Runway Seedance 2.5: 20 credits plus input at 480p; what input adds

Runway's Seedance2_5 row reads "20/30/68 plus input" for 480p, 720p and 1080p, which is $0.20, $0.30 and $0.68 per second at $0.01 per credit, plus a charge for input that the pricing guide does not quantify. I will not guess that number. On Sume, seedance-2.5 is billed by video tokens, and a request with a reference video adds 15 assumed input seconds and a 0.6 multiplier.

What Runway lists

Runway values are from the Runway API pricing guide.

What input does on Sume

seedance-2.5 takes 4 to 30 seconds at 480p, 720p and 1080p. Its list is $0.0214 per 1,000 video tokens, and $0.0234 at 1080p, from Sume's pricing table. The token count is (width x height x seconds x 24) / 1024 for the output frame size. For a reference video, Sume's pricing code counts the output seconds plus 15 assumed input seconds, then multiplies the cost by 6/10.

These are estimates from the rate card. The live figure is in GET /v1/videos/models.

What the arithmetic says

With a 10 second output, a reference video raises the estimate from $5.778 to $8.667, which is a factor of 1.5 (25 seconds x 0.6 = 15, against 10). With a 4 second output the factor is 2.85 (19 x 0.6 = 11.4, against 4), because the 15 assumed seconds dominate a short clip.

So the adder hurts most on short clips: a short clip with a reference video pays for the 15 input seconds that the estimator assumes, whatever the real input length.

Practical rule

Plan around two facts: Runway's input charge is not quantified in the guide, and Sume's reference-video adder is a 15 second assumption with a 0.6 multiplier. Use a still frame or an image reference when the video is not essential, and ask for a quote from the catalog before a large run.