Why Does FASHN Model Create Stop at 2K When I Provide face_reference and Request 4K?

Identify the Conditional Resolution Limit

In Model Create, supplying face_reference caps output at 2K regardless of the requested resolution tier. This is an endpoint-specific condition, not a restriction established for every FASHN endpoint.

The documentation describes 1k, 2k and 4k as approximately 1, 4 and 16 megapixels. Exact width and height depend on aspect ratio, so 2K is not one universal pixel rectangle. A tier name alone cannot establish whether a particular delivery specification is met.

1. Record the Model Create request, whether face_reference was supplied, and the requested resolution and aspect_ratio values.
2. Obtain the approved destination ratio and minimum width×height, and record whether native dimensions or an enlarged derivative are acceptable.
3. If an output is produced, inspect its actual width×height and keep the source output separate from any enlarged derivative. Compare those observations with the approved delivery requirement.
4. If the identity requirement and native delivery specification conflict, keep approval pending while the campaign owner chooses an acceptable production approach; do not silently remove face_reference.

Check the face-reference cap and resolution-tier definitions in FASHN Model Create resolution conditions.

When specifying delivery, separate aspect ratio from returned pixel dimensions rather than treating a tier label as a fixed file size.

Separate Identity Approval From Pixel Requirements

A merchant may require a specific approved face because the campaign features a recognizable representative. Another campaign may prioritize a large display surface without requiring a particular person's identity.

These are different production requirements. Do not silently remove face_reference merely to pursue a higher tier. Instead, ask the campaign owner which requirement is mandatory and document the resulting decision.

A higher pixel count is also not proof of accurate product details. Likewise, enlarging a smaller output during post-production does not reconstruct native detail that was never present.

Illustrative Exercise: Two Advertising Briefs

Illustrative exercise, not an API or export test: one campaign requires an approved representative's face, while another has no mandatory identity but prioritizes native delivery dimensions. The table summarizes those different priorities. For either brief, enter an actual approved ratio and minimum width×height before deciding whether the chosen workflow is suitable; no output dimensions are predicted here.

Record the Constraint Before Delivery

The handoff should distinguish requested resolution, documented maximum under the selected conditions, actual output properties, and final placement requirements. Do not label an enlarged derivative as native 4K.

If the approved identity and required native resolution cannot both be satisfied through the selected workflow, escalate the conflict before committing the asset to production.

Review the delivered file's actual dimensions and relevant product details independently. The documented Experimental Model Create behavior, released August 11, 2025, explains the conditional cap but does not establish an output result for these fictional cases.

Identity and native-dimension record — complete with actual observations

Save a copy of this record and enter actual inputs, actions and observations. Keep incomplete checks pending; do not prefill success.

Download review worksheet (CSV)