Flux 2 Flex Text to Image

bfl/flux-2/flex

Flux 2 Flex is BFL's advanced text-to-image AI model. Create photorealistic images, illustrations, and concept art from natural language descriptions with exceptional detail and prompt adherence.

Base price
$0.06USD / run
Execution
async
Model type
image
Input fields
6
Production route

Try the model

Playground

Open playground
Input
The prompt to generate an image from.
1.510
The guidance scale to use for the generation. Range: 1.5 to 10.
250
The number of inference steps to perform. Range: 2 to 50.
The format of the generated image. Allowed values: jpeg, png.
The aspect ratio of the generated image. Allowed values: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16.
The seed to use for the generation.
OutputExample

Examples

Select an example to load its inputs and result into the playground.

Model card

Specifications

Pricing

Base price
$0.06 / run

Context & modalities

Input
Schema-defined
Output
image

Capabilities

Chat
Not supported
Vision
Not supported
Reasoning
Not supported
Structured output
Not supported
Function calling
Not supported
Audio input
Not supported

Access

Provider
BFL
Model ID
bfl/flux-2/flex
Execution
async
Base URL
https://api.sandbase.ai
API
Unified Run API
Endpoint
/v1/run

Human preference

Arena

Elo ratings from blind side-by-side votes, compared with other image and video models.

Rankings sourced from Artificial Analysis Arena

Leaderboard
Text to Image
Rank
#29 of 106
Elo
1026 ±11
Gap to #1
−196

Text-to-image arena: people pick the better of two images generated from the same prompt, without seeing the model names.

  1. #24Krea 2 LargeKrea1034±9
  2. #25Qwen Image 2.0 Pro (2026-04-22)Alibaba1030±11
  3. #26MAI-Image-2.5-FlashMicrosoft AI1029±11
  4. #27Qwen-Image-2.1-TurboAlibaba1029±12
  5. #28Wan 2.6 ImageAlibaba1027±12
  6. #29FLUX.2 [flex]Black Forest LabsThis model1026±11
  7. #30Ideogram 4.0 (Quality)Ideogram1026±10
  8. #31Recraft V4.1 UtilityRecraftOn SandBase1026±11
  9. #32Seedream 4.5ByteDance SeedOn SandBase1026±12
  10. #33Luma UNI 1 MaxLuma Labs1023±12

API README

Flux 2 Flex Text to Image

FLUX.2 [flex], the tunable tier: adjust steps and guidance for typography-heavy or detailed work. Text to image.

Fields

FieldTypeDefaultNotes
promptstring, required—Text instruction.
guidance_scalenumber 1.5–103.5How strictly to follow the prompt.
num_inference_stepsinteger 2–5028More steps add detail and time.
output_formatjpeg / pngjpegOutput file format.
aspect_ratio21:9 / 16:9 / 3:2 / 4:3 / 5:4 / 1:1 / 4:5 / 3:4 / 2:3 / 9:1616:9Output shape.
seedintegerrandomFix it to compare prompt changes.

Billing

$0.06 per image.

RequestPrice
One image$0.06

Failed runs are not charged.

Prompting

  • Write subject, setting, composition, style, then light.
  • Quote any text that must appear.

Limits

  • One output image per request.

Also on SandBase

Other FLUX.2 endpoints: bfl/flux-2/max, bfl/flux-2/pro, bfl/flux-2/dev, bfl/flux-2/turbo, bfl/flux-2/flex/edit.

Start building

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

Production API
Unified Run API endpoint
https://api.sandbase.ai/v1/run
Model ID
bfl/flux-2/flex
# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "bfl/flux-2/flex",
  "prompt": "A high-quality 3D render of a cute fluffy monster eating a giant donut; the fur simulation is incredibly detailed, the donut glaze is sticky and reflective, bright daylight lighting, shallow depth of field.",
  "aspect_ratio": "16:9",
  "output_format": "jpeg",
  "guidance_scale": 3.5,
  "num_inference_steps": 28
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"

Choose your model

Compare models

All image & video models
ModelTypeDefault priceReleased
BFLImage$0.06 / runNov 25, 2025
BFLImage$0.05 / runOct 1, 2026
BFLImage$0.05 / runOct 1, 2026
BFLImage$0.02 / runJan 15, 2026
BFLImage$0.02 / runJan 15, 2026
BFLImage$0.01 / runJan 15, 2026

Questions

FAQ

How do I call BFL Flux 2 Flex Text to Image through SandBase?

Create a SandBase API key, then send requests with the model ID "bfl/flux-2/flex" to Unified Run API (/v1/run) at https://api.sandbase.ai. The request examples on this page show the exact payload.

Do I need a separate BFL account?

No. One SandBase API key and balance gives you access to BFL Flux 2 Flex Text to Image and the other models in the catalog; you do not need to sign up with BFL separately.