FLUX.2 pro vs flex: which model id to send on Sume and what you lose

Send black-forest-labs/flux.2-pro for general generation and editing, and black-forest-labs/flux.2-flex when you need small text or fine detail. Black Forest Labs describes flex as specialised for typography and pro as the production default, and lists both with up to 8 references through the API (read 2026-10-03). The catch on Sume: flex's adjustable steps and guidance are not passed through, because Sume's provider.options must be empty, so on Sume the two differ by model, not by tuning (BFL overview).

What the vendor page says

BFL's comparison table gives pro from $0.03 per megapixel and flex $0.06 per megapixel, a 4 megapixel output ceiling for the FLUX.2 family, and flex as the model with adjustable steps and guidance (read 2026-10-03). Those are BFL's rates, not Sume's.

What Sume does

Sume prices each completed image at a flat catalog rate: FLUX.2 pro $0.04 and flex $0.07 after the 1.25 factor and the round-up to a cent. Both take the same aspect ratios, including 1:1, 16:9, 9:16, 4:3, 3:4, 4:5, 5:4, 3:2, 2:3, 21:9, 9:21, 1:2 and 2:1, and both edit from references (Image API).

How to choose

Run the same prompt on both with your real copy. If pro renders the text correctly, stay on pro and save about 40 percent. If text breaks, move that one asset to flex. For a heavy text job, also test a model built for it; the stored comparison covers Ideogram, Recraft, Qwen and Seedream as well (which model for text).