Ceil to the cent on 3-second Wan clips: 37.5 cents becomes 38

A 3-second wan-3.0 clip at 720p costs 38 cents on Sume, not 37.5. The list price is $0.10 per second, so 3 seconds is $0.30, times 1.25 is $0.375, and Sume rounds that up to the next cent for each clip. Over 1,000 such clips the round-up adds $5.00 to a $375.00 sum.

Short clips are where this shows. A re-render of a library full of hooks and stingers, after OpenAI removed the Videos API and the sora-2 family on 2026-09-24, can have thousands of 2- and 3-second prompts, and the round-up is a fixed fraction of a cent on each.

The rule

The Sume docs state the billing as the provider list price times 1.25. The catalog turns that into whole cents per clip, rounding up. That is why 8-second wan-3.0 clips at 720p are exactly 100 cents but 3-second clips are not a clean multiple.

Where the round-up is zero

The round-up vanishes when the product of list price, seconds and 1.25 is already a whole cent. Wan 3.0 at 1080p is $0.20 per second, so 3 seconds is $0.75 exactly, and the clip bills at 75 cents with nothing added. An 8-second wan-3.0 clip is exact at all three tiers: 50, 100 and 200 cents.

The lesson is not to avoid short clips but to price them from the catalog, not from the per-second list. A sum of per-second prices times total seconds will undercount a library of short clips by up to 1 cent per clip.

A rule of thumb for budgets

The round-up is less than 1 cent per clip, so it can be at most 1 cent times the clip count: $10.00 for 1,000 clips, and less when the clip lengths are mixed. For long clips, it is a rounding error. For 3-second clips at 480p it is 0.25 cent each, $2.50 per 1,000.

If you are budgeting a library, take the price of each clip from the GET /v1/videos/models response or from the grid for its exact length, multiply by the clip count, and add the lines. Do not multiply a library-wide seconds total by a per-second rate.

• Exact multiples: wan-3.0 at 8 s (50, 100, 200 cents) and at 1080p for any whole second.
• Rounded up: wan-3.0 at 3 s for 480p and 720p; gemini-omni-flash-1.1 at 360p for 3 s.
• The round-up is applied per clip, so batching does not remove it.