3-second clip: Wan 3.0 $0.375 vs Seedance 2.5 at its 4 s floor

On Sume a 3-second 720p clip on wan-3.0 costs $0.375 (3 x $0.125). seedance-2.5 does not accept 3 seconds: its range is 4 to 30 seconds, so the shortest valid clip is 4 seconds at 720p, $2.3112 (4 x $0.5778), which is 6.16 times the Wan figure. If you want a short cut-in or a reaction beat, that floor is the number that matters, not the per-second rate.

Shortest valid clip on each tier

The table shows the minimum duration each model accepts, priced at the three resolutions both models list.

Per-second parity point

The per-second ratio between the models is 4.30 at 480p, 4.62 at 720p and 5.69 at 1080p. The shortest-clip ratio is higher because Seedance 2.5 is billed for at least 4 seconds. To buy the same 4 seconds on Wan 3.0 at 720p you would pay $0.50, so the ratio at equal duration is 4.62.

That means the floor penalty is only for clips shorter than 4 seconds. At 4 seconds and above, you are comparing like with like on length, and the question becomes whether the Seedance 2.5 output is worth 4.62 times the price. This post has no source for that claim, so test it on your prompts.

Requesting a short Wan clip

Send duration 3 and the resolution you want. Seedance 2.5's documented range starts at 4 seconds, so read each model's range from the model list rather than hard-coding it.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: wan-3s-720p" \
  -d '{
    "model": "wan-3.0",
    "prompt": "A vertical product clip on a desk, natural light",
    "resolution": "720p",
    "duration": 3,
    "aspect_ratio": "9:16",
    "mode": "async"
  }'

Batch totals

Fifty 3-second 720p clips on wan-3.0 are 50 x $0.375 = $18.75. Fifty 4-second clips on seedance-2.5 at 720p are 50 x $2.3112 = $115.56. Wan 3.0 also accepts audio and video references, as does Seedance 2.5, so reference inputs are not what separates them here.

A 12-clip storyboard example

Say a storyboard has twelve 3-second cutaways. On wan-3.0 at 720p they cost 12 x $0.375 = $4.50. If you rounded each one up to the 4-second Seedance 2.5 floor, the set is 12 x $2.3112 = $27.7344. The same twelve at 480p are $2.25 on Wan 3.0 and $12.896496 on Seedance 2.5.

The cheap way to use Seedance 2.5 for a short beat is to generate a longer clip and trim it. A 4-second Seedance 2.5 clip trimmed to 3 seconds adds one video trim job at $0.02, so the real cost of a 3-second Seedance shot at 720p is $2.3112 + $0.02 = $2.3312.