Kling 4.0 API pricing: what 720p and 1080p video costs per second, with and without a source video
Kling 4.0 API pricing from $0.1134 per second on UnificAlly: Standard vs Pro, with-source-video rates, what 10 s and 30 s videos cost, launch sale.
Kling 4.0 is Kuaishou's fourth-generation video model, released October 15, 2026, and live on UnificAlly from $0.1134 per second at 720p. Every video runs 3 to 30 seconds with two-channel stereo audio on by default, takes up to 15 combined reference images and elements, and can start from text, references, up to 10 keyframes, or a source video. This post is the Kling 4.0 pricing breakdown for developers: the full per-second rate card, what a real video costs at 10 and 30 seconds, how the with-source-video rates work, what the 10% launch sale does to the numbers, and how the rate compares with Kling 3.0 Omni and the other flagship video models on the platform. Parameters and a playground are on the Kling 4.0 API page.
TL;DR: Kling 4.0 costs $0.1134/sec of output in Standard mode (720p) and $0.1701/sec in Pro mode (1080p) on UnificAlly, with stereo audio included in the rate. Transform and video reference mode, where you supply a source video, bill at $0.1359/sec (720p) and $0.2043/sec (1080p) for the length of the source. A 10-second 1080p video costs $1.701; a 30-second one costs $5.103. A 10% launch sale is running on all four rates until October 29, 2026, and the figures on this page already include it. Our pick: Kling 4.0 Pro for anything with dialogue, a cast, or a shot longer than 15 seconds, and Kling 3.0 Omni Standard for cheap drafts and 4K.
How much does the Kling 4.0 API cost?
Kling 4.0 bills per second of output video, and two things set the rate: the mode (Standard at 720p or Pro at 1080p) and whether the request carries a source video. Everything else is included. Reference images, persistent elements, keyframes, multi-shot, the 21:9 ratio, 8,000-token prompts and the stereo audio track do not change the price. The rates below refresh from the live price list on every deploy and show the sale price while the launch sale runs.
| Model | Option | Our rate |
|---|---|---|
| Kling 4.0 Video | mode: std | $0.1134/sec |
| mode: std with source video | $0.1359/sec | |
| mode: pro | $0.1701/sec | |
| mode: pro with source video | $0.2043/sec |
The with-source-video rows apply to transform and video_reference modes. In both, the output runs the length of the source video and is billed per second at the higher rate, so a 12-second source always produces a 12-second bill whatever duration you send. Failed tasks are not billed; you pay for completed videos only. The pricing page lists every Kling model side by side.
Kling 4.0 cost per video: worked examples
The table is the rate; these are the invoices. Each row is one request at the lengths developers actually ask for, with audio on.
| Example request | Cost |
|---|---|
| 5 s, Standard 720p, text-to-video draft | $0.567 |
| 10 s, Standard 720p, product spot from two reference images | $1.134 |
| 10 s, Pro 1080p, the same spot for delivery | $1.701 |
| 15 s, Pro 1080p, four keyframes, one journey | $2.5515 |
| 30 s, Standard 720p, longest single take | $3.402 |
| 30 s, Pro 1080p, longest single take | $5.103 |
| 10 s source video restyled in transform mode, Pro 1080p | $2.043 |
Two things fall out of these numbers. First, the Pro premium is a flat multiple, so the decision between 720p and 1080p is about the destination, not the brief: draft in Standard, deliver in Pro. Second, the 30-second ceiling is the real cost driver. A single 30-second Pro take costs as much as six 5-second drafts, so write and test the prompt at 5 seconds, then run the long version once.
Kling 4.0 cost per month at 100, 1,000 and 10,000 seconds
Monthly spend is seconds of finished video times the per-second rate. The table multiplies the live rates by three volumes; a 10-second ad is 10 seconds, a 30-second take is 30, so 1,000 seconds is roughly 100 short spots or 33 long takes.
| Seconds per month | Standard 720p | Pro 1080p | Standard with source video | Pro with source video |
|---|---|---|---|---|
| 100 | $11.34 | $17.01 | $13.59 | $20.43 |
| 1,000 | $113.40 | $170.10 | $135.90 | $204.30 |
| 10,000 | $1134 | $1701 | $1359 | $2043 |
There is no subscription and the balance does not expire, so a slow month costs only what you generate. A team that drafts 1,000 seconds in Standard and promotes a tenth of it to Pro pays $113.40 plus $17.01, well under 1,000 seconds of Pro.
The Kling 4.0 launch sale
Kuaishou launched Kling 4.0 with a 10% discount on all four rates, and the sale ends on October 29, 2026. The price tokens on this page read the live price list, so they show the discounted rate while the sale runs and switch to the list rate when it ends. If a batch can wait, it cannot wait past that date; if it cannot, the difference on a 1,000-second month is about a tenth of the Standard column above.
Kling 4.0 vs Kling 3.0 Omni pricing: what the higher rate buys
Kling 4.0 costs more per second than Kling 3.0 Omni in both modes, and the gap is the price of the upgrade list: double the single-take ceiling (30 seconds against 15), 15 combined references against 7, a keyframes mode with up to 8 middle frames where Omni takes only a first and last frame, the new 21:9 ratio, stereo audio on by default, and 8,000-token prompts. Omni keeps two things 4.0 does not have yet: a 4K mode, and the lower Standard rate for drafts.
| Kling 3.0 Omni | Kling 4.0 | |
|---|---|---|
| Standard 720p, per second | $0.0756/sec | $0.1134/sec |
| Pro 1080p, per second | $0.1008/sec | $0.1701/sec |
| Pro 1080p with audio, per second | $0.126/sec | $0.1701/sec (included) |
| 4K, per second | $0.378/sec | not available yet |
| Max seconds per video | 15 | 30 |
| References (images + elements) | 7 | 15 |
| Keyframes | first and last | first, up to 8 middle, last |
The audio row is the one to read carefully. Omni charges extra for native audio in Pro mode; Kling 4.0 includes stereo audio in its Pro rate, so for a 1080p video with sound the two models are much closer than the Standard rows suggest. For silent 720p drafts and for 4K delivery, Omni is still the cheaper or only route. For anything with dialogue, a cast of references, or a shot longer than 15 seconds, Kling 4.0 Pro is the pick, and the stereo mix is what you are paying for.
How Kling 4.0 pricing compares with other video models
Per second of 1080p output with audio on UnificAlly today:
| Model | 1080p rate per second | Where it fits |
|---|---|---|
| Kling 4.0 (Pro) | $0.1701/sec | 30 s takes, 15 references, keyframes, source-video editing |
| Vidu Q4 | $0.096/sec | 16 s, 15 image references, no text-to-video |
| HappyHorse 1.1 | $0.126/sec | 3 to 15 s, lip-sync, nine aspect ratios |
| Wan 3.0 | $0.14/sec | 30 s from any input |
| Seedance 2.5 | $0.688/sec | 4 to 30 s, 50 mixed references |
Kling 4.0 Pro sits in the middle of that set: above the budget routes, well under Seedance 2.5 at 1080p, and priced close to Wan 3.0, the other model with a 30-second ceiling. No public leaderboard ranks Kling 4.0 yet (Arena's video boards list Kling 3.0 Pro at #19 on image-to-video as of September 21, 2026), so the quality case rests on Kuaishou's release claims and on the four house videos on the model page: a 21:9 street scene with dialogue and applause in one stereo track, a two-reference product spot with lip sync, a four-keyframe journey, and a claymation restyle of that spot in transform mode. All four were generated in Standard mode, which is the mode we would draft in.
How to call Kling 4.0 at the price you planned
One API key, POST /v1/tasks, and mode set to the tier you priced above. This is a 10-second Pro text-to-video in the new 21:9 ratio, billed at $1.701 when it completes.
curl -X POST https://api.unifically.com/v1/tasks \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"model": "kuaishou/kling-4.0-video",
"input": {
"prompt": "A majestic eagle soaring through mountain peaks at sunset",
"duration": 10,
"mode": "pro",
"aspect_ratio": "21:9"
}
}'
Change mode to std for the 720p draft rate and duration to anything from 3 to 30. Add video_mode: "elements" with image_urls for references, video_mode: "start_end_frame" with start_frame_url, keyframe_urls and end_frame_url for keyframes, or video_mode: "transform" with a video_url for the with-source-video rate. The response returns a task_id; poll GET /v1/tasks/<task_id> or set callback_url. Full field reference: docs.unifically.com/models/video/kling/kling-4.0-video.
Kling 4.0 FAQ
How much does the Kling 4.0 API cost?
On UnificAlly, Kling 4.0 costs $0.1134/sec of output in Standard mode (720p) and $0.1701/sec in Pro mode (1080p), billed per second with stereo audio included. With a source video in transform or video reference mode the rates are $0.1359/sec and $0.2043/sec, for the length of the source. Failed tasks are not billed.
What does a 10-second Kling 4.0 video cost?
$1.134 at 720p or $1.701 at 1080p. A 30-second take, the longest Kling 4.0 makes, costs $3.402 at 720p or $5.103 at 1080p.
Do reference images, keyframes or audio change the Kling 4.0 price?
No. Up to 10 reference images and 7 elements, up to 10 keyframes, multi-shot, the 21:9 ratio and the stereo audio track are all included in the per-second rate. Only the mode (Standard or Pro) and the presence of a source video change what a request costs.
Is there a Kling 4.0 launch sale?
Yes. Kuaishou launched Kling 4.0 with 10% off all four rates until October 29, 2026. The prices on this page follow the live price list, so they show the discounted rate during the sale and the list rate after it ends.
Is Kling 4.0 more expensive than Kling 3.0 Omni?
Per second, yes: Standard is $0.1134/sec against $0.0756/sec on Omni, and Pro is $0.1701/sec against $0.1008/sec. The gap narrows for 1080p with audio, because Omni bills audio as a separate higher rate ($0.126/sec) while Kling 4.0 includes it. Omni remains the only route for 4K.
What is the cheapest way to use the Kling 4.0 API?
Draft at 5 seconds in Standard mode, which costs $0.567 per take, and run the 30-second Pro version once the prompt and references are right. New UnificAlly accounts get a $0.50 signup balance, enough for about 4 seconds of Standard output to test the request shape before adding funds.
What will change this post
We will update the rate table when the launch sale ends on October 29, 2026 and the list rates return, when Kuaishou ships the 4K and 10-bit HDR modes it has announced and they get their own rate, when Kling 4.0 Flash becomes callable through the API, and when Kling 4.0 lands on Arena's video boards with a rank worth citing. Prices on this page refresh from the live price list on every deploy, so the tokens stay current between those updates.
Related reading on Kling 4.0
- Kling 4.0 API: playground, parameters, the four house videos.
- Kling 3.0 Omni API: the 4K route and the cheaper draft rate.
- Kling 2.6 API pricing: the budget Kling with native audio.
- Vidu Q4 API pricing and Seedance 2.5 API pricing: the other 1080p rates in the comparison table.
