AI Video Services Compared: Choose by Workflow, Credits and Monthly Workload

Start with the deliverable, not a plan name. Decide whether you need stock-led editing, an avatar presenter or a short generated scene. InVideo is best framed as a script-to-video workflow; HeyGen and Synthesia as avatar workflows; Runway as a model-driven generator for short clips. They are not interchangeable, so a single ‘best AI video tool’ ranking would hide the decision.

This editorial matrix was checked on September 8, 2026. It does not claim hands-on testing, a universal quality winner or identical regional availability. Plan limits and models change; open the live provider page before paying.

Four workflows that should not be mixed

If a project includes two jobs, budget two rows. An avatar lesson and a cinematic transition should not be forced into one fake “minutes” number.

Why credits are not comparable

InVideo publishes rates for finished minutes in Basic, Pro and Ultra Autopilot, while Agents & Models use model- and second-based prices. Runway charges credits for image, video and audio generation and varies the rate by model, duration and resolution. HeyGen uses credits for avatars, translation and assets. Synthesia’s self-serve documentation describes a separate credit system where operations can consume credits in addition to minutes.

So “ten minutes included” is not a common unit. It could mean ten avatar minutes, several short generations with retries, or a limit for one feature only. Record the unit and the feature beside every number.

A reproducible workload matrix

Use three fixed briefs before comparing platforms: a 60-second explainer with captions, a 60-second avatar lesson in one language, and one five-second generated insert. For every row record the plan, model, unit, free access, watermark, export format and commercial-use terms. Keep retries as an unknown unless you have your own log.

InVideo: script-to-video with a credit ledger

InVideo’s help pages separate AI from Studio. On the InVideo help page updated September 8, 2026, Autopilot lists Basic at 20 credits per minute (stock media only), Pro at 800 and Ultra at 1,600; a library Human or Pro actor adds 200 credits per minute. These figures apply to that mode and do not replace Agents & Models pricing. Eight 45-second Pro clips therefore produce 8 × 0.75 × 800 = 4,800 credits before retries.

This is useful for a mixed slate where most explainers use stock media and only a few scenes require generation. A Studio-labelled offer is not automatically an AI offer because the products have separate subscriptions.

HeyGen: minute totals depend on the engine

HeyGen’s credit documentation lists different rates for Avatar III, IV and V, plus separate costs for translation, Video Agent and assets. Two videos with the same duration may therefore use different credit amounts. For a training brief, record whether you need a standard avatar, lip-synced translation or additional generated assets.

HeyGen also documents consent and avatar-use requirements. Do not upload another person’s likeness or voice without permission, and do not present a synthetic presenter as a real person.

Synthesia: repeatable presenters and team controls

Synthesia describes self-serve and Enterprise plans. Its help centre gives an example in which one minute of video can consume 120 credits, but that example is not a universal rate for every feature. Record the avatar, template, editors and workspace limits next to the minute count.

This makes the service relevant when repeatable presenters, brand templates and team review matter. It is not evidence that the tool is better for a cinematic advertisement or a generated action shot.

Runway: budget seconds, not minutes

Runway states that credits are spent on image, video and audio generation and that each model has its own rate. Its published example for Gen-4.5 is 12 credits per generated second, so a five-second and a ten-second clip have different totals. The Free plan includes a one-time credit deposit, while top-ups may be unavailable to free users.

For a production budget, count the seconds that survive review, then keep a separate retry row. Do not combine a generated bumper with avatar minutes or script-to-video minutes.

Decision rules

Pre-purchase checklist

• Write the finished deliverable and duration.
• Separate editing, avatar, generative shots, translation and assets.
• Record the billing unit and source date.
• Check free access, watermark, export and commercial-use terms.
• Confirm reset, rollover and top-up rules.
• Do not claim speed, quality or savings without a comparable test.

InVideo

If your workload is script-led editing with captions, the InVideo card is a possible starting point for checking the current offer. Match AI versus Studio, then verify the exact product and region at the provider. A card does not guarantee every plan or payment route.

AI assisted research and drafting used official provider documentation. Assignment of a responsible editor does not claim a personal product test or personal proofreading. No personal product test is claimed and no saving is promised.