Splitting a 30-second Wan 3.0 job adds cents from per-job rounding

Splitting one 30-second Wan 3.0 job into shorter jobs never makes it cheaper, and it sometimes adds a few cents. Wan 3.0 pricing is linear per second, but Sume reserves and bills each job separately and rounds each one up to the cent. Six 5-second jobs at 720p cost $3.78 where one 30-second job costs $3.75.

That extra is small, so the decision to split should come from creative needs. This post shows exactly where the cents come from so you can tell a budget line from rounding noise.

Where the rounding happens

The per-second price at 720p is $0.10 x 1.25 = $0.125. A 5 s job is $0.625, which Sume rounds up to $0.63. Six of them are $3.78. A 10 s job is exactly $1.25, so three of them match the single job at $3.75. At 480p the per-second price is $0.0625, which does not divide into whole cents for many durations, so most splits add something: the 2 x 15 s split is the exception because 15 s lands on $0.9375 and the pair rounds to $1.88.

At 1080p the per-second price is $0.25. Every whole-second duration lands on a quarter, so each split sums to $7.50 and rounding never shows up.

Reading the table

The 480p column is where this matters most, because 480p is the tier people use for drafts. If you run 100 drafts a day split into 5 s jobs, 100 x $0.32 = $32.00 against 100 x $0.3125 = $31.25 if each job could bill without rounding up, so the rounding adds about two percent to the draft bill.

The worst split in the grid is fifteen 2-second jobs at 480p: each costs $0.13 (0.125 rounded up), so the total is $1.95 against $1.88. Fifteen jobs also mean fifteen reserves, fifteen polls and fifteen chances to submit a retry, which is a larger cost than the cents.

Wan 3.0 accepts 2 to 30 seconds per job, so every row above is a valid request. A split also means that continuity between segments is your problem: each job starts fresh unless you pass a first frame or reference images.

When splitting is still the right call

• You want to approve scenes one at a time and re-run only the weak one.
• A segment fails: Sume refunds failed jobs, so a failed 5 s job costs nothing and retries cheaply.
• Cancel only works before generation starts, so a long single job cannot be stopped midway.
• You need different references or frames for different shots.

For the opposite case, see the 30 s versus three 10 s comparison.