Pay as you go AI video generator: API or subscription?

A pay-as-you-go AI video generator charges for each clip you make at a published rate, such as a price per second of output, so the bill follows what you generate and a month without clips adds no usage charges. A subscription sells a monthly credit allowance instead, and unused credits can reset: on Runway's Standard and Pro plans, monthly credits don't roll over.

The Runway examples come from its plans and API pricing pages, read 2026-09-28; Sume's come from Sume pricing, its Video generation docs and its billing code.

What's the difference between API and subscription pricing?

A subscription front-loads the cost: you pay for the allowance whether or not you use it, and the rollover rules decide what happens to the rest. Pay-per-use prices each generation, so the cost scales with output. Runway sells both: plans with a monthly credit allotment, and a developer API that sells credits at $0.01 each.

How do I compare the two for my volume?

Multiply the seconds you expect to generate each month by the per-second rate, then compare that with the plan price and how much of its allowance you would really use. Count every take, not only the ones you keep. For example, 20 ten-second clips at 720p on Sume's wan-3.0 reserve $1.25 each, $25.00 a month before the agent fee; in a month you make none, that line is $0.

A subscription makes the most sense when you use most of its allowance every month; pay-per-use follows output that comes in bursts. How much does AI video cost per second through an API? lists per-second rates to plug in.

Can I generate AI video without a subscription?

It depends on the vendor. Runway's Free plan includes 125 one-time credits, and its developer API sells credits for a project in its developer portal. Sume is not a no-subscription option: its pricing page lists video generation with the paid plans, so you pay a plan and then usage.

How does Sume combine a plan with pay-per-use?

The plan (Free $0, Pro $40 / month, Startup $120 / month, Scale $400 / month) sets features and how many jobs run at once; each generation is then billed from one prepaid US-dollar balance at the model's published rate, plus a 5.5% agent fee by default. How Sume pricing works covers the plans in full.

• Top-ups: on-demand purchases from $10 to $1,000, made in the dashboard. In current code they fund team wallets only; the public API has no top-up endpoint.
• Concurrency comes from the plan only; a top-up does not raise it.
• Each job reserves its cost when you submit it, and a failed job's reserve is refunded.
• Enterprise adds invoice or purchase-order billing and custom volume pricing.