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How Long Can Seedance Videos Be? 2.0 at 15s, 2.5 at 30s
2026/07/03

How Long Can Seedance Videos Be? 2.0 at 15s, 2.5 at 30s

Seedance 2.0 generates 4–15 seconds per request; Seedance 2.5 supports 4–30 seconds. See duration settings, current costs, and scene chaining.

Seedance 2.0 videos can be 4 to 15 seconds long per generation, while Seedance 2.5 extends the live reAPI route to 30 seconds.[1][7] The 2.0 limit is a model cap rather than a subscription setting; choose 2.5 when a 16–30-second single take removes a join.

The more useful questions sit around those limits: what duration costs, how productions get past one model's ceiling, whether Runway's extend feature applies (short answer: no), and when 2.5 is the better route. All four, sourced, below.

TL;DR

  • The range is 4–15 seconds per generation, 24fps, default 5s, across the Seedance 2.0 routes[1]. reAPI accepts whole seconds in that range; on doubao-seedance-2.0, -face and -official you can also pass -1 to let the model pick the length (credits are held at the 15-second cap and settled to the delivered length). Anything else is rejected with HTTP 400 and code 20003, and nothing is charged.
  • You pay by the second, so a 15-second no-source clip costs exactly 3x a 5-second clip at the same tier; current reAPI examples range from $0.570 for Mini 480p to $5.738 for Face 1080p.[2]
  • Longer stories are chained, not generated: the API returns the final frame of a clip on request, and feeding it forward as the next clip's first frame is the documented continuity mechanism[1].
  • Runway does host Seedance 2.0, but its "Extend Video" is a Gen-3 feature, unavailable for Seedance and retiring in July 2026 anyway[3][4].
  • Seedance 2.5 now supports 4–30-second generation on reAPI through doubao-seedance-2.5-face, at 480p, 720p or 1080p.[7][8]

How the duration setting actually behaves

Duration on Seedance 2.0 is a request parameter, an integer from 4 to 15 seconds[1]. Three behaviors worth knowing before you script against it.

First, the default is 5 seconds, and most platform UIs inherit it, which is why "my videos are always 5 seconds" is usually just an untouched setting. Second, reAPI's duration is an integer from 4 to 15, or -1 on doubao-seedance-2.0, -face and -official to let the model choose (Fast and Mini take 4–15 only): an out-of-range value such as 3 or 16 is not clamped, it is rejected with HTTP 400 and code 20003, and no credits are spent. Third, when reference videos are involved, the input budget is separate from output duration: up to 3 reference clips totaling 15 seconds feed in regardless of how long the output runs[1].

Frame budget: at 24fps[1], 15 seconds is 360 frames, and that is the arena where long-generation quality lives or dies; temporal drift compounds per frame, which is exactly why vendors cap length rather than let quality decay advertise itself.

What each extra second costs

Per-second billing makes duration a linear cost dial, and the tier matters far more than the length. On reAPI's August 17 rates,[2] a 15-second clip with no source video runs:

Tier15-second clip
Mini, 480p$0.570
Fast Face, 480p$0.930
Fast Face, 720p$1.980
Face, 720p$2.307
Face, 1080p$5.738

The practical takeaway for anyone budgeting story content: fifteen seconds of Mini costs less than five seconds of Face at 1080p. If your cut allows mixed tiers, spend Face on the hero shots and Mini on connective footage. The live pricing table has all cells current.

Going past 15 seconds today

There is exactly one sanctioned mechanism and one hosted-platform myth to clear up.

The mechanism is last-frame chaining. The API can return a generation's final frame (return_last_frame)[1]; hand that image to the next request as its first frame, keep your reference set identical, and the seam carries composition and lighting across clips. A 60-second sequence is four chained generations plus a crossfade-free edit. The technique, along with the reference discipline that keeps characters stable across the joins, is the core of our character consistency guide.

The myth is "Seedance extend on Runway." Runway does serve Seedance 2.0, including the Fast and Mini tiers, from its Standard plan up[3], but the Extend Video feature people remember belongs to Runway's own Gen-3 models, was never available for third-party models, and is scheduled for retirement at the end of July 2026[4]. On Runway, continuing a Seedance clip means the video-to-video route, which is a restyle, not an extension. Chaining via last frame remains the honest way to lengthen Seedance footage anywhere.

The 30-second route is now live

Seedance 2.5 now exposes 4–30-second generation on reAPI as doubao-seedance-2.5-face.[7][8] It supports 480p, 720p and 1080p (1080p arrived in August 2026), so Seedance 2.0 remains the route only for 4K. A 180-second beta claim is not part of the documented production contract.

Doubling the single-pass length halves the minimum number of seams in narrative work, and segmented prompts can reduce some shot chaining. Quality across the full 30 seconds still needs testing on the actual brief; current capabilities and limits are collected in our Seedance 2.5 status guide.

FAQ

How long can a Seedance 2.0 video be?

4 to 15 seconds per generation, at 24fps, across all tiers; the default is 5 seconds[1]. Longer sequences are made by chaining generations through the returned last frame.

Why are my Seedance videos only 5 seconds?

That is the default duration parameter. Set it explicitly, anywhere from 4 to 15 — or -1 on doubao-seedance-2.0, -face and -official to let the model choose; values outside that range are rejected with HTTP 400 and code 20003, and nothing is charged[1].

Why does Seedance only create 15-second videos?

It is a Seedance 2.0 model-level cap in ByteDance's documentation.[1] Seedance 2.5 is a separate live model with a 30-second ceiling on reAPI.[7]

Does a 15-second clip cost more than a 5-second one?

Exactly 3x at the same tier when neither request includes source video.[2] At current rates, 15 seconds of Mini 480p costs $0.570, below the $1.913 cost of 5 seconds of 1080p Face.

Does Runway have Seedance extend?

No. Runway hosts Seedance 2.0 for generation[3], but Extend Video is a Gen-3-only feature that is being retired in July 2026[4]. Lengthening Seedance footage means last-frame chaining, on any platform.

Will Seedance 2.5 make longer videos?

Yes. The live reAPI route accepts 4–30-second output or automatic duration.[7][8]

Duration is a workflow, not a setting

Seedance 2.0 gives you a 15-second canvas and higher resolution; Seedance 2.5 gives you 30 seconds at 480p, 720p or 1080p. Set duration deliberately, mix models and tiers to protect the budget, and chain last frames only when the story exceeds the selected model's ceiling. Both routes use reAPI's video-generation and task workflow.

References

  1. Volcano Engine / BytePlus (ByteDance). Seedance 2.0 — durations, frame rate, smart duration, reference limits, return_last_frame. Retrieved July 2026 from docs.byteplus.com/en/docs/ModelArk/1520757
  2. reAPI. Seedance 2.0 — model page and live pricing. Retrieved August 17, 2026 from reapi.ai/models/seedance-2-0
  3. Runway. Third-party models on Runway — Seedance 2.0 availability. Retrieved July 2026 from help.runwayml.com/hc/en-us/articles/50488490233363
  4. Runway. Extend Video (Gen-3) — feature scope and retirement notice. Retrieved July 2026 from help.runwayml.com/hc/en-us/articles/30266515017875
  5. reAPI. Seedance 2.5 — live production pricing and duration range. Retrieved August 17, 2026 from reapi.ai/models/seedance-2-5
  6. reAPI. doubao-seedance-2.5-face — model ID, supported resolutions, duration, and billing. Retrieved August 17, 2026 from reapi.ai/docs/seedance-2-5

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