Is a 9:16 Seedance clip cheaper than 16:9? Pixel math on Sume

No. At 720p a 10-second Seedance 2.5 clip costs $5.778 in 9:16, 16:9 and 1:1 on Sume. The token count per second is 21,600 for all three, so the price is the same. Only 4:3, 3:4 and 21:9 differ, by under 1 percent.

This matters when you plan one Black Friday concept in several placements: vertical, landscape and square cost the same to render.

Why the count matches

Seedance 2.5 on Sume is billed per 1,000 video tokens, and tokens per clip are ceil(width x height x seconds x 24 / 1024). Vertical and horizontal frames use the same pixels, only rotated, so 1280 x 720 and 720 x 1280 are both 921,600 pixels. The 1:1 frame at 960 x 960 is also 921,600 pixels.

The other ratios land on slightly different pixel counts. The video model docs list the supported ratios.

The multiplication, step by step

For 9:16 at 720p: 720 x 1280 = 921,600 pixels. Times 24 frames, divided by 1,024, gives 21,600 tokens per second. For 10 seconds that is 216,000 tokens.

At the $0.0214 list rate per 1,000 tokens, that is 216,000 x 0.0214 / 1,000 = $4.6224. Sume then multiplies by 1.25 to reach $5.778.

What to do with this

• Pick the ratio for the placement, not for the price: the render is the same cost.
• Generate the ratios you will ship as separate jobs. Re-framing one render by cropping loses pixels.
• For 21:9 expect $0.028222 extra per 10 seconds over 16:9.

Resolution is the real lever

Moving from 480p to 720p multiplies a 9:16 clip price by 2.15. Price the resolution you will actually publish, since that is where the budget moves.