Kling 4.0 and Seedance 2.5 both make clips up to 30 seconds long, both with sound, and both are on the shortlist for creators who want more than a still. Where they differ most for adult work is what happens before a single frame renders: one refused our requests, and the other delivered.
Short answer: for any NSFW work above Mild, pick Seedance 2.5. In our text-to-video tests, Kling 4.0 refused both the Moderate and the Very strong request within about 2.5 seconds, and nothing was rendered or charged. Seedance 2.5 delivered across its image and reference runs, and Seedance 2.5 Spicy delivered the strongest levels from a still. Kling 4.0 is the better pick for general-audience work: it is cheaper per second at 720p and 1080p, takes 21:9 and up to nine keyframes, and always generates stereo sound.
Seedance 2.5 → · Seedance 2.5 Spicy → · Kling 4.0 →
Kling 4.0 went live on SpicyAPI on 16 October 2026 and gained video edit and video extend on 22 October. Our full write-up of its content policy is in Is Kling 4.0 uncensored?, and the model page is at Kling 4.0. This article is the spec and result comparison.
Specs side by side
| Kling 4.0 | Seedance 2.5 | Seedance 2.5 Spicy | |
|---|---|---|---|
| Maker | Kuaishou (Kling) | ByteDance | ByteDance |
| Page label | Filtered | Uncensored | Uncensored |
| Tasks | Text-to-video, image-to-video, reference-to-video, video-edit, video-extend | Text-to-video, image-to-video, reference-to-video, video-extend | Image-to-video, video-extend |
| Clip length | 3 to 30 whole seconds | 4 to 30 seconds | 4 to 30 seconds |
| Resolution | 720p or 1080p | 480p, 720p or 1080p | 480p, 720p or 1080p, plus a 4k tier that is upscaled |
| Aspect ratios | 16:9, 9:16, 1:1, 21:9 | With references: 21:9, 16:9, 4:3, 1:1, 3:4, 9:16, adaptive | Not listed for this task |
| Opening and closing frames | Opening frame, optional closing frame, up to 9 in-between keyframes (8 if you also send a closing frame) | Opening frame plus optional closing frame | Opening frame plus optional closing frame |
| Reference images | Up to 10 (@Image1 and so on) | Up to 30 | Not accepted |
| Reference videos | Up to 5, 30 seconds in total | Up to 10, 2 to 30 seconds each, 30 seconds in total | Not accepted |
| Reference audio | Up to 3 clips of 5 to 30 seconds | Up to 10 clips, 2 to 30 seconds each, 30 seconds in total | Not accepted |
| Sound | Always generated, stereo, no switch | On by default, can be switched off | On by default, can be switched off |
Kling 4.0 is the only one of the three with no switch for sound: it is always generated, in stereo, with no extra charge.
On aspect ratio, a 1080p 21:9 Kling clip came back at 2200 x 940. Seedance's 21:9 is available with its reference inputs.
Price per second
Prices are at the time of writing (22 October 2026). The model page always shows the current price.
| Resolution | Kling 4.0 | Seedance 2.5 | Seedance 2.5 Spicy |
|---|---|---|---|
| 480p | Not offered | $0.1234 per second | $0.216 per second |
| 720p | $0.1884 per second | $0.2773 per second | $0.432 per second |
| 1080p | $0.282 per second | $0.6823 per second | $1.08 per second |
| 4k | Not offered | Not offered | $2.16 per second (upscaled) |
Some worked examples:
- 5 seconds at 720p: Kling 4.0 is $0.942. Seedance 2.5 is $1.39.
- 5 seconds at 480p: only Seedance 2.5 offers this tier, at $0.62.
- Video edit on Kling 4.0: $0.1128 per second at 720p and $0.1692 per second at 1080p.
- Reference-to-video with a reference video on Kling 4.0: the same rates, counted on output seconds plus reference seconds.
Seedance's price is the same with sound on or off. Kling's 1080p rate is well under Seedance's: $0.282 against $0.6823 per second. At 720p the gap is smaller, $0.1884 against $0.2773. Only Seedance goes down to 480p.
Refused and failed Kling requests are not charged, and the refusal comes back in seconds.
Kling 4.0: where it wins
Kling 4.0 is built for shots that need a planned move. Its keyframes are the feature to test first: an opening frame, an optional closing frame and up to nine in-between frames. In our three-frame test the clip passed through all three poses in order.
Three things to plan around:
- Cuts. Kling adds camera cuts you did not ask for. Write "one continuous shot, no cuts" in the prompt, and check the first render.
- Small lighting cues. It can miss them. If a light change matters to the scene, make it the main event of the prompt rather than a side detail.
- Speed. Three to five second clips took one to four minutes in our runs.
Video edit and extend came to Kling 4.0 on 22 October. For launch details, see Kling 4.0 release date and API.
The NSFW test
We ran a content test on 16 October 2026, text-to-video only:
| Model | Task | Level | Result |
|---|---|---|---|
| Kling 4.0 | Text-to-video | Moderate | Refused after about 2.5 seconds: "Content flagged as potentially sensitive" |
| Kling 4.0 | Text-to-video | Very strong | Refused after about 2.5 seconds, same message |
| Kling 4.0 | Text-to-video | Mild, Strong, Maximum | Not tested |
| Kling 4.0 | Image-to-video, reference-to-video | Any | Not content-tested |
| Seedance 2.5 | Image-to-video | L1 / L2 / L3 / L4 / L5 | 3 of 3 / 3 of 3 / 2 of 2 / 3 of 3 / not run |
| Seedance 2.5 | Reference-to-video | L1 / L2 / L3 / L4 / L5 | 3 of 3 / 3 of 3 / 2 of 2 / 3 of 3 / not run |
| Seedance 2.5 Spicy | Image-to-video | L1 / L2 / L3 / L4 / L5 | 3 of 3 / 2 of 3 (1 softened) / 3 of 3 / 3 of 3 / 3 of 3 for restraint and 3 of 3 for cinematic gore |
Two notes on reading this table.
First, the ladders differ. Kling's Moderate and Very strong results sit on the October five-step ladder: Mild, Moderate, Strong, Very strong, Maximum. Seedance's results sit on the September ladder: L1 suggestive, L2 mature themes, L3 strong, L4 an intimate scene between two adults, L5 extreme (restraint or cinematic gore). Both run from suggestive to extreme in five steps, but they use different prompt sets and were run on different dates. Treat the side-by-side as a strong pointer, not a lab comparison, and do not read Moderate as L2 or Very strong as L3.
Second, the Kling sample is small. We sent two requests to 4.0 and both were refused before any frame rendered. That is enough to say Kling 4.0 refuses higher levels from text, but we did not test its image-to-video route for content, so we cannot say how it handles a still.
On Kling 3.0 earlier, Mild rendered and every Moderate and higher request was refused. Kling checked the prompt, the uploads and the finished clip. We have no evidence that 4.0 behaves differently, but the 4.0 results above are what we measured.
Base Seedance 2.5 was tested on 24 September; Seedance 2.5 Spicy on 25 September, from a still at 480p and 4 seconds. A published Spicy example:
Seedance 2.5: where it wins
Seedance 2.5 takes far more input. Its reference task accepts up to 30 images, 10 audio clips and 10 video clips, against Kling 4.0's 10 images, 3 audio clips and 5 videos. If your shot needs a cast of several people, a set, outfits and a camera move copied from a clip, Seedance is the one that fits.
It also takes a text-only start, which Seedance 2.5 Spicy does not. Seedance 2.5 Spicy is an image-to-video build with the 4k tier and no reference inputs.
For the prompting side of Seedance 2.5, read Seedance 2.5 NSFW prompt guide. For how Spicy differs from base Seedance, see Seedance 2.5 vs 2.5 Spicy.
A workflow that uses both
A practical split: draft the framing in Seedance at 480p, the lowest tier either model offers, at $0.1234 per second. Once the shot works, move the SFW trailer shots that need 21:9 or a planned keyframe path to Kling 4.0 at 720p or 1080p. Keep the adult content in the Seedance branch.
Which one should you pick?
- Strong or intimate work from a still: Seedance 2.5 Spicy. It delivered at the strongest levels we ran.
- Strong or intimate work with references or text-only starts: Seedance 2.5. It takes 30 images, 10 videos and 10 audio clips.
- Cheap draft at 480p: Seedance 2.5, the only option at that resolution.
- General-audience trailers, 21:9 shots or planned keyframes: Kling 4.0. Its 1080p rate is well below Seedance's.
- Always-on stereo sound with no switch: Kling 4.0.
- Edit or extend an existing clip on a budget at 720p: Kling 4.0 at $0.1128 per second for video edit.
Adults only, in every prompt and upload. Do not use a real person's likeness without their consent, and you are responsible for what you generate.
Questions people ask
Is Kling 4.0 better than Seedance 2.5? For general-audience work, Kling 4.0 has the better price at 720p and 1080p, 21:9, keyframes and always-on sound. For NSFW work above Mild, Seedance 2.5 is the one that delivered in our tests.
Can Kling 4.0 do NSFW? Not from text at the Moderate and Very strong levels we tested. It refused both before rendering. We have not tested its image-to-video route for content.
Which is cheaper per second? Kling 4.0 at 720p ($0.1884 per second) and 1080p ($0.282 per second). Seedance 2.5 is cheaper only at 480p ($0.1234 per second).
Do you pay for a refused Kling request? No. Refused and failed requests are not charged. Our refusals came back in about 2.5 seconds with nothing rendered.
