Splitting a 30-second Wan 3.0 job adds cents from per-job rounding
Wan 3.0 bills linearly per second, but Sume rounds each job up to the cent. A 30 s clip as six 5 s jobs costs $3.78 at 720p instead of $3.75. Full split table.
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.
| Plan | 480p total | 720p total | 1080p total |
|---|---|---|---|
| 1 x 30 s | $1.88 | $3.75 | $7.50 |
| 2 x 15 s | $1.88 | $3.76 | $7.50 |
| 3 x 10 s | $1.89 | $3.75 | $7.50 |
| 5 x 6 s | $1.90 | $3.75 | $7.50 |
| 6 x 5 s | $1.92 | $3.78 | $7.50 |
| 10 x 3 s | $1.90 | $3.80 | $7.50 |
| 15 x 2 s | $1.95 | $3.75 | $7.50 |
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.
Sources
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