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Model comparisons

FLUX.2 Klein 9B vs FLUX.2 Pro

FLUX.2 Klein 9B: Uncensored. FLUX.2 Pro: Filtered. FLUX.2 Klein 9B lists a 71% lower unit price than FLUX.2 Pro.

FLUX.2 Klein 9B

FLUX.2 [klein] 9B image editing takes one to three source images and an instruction, keeping a person's face and pose while the clothes, room or light change. Edits usually return in well under a minute.

View model details →View sample outputs →

FLUX.2 Pro

FLUX.2 [pro] edit takes one to three source images and an instruction such as a new setting, new light, added text or a combined scene, keeping the source shape or a shape you choose.

View model details →View sample outputs →

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The short answer

Start with the input you have, the result you want and your budget. These are the differences that affect that choice.

  • FLUX.2 Klein 9B is listed as Uncensored; FLUX.2 Pro as Filtered. Compare the examples and content-test details on each model page for the scenes you want to create.
  • FLUX.2 Klein 9B has the lower listed unit price by 71%.

Compare the published examples, then try the same input on both models with matching settings.

Test scores side by side

The Spicy Index and Freedom Score for both models, from the same daily calculation as the leaderboards.

Test scores side by side
MeasureFLUX.2 Klein 9BFLUX.2 Pro
Spicy Index65.052.3
Freedom Score84.034.1
EvidenceTested 6 of 6 probe types · 50 runsTested 6 of 6 probe types · 50 runs
Range if the rest pass84.0–84.034.1–34.1
Price$0.011 per image$0.03 per image
ReviewsRead the FLUX.2 Klein 9B reviewRead the FLUX.2 Pro review
See both on the leaderboard →

Current price

Price at the same setting

A start price answers a different question than the one you have. These are the tiers both models publish, matched setting for setting, in US dollars per billed unit with no conversion step in between.

Swipe horizontally to compare all fields.

Price at the same setting
TierFLUX.2 Klein 9BFLUX.2 ProDifference
Current price$0.016 / output images$0.058 / output imagesFLUX.2 Klein 9B −71%

What one ordinary job costs

  • FLUX.2 Klein 9B: $1.63 for one hundred images.
  • FLUX.2 Pro: $5.78 for one hundred images.

Arithmetic on the published rates at each model's own default setting, not a quote. The console prices your actual settings before a request is accepted.

About this comparison

Controls and limits

Every row here is read from the JSON Schema the endpoint validates against, so it matches what the API will really accept rather than a feature list written by hand.

Swipe horizontally to compare all fields.

FLUX.2 Klein 9B vs FLUX.2 Pro
Controls and limitsFLUX.2 Klein 9BFLUX.2 Pro
Supported tasksimage-to-imageimage-to-image
Resolution tiers1K · 2K1K · 2K
Aspect ratiosauto · 1:1 · 16:9 · 9:16 · 4:3 · 3:4 · 3:2 · 2:3 · 21:9 · 9:21auto · 1:1 · 16:9 · 9:16 · 4:3 · 3:4 · 3:2 · 2:3 · 21:9 · 9:21
Reference materialUp to 3 filesUp to 3 files
High-resolution tierYesYes
SeedYesYes
ExecutionSubmit, then poll or take the callbackSubmit, then poll or take the callback
Request timeout30 minutes30 minutes
AvailabilityLiveLive

Do low-filter models allow every request?

Content policy, side by side

Two separate facts sit behind these labels. The first is what we do, which is nothing: no platform content filter, and no maturity flag to set on a request. The second is what each model does on its own, and that is the only part that varies between these two.

FLUX.2 Klein 9B

Uncensored

This model declares no content filter. SpicyAPI forwards the request without adding a platform content scan; legal and consent duties remain with the customer.

FLUX.2 Pro

Filtered

This model refuses requests beyond its own limits outright. Measured, not assumed — models we have not measured carry no label at all.

Use these content labels to shortlist models, then open each model page for available examples and content-test details.

The label never changes your obligations. Age, consent, real-person likeness and the law where you operate stay with you, and SpicyAPI does not inspect each request.

Can I swap the model ID without changing the request body?

Request body, field by field

The task lifecycle is shared; the body is not. Each endpoint publishes its own JSON Schema and the API validates against that, so this is the list to reconcile before a switch.

  • 5 fields appear in both request bodies under the same names. aspect_ratio, image_urls, prompt, resolution, seed
  • FLUX.2 Klein 9B accepts no field the other one lacks.
  • FLUX.2 Pro accepts no field the other one lacks.
  • FLUX.2 Klein 9B requires image_urls, prompt.
  • FLUX.2 Pro requires image_urls, prompt.
  • Both reject unknown fields outright, so a parameter left over from the other model comes back as a validation error instead of being quietly ignored.

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Moving from one to the other

The model identifiers are black-forest-labs/flux-2-klein-9b/edit and black-forest-labs/flux-2-pro/edit, and both go in the same field of the same request.

Both run the same way: submit the task, then poll it or take the callback. Queueing and retry logic carry over unchanged.

Both use the same submit-and-track flow, but their required inputs may differ. Check each model page before switching.

One key, one balance, one set of spend caps. Both bill to the same account in US dollars, and the per-key daily, monthly and lifetime limits apply to whichever one you call.

Questions developers ask

Which is cheaper, FLUX.2 Klein 9B or FLUX.2 Pro?

Which is cheaper, FLUX.2 Klein 9B or FLUX.2 Pro?

FLUX.2 Klein 9B has the lower listed unit price by 71%. Prices may change; check the estimate shown for your actual settings before submitting.

How long can a single request run?

FLUX.2 Klein 9B allows 30 minutes per task and FLUX.2 Pro allows 30. Those are ceilings rather than typical times — most requests finish far sooner — but they are what your own client timeout has to survive.

Prices and capabilities shown here come from the current public model catalogue. Check each model page for its latest inputs and examples.

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