Seedance 2 at 1080p: 14 s fits a $12 balance, 15 s returns 402

With $12.00 in the workspace, a 14-second Seedance 2 clip at 1080p goes through and a 15-second one fails with 402 insufficient_credits. The rate is $0.8505 per output second: 14 x $0.8505 = $11.907, and 15 x $0.8505 = $12.7575, which is $0.7575 more than the balance.

Fifteen seconds is the top of the model's 4-15 second window, so this is the longest single 1080p Seedance 2 clip you can ask for, and it is the one that fails first on a small balance.

The same $12 at each resolution

The 402 is a property of 1080p, not of the model. At lower resolutions the full 15 seconds fits easily.

What the 402 means

The errors page lists 402 insufficient_credits as a balance that is not sufficient for the requested generation. The admission docs add the mechanism: Sume cannot reserve the estimated generation cost from the workspace balance, so the request fails before provider work starts. Nothing is generated and nothing is charged.

The fix is on your side: shorten the clip, lower the resolution, or add funds in the dashboard. The documented client behavior is to submit a less expensive request rather than retry the same one.

A check before you submit

Because video is linear in seconds inside the window, you can compute the longest affordable clip from the balance. This sketch uses the rate in the table; read the live rate from the catalog before trusting it.

# Longest seedance-2 1080p clip a balance can reserve
RATE_1080P = 0.8505   # USD per second, Sume list as of 2026-10-09
MIN_S, MAX_S = 4, 15  # seedance-2 duration window

def longest(balance):
    secs = int(balance // RATE_1080P)
    return secs if secs >= MIN_S else 0

balance = 12.00
secs = min(longest(balance), MAX_S)
print(secs, "s costs", round(secs * RATE_1080P, 4))
print(15, "s costs", round(15 * RATE_1080P, 4), "-> 402 on a $12 balance")

Scope of the claim

The reservation is the estimated amount, and a completed job captures the reserved usage. Other holds count too: if three other jobs are in flight, their reservations come out of the same balance, so the usable figure is the balance minus open holds, not the headline number.

Planning a small balance

On a small balance the cheapest sensible workflow is to settle on a prompt at 480p, where a full 15-second Seedance 2 clip costs 15 x $0.17577 = $2.63655, then spend the remainder on one 1080p render. With $12.00 that is one 480p draft ($2.63655) followed by one 1080p clip of up to 11 seconds (11 x $0.8505 = $9.3555), which together total $11.99205. Skipping the draft lets you buy the 14-second 1080p clip instead.

Neither plan is free of risk: a failed job releases its reservation, but a completed clip you dislike is already captured. Budget for the number of attempts you expect, not for one perfect take.

Seedance 2.5 on the same balance

The newer seedance-2.5 costs more per second, $1.42155 at 1080p, so $12.00 buys 8 seconds ($11.3724) and the 9-second clip needs $12.79395. The model has a 4-second minimum billed, so very short clips are not cheaper than they look: a 3-second request is billed as 4. Whichever model you choose, the order of operations is the same: price in seconds, compare to the balance minus open holds, then submit with an Idempotency-Key so a retry after a timeout cannot create a second paid job.