YouTube auto dub 'speech too fast': measure your pace with Sume

YouTube's help page lists speech that is too fast among the reasons a video can be ineligible for auto dubbing (read 2026-10-02), but it publishes no words-per-minute threshold. You can still measure your own pace before you upload: run video inspect with transcribe: true, divide the transcript's word count by the speaking minutes, and compare quick segments against your other videos. Sume cannot tell you where YouTube's cutoff is.

What YouTube says

The page names the conditions that make a video ineligible, or make a dub fail. Speech rate is one of them, with no number attached.

Measure the pace

Run video inspect with transcribe: true. The probe and stills are unbilled; the transcript is billed per audio minute (the docs list $0.01, confirm in GET /v1/catalog). With segmentation: { mode: "sentence" } you also get sentence segments, which show where the pace changes.

• Count the words in the returned text.
• Divide by the minutes of speech, not the whole runtime, so silence does not hide a fast stretch.
• Compute the same figure for a video you know YouTube dubbed successfully, and use that as your own reference.

Slow the fast stretches

If one segment is far quicker than the rest, re-record it, add a pause, or trim dead air with video trim so that the delivery sounds less rushed. Video trim cuts only; it does not change speed, so it will not slow speech down on its own.

What this does not prove

A normal pace in your measurement is not a guarantee. YouTube's detection method is not published, and the other ineligibility reasons still apply. Upload, then check the Languages tab in YouTube Studio to see whether a dub was created. Creators can publish, unpublish or delete a dub on desktop; a deleted dub can't be republished.