Kling 4.0 Flash closed beta: Ultra yearly only, and Sume options

Short answer

Kling 4.0 Flash has been in a closed beta for Ultra yearly subscribers since Sep 28, with clips of 3 to 20 seconds at 720p in 8-bit SDR and no published API price, per fal's Kling 4.0 guide (read 2026-10-04). If you are not on that plan, you cannot test it. On Sume, wan-3.0 and seedance-2.5 both cover 20 seconds; kling-3 stops at 15.

Who can use it, and when

Access is gated by the plan tier, not by an application form that fal describes. Full Kling 4.0 is expected in October with up to 30 seconds, up to 4K, up to 10 keyframes and extension coming later. Flash is described as the faster variant, so treat it as a preview of speed, not of the full feature set.

What reaches 20 seconds on Sume at 720p

Sume docs give wan-3.0 a 2 to 30 second range and seedance-2.5 a 4 to 30 second range. At 720p Wan bills $0.125 a second and Seedance 2.5 bills 21,600 tokens a second at $0.0214 per 1,000 list, times 1.25, which is $0.5778 a second at 16:9.

Steps to use the closest thing today

• Decide whether you need Kling's look or only the length. If only length, send duration: 20 to wan-3.0.
• Read the catalog for supported_durations before you submit.
• Draft at 480p first: Wan 3.0 is $0.0625 a second there, so a 20 second draft is $1.25.
• Keep the model id in config so you can swap in a Kling 4.0 id if Sume lists one.

curl -X POST https://api.sume.com/v1/videos \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"wan-3.0","prompt":"A lighthouse in a storm","duration":20,"resolution":"720p"}'

A fallback plan for a 20-second brief

If a client wants 20 seconds and mentions Kling 4.0 Flash, split the question. Ask whether the look comes from Kling or the length does. For length, wan-3.0 is the cheapest at $2.50 for 20 seconds at 720p. For a premium look, seedance-2.5 is $11.56 for the same length. If neither matches, wait for a public Kling 4.0 id, and keep the brief in a form that survives a model swap: prompt, reference images and a length.

Caveats

Kling's own release-notes page did not render its body, so beta details here are fal's. Output quality and motion style differ by model; a length match is not a quality match.