FLUX.2 [klein] 4B Image Edit API
Image Edit with FLUX.2 [klein] 4B by Black Forest Labs. The fastest FLUX.2 — open weights, sub-second, a fraction of a cent.
Try FLUX.2 [klein] 4B Image Edit
Up to 4 reference images to edit or combine. Refer to them as "image 1", "image 2"… in the prompt.
Output image shape.
1K ≈ 1 MP; 2K ≈ 4 MP (long side up to 2048 px).
Create a free account with Google or email — pay only for what you generate.
Your image will appear here
Write a prompt, pick your settings and hit Run. You only pay for successful generations.
Also available: FLUX.2 [klein] 4B Text to Image
FLUX.2 [klein] 4B Image Edit API
/api/v1/run/bfl/flux-2-klein-4b/editSubmits an asynchronous job and returns 202 with a generation id. Poll GET /api/v1/generations/{id} or pass webhook_url. See job lifecycle.
Input parameters
| Name | Type | Description | Affects price |
|---|---|---|---|
promptrequired | string | Describe the shot: subject, action, camera movement, lighting and style. | No |
image_urlsrequired | string[] (URLs) | Up to 4 reference images to edit or combine. Refer to them as "image 1", "image 2"… in the prompt. Max items: 4 | No |
aspect_ratio | string (enum) | Output image shape. Values: 1:1 · 4:3 · 3:4 · 16:9 · 9:16 · 3:2 · 2:3 Default: 1:1 | Yes |
resolution | string (enum) | 1K ≈ 1 MP; 2K ≈ 4 MP (long side up to 2048 px). Values: 1K · 2K Default: 1K | Yes |
seed | integer | Use the same seed and settings to reproduce a result. Leave empty for random. | No |
webhook_url | string (URL) | Optional. We POST the finished generation here, signed with your webhook secret. Webhooks | No |
Request
curl -X POST https://cheapergen.com/api/v1/run/bfl/flux-2-klein-4b/edit \
-H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"prompt": "Turn the room in image 1 into a snowy winter cabin; keep the furniture layout",
"image_urls": [
"https://cdn.cheapergen.ai/samples/portrait.jpg"
],
"aspect_ratio": "1:1",
"resolution": "1K"
}'Response
{
"id": "gen_8c2QmX1nq0k4",
"object": "generation",
"model": "bfl/flux-2-klein-4b",
"endpoint": "bfl/flux-2-klein-4b/edit",
"mode": "edit",
"status": "queued",
"input": {
"prompt": "Turn the room in image 1 into a snowy winter cabin; keep the furniture layout",
"image_urls": [
"https://cdn.cheapergen.ai/samples/portrait.jpg"
],
"aspect_ratio": "1:1",
"resolution": "1K"
},
"output": null,
"error": null,
"cost": {
"amount_usd": 0.2255,
"currency": "usd",
"estimated": true,
"official_usd": null,
"saved_usd": null
},
"source": "api",
"started_at": null,
"completed_at": null,
"urls": {
"get": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4",
"cancel": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4/cancel"
},
"created_at": "2026-10-15T09:21:04Z"
}FLUX.2 [klein] 4B pricing
Pay per image. No subscription. Failed generations are refunded automatically.
| Tier | Official price | Cheaper Gen. | You save |
|---|---|---|---|
1K ≈1 MP | $0.0007/img | −95% | |
2K ≈4 MP | $0.0027/img | −84% |
- Official price: BFL API list price for FLUX.2 [klein] 4B ($0.014 for the first output megapixel, $0.001 per additional MP; input images at $0.001 / MP). Prices verified 2026-10-16.
Related models

FLUX.2[pro]
Text → Image · Image Edit
Black Forest Labs' production image model — photoreal, fast, up to 4 MP

Krea 2Turbo
Text → Image
Krea's photographic image model in 8 steps — under a cent an image

Z-ImageTurbo
Text → Image
Alibaba's 6B open model — photoreal images in 8 steps for a fraction of a cent
