FLUX.2 klein API price: $0.014 plus per megapixel, and Sume

BFL's FLUX.2 overview lists the klein API prices as $0.014 + $0.001 per megapixel for the 4B model and $0.015 + $0.002 per megapixel for the 9B model, with "from $0.014 / image" as the headline. So a 1 MP image is $0.015 on 4B and $0.017 on 9B by BFL's own formula. Sume's Image API does not list klein: its FLUX ids are black-forest-labs/flux.2-pro and black-forest-labs/flux.2-flex, with per-image prices on the catalog endpoint.

BFL's figures are from its FLUX.2 overview, read 2026-10-02. Sume's catalog behavior is from the Sume Image API page, read the same day.

What does BFL charge for klein?

BFL's model table gives both klein sizes a base price plus a per-megapixel price. Both are step-distilled to 4 steps with sub-second inference, and the page says klein has no prompt upsampling, so write detailed prompts. The 4B model is Apache 2.0; the 9B is under the FLUX Non-Commercial License. The table below works the arithmetic for three output sizes.

Does Sume list FLUX.2 klein?

No. The OpenAPI model enum for POST /v1/images names black-forest-labs/flux.2-pro and black-forest-labs/flux.2-flex for FLUX, and no klein id. Sume's catalog is read from GET /v1/images/models, so check there before you plan a pipeline around a model, since the list changes over time.

How do I read the Sume price for a FLUX model?

Call GET /v1/images/models/black-forest-labs/flux.2-pro/endpoints and read the pricing line. The docs say endpoint pricing lines are what is charged to your wallet, with Sume's margin already applied, so cost_usd times n is what you pay. Sume's catalog prices are per image, not per megapixel, so do not compare them line by line with BFL's per-megapixel formula.

When would klein be the right tool?

BFL positions klein for real-time and high-volume generation and for local deployment: the 4B model's weights are Apache 2.0, and BFL says it runs on consumer GPUs at about 13 GB of VRAM. If you need that, call BFL or run the weights yourself. If you need a FLUX model through Sume, FLUX.2 pro or flex is what the catalog offers.