Kling: Kling 4.0 Flash Image to Video API

Kling 4.0 Flash image-to-video: starts from a single first-frame image, 720P up to 20 seconds with sound, at a lower per-second rate than 4.0.

Frequently Asked Questions

Why does submission say my balance is insufficient when it covers one video?

On submission the gateway reserves the **most the request could cost**: without `settings.duration` the model may make a video of up to 20 seconds from the prompt, so 20 seconds is assumed, and attached videos are assumed at the input maximum. On completion you are charged the credits Kling actually deducted and the rest is returned. Setting `settings.duration` makes the reservation match the real cost.

Can I keep the result URLs long-term?

Kling deletes generated videos after **30 days**. If object storage is enabled on this site, the gateway re-hosts the result when the task succeeds (callbacks and the unified task API return the re-hosted URL); otherwise download and keep it yourself.

How long does a task take and how do I get the result?

Video generation is asynchronous and usually takes from tens of seconds to a few minutes. Set `options.callback_url` to get a push on every status change, or poll the query endpoint.

Kling 4.0 Flash or Kling 4.0?

Flash is the lightweight 4.0 with a lower per-second rate (0.6 credits per second without video input, versus 1.0 for 4.0 at 720P), suited to quick drafts, prompt testing and many variations. Choose Kling 4.0 for 1080P, videos longer than 20 seconds (4.0 goes up to 30), middle / last frames, or referencing voices directly in Omni Video.