1145 × 916 | "1145x916" |
or |
"5:4"
+
"1K"
|
| 1024 × 1024 | "1024x1024" |
or |
"1:1"
+
"1K"
|
| 887 × 1182 | "887x1182" |
or |
"3:4"
+
"1K"
|
| 836 × 1254 | "836x1254" |
or |
"2:3"
+
"1K"
|
| 1254 × 836 | "1254x836" |
or |
"3:2"
+
"1K"
|
| 768 × 1365 | "768x1365" |
or |
"9:16"
+
"1K"
|
| 1365 × 768 | "1365x768" |
or |
"16:9"
+
"1K"
|
| 670 × 1564 | "670x1564" |
or |
"9:21"
+
"1K"
|
| 1563 × 670 | "1563x670" |
or |
"21:9"
+
"1K"
|
size
Exact pixel dimensions
"1920x1080"
aspect_ratio
Shape only, default scale
"16:9"
resolution
Scale tier, preserves shape
"1K"
size is most specific and always wins. aspect_ratio and resolution control shape and scale independently.
7:1 on a model with
4:1 and 8:1,
you get 8:1.
0.5K 1K 2K 4K)
or megapixel tiers (0.25 1).
If the exact tier isn't available, you get the nearest one.
| Parameter | Type | Description | Modes |
|---|
| Parameter | Type | Description | Modes |
|---|---|---|---|
response_format
|
string |
How to return the image
url
b64_json
Default:
"url" |
T2I
Edit
|
output_format
|
string |
Output image format
png
jpeg
gif
webp
avif
Gateway converts to requested format if provider doesn't support it natively.
|
T2I
Edit
|
output_compression
|
integer | Compression level for lossy formats (JPEG, WebP, AVIF) |
T2I
Edit
|
n
|
integer |
Number of images to generate
Default:
1Gateway generates multiple images in parallel even if provider only supports 1.
|
T2I
Edit
|
Provider-specific passthrough fields, available only when the request is routed to the listed provider.
| Parameter | Type | Description | Modes |
|---|---|---|---|
|
fal
|
|||
enable_safety_checker
|
boolean | If set to true, the safety checker will be enabled. |
T2I
Edit
|
num_inference_steps
|
integer | The number of inference steps to perform. |
T2I
Edit
|
sync_mode
|
boolean | If `True`, the media will be returned as a data URI. Output is not stored when this is True. |
T2I
Edit
|
|
replicate
|
|||
disable_safety_checker
|
boolean | Disable safety checker for generated images. |
T2I
Edit
|
go_fast
|
boolean | Run faster predictions with additional optimizations. |
T2I
Edit
|
megapixels
|
string |
Resolution in megapixels
0.25
0.5
1
2
4
|
T2I
Edit
|
output_quality
|
integer | Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs. |
T2I
Edit
|
How we handle parameters across different providers
Not every provider speaks the same language. When you send a parameter, we handle it in one of four ways depending on what the model supports:
| Behavior | What happens | Example |
|---|---|---|
passthrough |
Sent as-is to the provider | style, quality |
renamed |
Same value, mapped to the field name the provider expects | prompt |
converted |
Transformed to the provider's native format | size |
emulated |
Works even if the provider has no concept of it | n, response_format |
Parameters we don't recognize pass straight through to the upstream API, so provider-specific options still work.
FLUX.2 [klein] 9B is ranked #30 in Text-to-Image with an Elo of 1207 and #12 in Image Editing with an Elo of 1206 on the Lumenfall Arena, where real users pick the better image in blind comparisons. These rankings are based on 2 blind-vote competitions.
1 model without pricing omitted.
26 models waiting for enough speed data.
“Ad for 'Magic Burger'. Dynamic, exploded burger with all components (bun, patty, cheese, lettuce, tomato, sauce) suspended in mid-air. Emphasize photorealistic detail and a sense of motion. Dark, fiery background with glowing embers. Integrate text: 'MAGIC BURGER' as a prominent title, 'LIMITED TIME ONLY' as a secondary message, and '€6.99' in a starburst, all rendered with a fiery, glowing effect.”
“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”
“Ad for 'Magic Burger'. Dynamic, exploded burger with all components (bun, patty, cheese, lettuce, tomato, sauce) suspended in mid-air. Emphasize photorealistic detail and a sense of motion. Dark, fiery background with glowing embers. Integrate text: 'MAGIC BURGER' as a prominent title, 'LIMITED TIME ONLY' as a secondary message, and '€6.99' in a starburst, all rendered with a fiery, glowing effect.”
“Handwritten-style chalkboard menu in a cozy café, all text rendered in the exact same realistic chalk handwriting style with natural variations in letter size, slight slant, and chalk texture — no printed or digital fonts anywhere on the board. Title at the top in elegant cursive chalk handwriting: ‘TODAY’S SPECIALS – APRIL 30, 2026’. Below it, three menu items also in the same handwritten chalk style: ‘Truffle Mushroom Risotto – $24’, ‘Grilled Octopus with Lemon & Herbs – $28’, ‘Brown Butter Chocolate Chip Cookies – $9’. At the very bottom, smaller text in the identical handwritten chalk style (slightly smaller but still clearly legible with the same handwriting characteristics): ‘All items made fresh daily • Ask about our gluten-free options’. Warm ambient café lighting, visible chalk dust and smudges, realistic handwriting imperfections, no clean printed text anywhere.”
“Ad for 'Magic Burger'. Dynamic, exploded burger with all components (bun, patty, cheese, lettuce, tomato, sauce) suspended in mid-air. Emphasize photorealistic detail and a sense of motion. Dark, fiery background with glowing embers. Integrate text: 'MAGIC BURGER' as a prominent title, 'LIMITED TIME ONLY' as a secondary message, and '€6.99' in a starburst, all rendered with a fiery, glowing effect.”
See how FLUX.2 [klein] 9B performs head-to-head against other AI models, ranked by community votes in blind comparisons.
FLUX.2 [klein] 9B starts at $0.006 per image through Lumenfall. Pricing varies by provider. Lumenfall does not add any markup to provider pricing.
You can use FLUX.2 [klein] 9B through Lumenfall's OpenAI-compatible API. Send requests to the unified endpoint with model ID "flux.2-klein-9b". Code examples are available in Python, JavaScript, and cURL.
FLUX.2 [klein] 9B is available through Replicate and fal.ai on Lumenfall. Lumenfall automatically routes requests to the best available provider.
FLUX.2 [klein] 9B supports images up to 2048x2048 resolution.
Generate images with custom prompts — no API key needed.
![FLUX.2 [klein] 9B — Photorealism](https://assets.lumenfall.ai/59jX1UNnt3DffY3w44DgoxUuHK0Y9ps4KYZXU4NXNOo/rs:fill:400:300:1/plain/gs://lumenfall-prod-assets/9iyyim6zz3h95bhky1h4tbl2gvsx@jpeg)
![FLUX.2 [klein] 9B — Text Rendering](https://assets.lumenfall.ai/p_Z4YTdE6bkvec6rWHG059Ciq1qBh2kIfs8e21qEFmM/rs:fill:400:300:1/plain/gs://lumenfall-prod-assets/d3oncfxm7iebaynmda4br025isgw@jpeg)