Poster motion: Seedance 2.5 at 3:4 costs 0.6% more than 9:16 at 720p

At 14 seconds, a 3:4 Seedance 2.5 clip costs $8.14 at 720p against $8.09 for 9:16, a gap of $0.05. At 480p the order reverses and 3:4 is cheaper (read 2026-10-09).

3:4 and 9:16 are not priced the same

Poster motion, print-ad previews and product cards are often 3:4; Reels and Shorts are 9:16. Both are in the Seedance 2.5 ratio list, but the token formula treats the two frames differently, so the quote changes with the ratio you choose.

Ask the price tool before the bulk run

The gap is small per clip but adds up in a batch. Call the same body with each ratio and compare usage.cost on the completed responses.

import os, time, requests

API = "https://api.sume.com/v1/videos"
H = {"Authorization": "Bearer " + os.environ["SUME_API_KEY"]}
body = {"model": "seedance-2.5", "prompt": "A vintage travel poster comes alive: clouds drift, a boat rocks, ink-like paper texture", "duration": 14, "resolution": "720p", "aspect_ratio": "3:4"}
job = requests.post(API, headers={**H, "Idempotency-Key": "poster-motion-34-001"}, json=body, timeout=60).json()
deadline = time.time() + 1800
while time.time() < deadline:
    time.sleep(30)
    job = requests.get(job["polling_url"], headers=H, timeout=60).json()
    if job["status"] == "completed":
        print(job["unsigned_urls"][0], job["usage"]["cost"])
        break
    if job["status"] in ("failed", "cancelled"):
        print(job["status"], job.get("error"))
        break

What the gap means for a 100-poster batch

For 100 posters at 14 seconds and 720p, the 9:16 batch costs $808.92 and the 3:4 batch $814.02. The difference is $5.10. At 1080p the same comparison is $1990.17 against $2002.71.

At 480p it flips: 100 clips cost $376.15 in 9:16 and $369.63 in 3:4. A proof round at 480p in the ratio you will ship costs a little less than in 9:16.

The lesson is to budget in the real ratio. Do not price a 3:4 job from a 9:16 table, and do not price a 720p job from a 480p table.

Gotchas

• At 720p and 1080p the 3:4 price is about 0.6 percent higher than 9:16; at 480p it is lower. The same direction holds for 4:3 against 16:9.
• Do not crop a 9:16 clip to 3:4 to save money; generate in the ratio you publish, or check the crop is acceptable first.
• 14 seconds is a valid length because Seedance 2.5 takes every whole second from 4 to 30.
• The reservation at submit equals the full list price times 1.25, so a 14-second 1080p job needs the whole amount in the balance.