Kling 4.0's API is live at 11 to 24 cents a second

Kuaishou's Kling 4.0 API is fully available as of October 28, 2026, and a second of its video sells for 11 to 24 cents depending on the host.

Kling's API notes carry the change under October 28, 2026: "Kling 4.0 API Is Now Fully Available, with Native Video Generation up to 30s." A single run now returns up to 30 seconds, at 720p or 1080p, in 21:9 or an adaptive ratio, across three endpoints: text-to-video, image-to-video, and Omni reference-to-video.

Kling bills the model per second of total duration. With no input video, Kling's rate table works out to $0.157 a second at 720p and $0.235 at 1080p, billed at 1.0 and 1.5 units a second at Kling's published unit price. Supply a reference or source video and the rate falls to $0.094 and $0.141, charged across the input and output duration.

Hosts that resell Kling 4.0 reach those same dollars from credit numbers that look nothing alike.

What a second of Kling 4.0 costs by host

• Kling's own API: $0.157/s at 720p, $0.235/s at 1080p
• Runway API at list: the same figures
• Runway API on the promo running through November 30, 2026: $0.1256/s at 720p, $0.188/s at 1080p
• Luma on Plus plan credits: $0.159/s at 720p, $0.237/s at 1080p

Runway's developer docs list the model as kling_4 at 15.7 credits a second at 720p and 23.5 at 1080p, with a credit sold at $0.01, and a 20% discount through November 30, 2026: 12.56 and 18.8 credits, or $0.1256 and $0.188 a second. The same company's consumer plans page prices Kling 4.0 1080p at 118 credits per 5 seconds, or 89 with a 25% discount through November 30, in credits that cost more per unit than the API's.

Luma bills Kling 4.0 at 53 credits a second at 720p and 79 at 1080p. On the Plus plan, where 10,000 credits cost $30, that works out to $0.159 and $0.237. Pro and Ultra sell credits at $0.00225 and $0.002, so the same 720p second costs $0.119 or $0.106 there.

A third channel prices in Kling account credits instead of dollars. useapi.net, a third-party reseller, bills 10 credits a second at 720p and 15 at 1080p against a creator's own Kling subscription, with 10% off on the Pro, Premier and Ultra+ tiers.

Two details sit under the table. Runway rounds each charge up to the next credit, so a 5-second 720p generation bills 64 credits, or $0.64, rather than the $0.628 the rate implies, and short clips cost more per second than the rate suggests. Kling's release note lists Kling 4.0 at "720p / 1080p / 4K" with 10-bit HDR at 1080p and 4K, while the API announcement says it "supports 720P and 1080P (10-bit 4K coming soon)" and leaves the 4K column of the price table empty. On the API, 1080p is the ceiling today.

A 30-second clip at 1080p, the longest single run the API allows, runs $7.05 at Kling's list rate, $5.64 on Runway's promo, and $7.11 on Luma Plus credits.

Runway's 20% discount runs through November 30, 2026, and its docs say list prices apply from December 1.

Kling 4.0 is callable now at /text-to-video/kling-4.0, /image-to-video/kling-4.0 and /omni-video/kling-4.0 from Kling's developer console, or as kling_4 on Runway's API and on Luma.