Seedance 2.5 or 2.0 on Sume: 30 s vs 15 s, $0.58 vs $0.38 a second

Short answer

Pick seedance-2.5 when you need clips longer than 15 seconds, and seedance-2 when 15 seconds is enough and you want the lower rate. The Sume docs list seedance-2.5 at 4 to 30 seconds at 480p, 720p and 1080p, and each other catalog model, seedance-2 included, at a maximum of 15 seconds. seedance-2 also has 1080p (Video Router docs).

Price at 720p

Seedance is billed by video tokens. In Sume's rate table the list rate is $0.0214 per 1,000 tokens for 2.5 and $0.014 for 2.0, and Sume bills list times 1.25. At 24 frames per second and 1280x720 that is about 21,600 tokens a second. The per-clip arithmetic follows; the live reserve is what counts, and GET /v1/videos/models shows pricing_skus for each model.

What 2.5 adds

ByteDance's Seedance 2.5 announcement (read 2026-10-05) lists audio-video joint generation, up to 30 seconds per generation, up to 30 images, 10 video clips and 10 audio clips as references per pass, plus timestamp-level editing and green-screen background replacement. It does not state a price, and says the API is coming via BytePlus ModelArk. Which of those features are reachable through Sume is defined by the catalog: read each model's capabilities from GET /v1/video-router/models, since Sume does not promise the vendor's full feature list.

Decision table

• Clip over 15 seconds: seedance-2.5; there is no longer option in the Seedance 2.0 line.
• Clip of 15 seconds or less, no special need: seedance-2, about a third cheaper per second at 720p.
• 1080p final: both have it; for 2.5 the list rate steps up from $0.0214 to $0.0234 per 1,000 tokens at 1080p.
• Drafting: draft on the model you will finish with, since neither accepts seed.

A worked comparison

A 12-second 720p clip is $6.93 on seedance-2.5 and $4.54 on seedance-2, a $2.40 difference. A batch of 25 is $173.25 against $113.40. For a 20-second clip, only seedance-2.5 is possible, at $11.56 for 720p. The alternative on seedance-2 is two clips joined with Timeline 1.0, which adds $0.10 per output minute rounded up, but the two takes may not match in motion.

The decision therefore turns on whether you need the longer single take.

Cost per second is only one input. If the clip you need is 12 seconds or shorter and the reference features are not required, the older model is cheaper per second and nothing is lost. If you need the longer single take or the extra control, the premium buys something concrete. The mistake to avoid is defaulting to the newest model for every job, which multiplies cost without a matching gain.

Compare on your own prompts. Run five clips on each at 720p, read the captured amounts, and decide whether the output difference justifies the gap for your content.

For budgeting, write the two rates down as dollars per second at your resolution and keep them in one config file. At 720p the figures are about $0.58 and $0.38, and a team that can name them can answer a producer's question about a 20-second request in seconds. The longer duration limit also changes how you plan scenes: a 30-second take needs no joins, while a 15-second ceiling means a join at the cut, with the small mismatch risk that brings.