AI voiceover generator for videos: script to publish

Script, then voice, then picture. Cut the footage first and you'll spend the afternoon stretching shots or chopping sentences to squeeze the narration in. Lock the voice and the picture lines up on the first pass.

Same workflow for a 40-second Short or an hour-long documentary:

1. 1Write the whole script in a doc, for the ear rather than the page. Tips below.
2. 2Estimate the runtime: about 150 words, or roughly 1,000 characters, per minute. An 8-minute video needs around 1,200 words.
3. 3Paste the text into the generator or upload the file (txt, md, srt, pdf, docx) and pick a voice. Preview it with a line from your own script, not the sample sentence.
4. 4Generate and listen to the result. If you want to change something, change it in the text and generate just that part again.
5. 5Download the MP3 and import it into your editor on its own audio track, starting at zero.
6. 6Cut the footage to the voice: a new idea, a new shot.
7. 7Drop music on a separate track, pull it under the voice and turn on auto-ducking if your editor has it.
8. 8Add captions. A large share of social video is watched with the sound off.
9. 9Export, check the final loudness, and publish. Use the platform's AI disclosure setting when it applies.

The usual reference is about 150 words per minute: the National Center for Voice and Speech puts average American English speech there. Audiobook narration tends to sit near that pace too. Use it to plan, then check it against the actual voice you pick, because voices differ more than scripts do.

Character count is the more precise unit, since that's what any voice generator measures. One thousand characters, spaces included, is a good round number for a minute of audio.

Write for the ear. Viewers can't scroll back and reread, so every sentence has to land the first time.

• Keep sentences under 20-25 words. If one needs two commas and a parenthesis, split it.
• One idea per sentence, with the key point at the end, where the stress naturally falls.
• Ordinary amounts, dates, times and prices read fine on their own. Acronyms and odd symbols are another story: spell them the way you want them said, like "N-A-S-A" versus "NASA", or "three times" instead of "3x".
• Punctuation sets the pace. A period is a pause, a comma is a breath, and a script with no periods gets read in one go.
• Don't read long lists aloud. Past four items, people forget; put them on screen and have the voice name the two that matter.
• Read the script out loud yourself before generating. Wherever you stumble, the AI voice will sound strained too.

The voice sets the tone before the picture does. Choose with your script in front of you: a voice that's perfect for a tutorial can sound flat on an ad.

If your audience knows your voice, clone it: your videos keep sounding like you on days you don't record. For a faceless channel, a library voice skips that step and you can switch voices per series or per language.

The menus differ, the idea doesn't: the MP3 gets its own audio track, starts at zero, and the picture follows it.

PowerPoint can record your own narration from a mic, and for an internal meeting that's often enough. For a deck that needs to sound polished, or one you'll update often, an AI voice saves re-recording: change the text, regenerate that slide's clip, done.

The cleanest setup is one audio clip per slide. "Chain audios" generates up to 100 clips in one go, each named, which suits a deck well.

1. 1On each slide: Insert > Audio > Audio on My PC, and choose that slide's MP3.
2. 2With the audio icon selected, open the Playback tab and set Start to Automatically. Check Hide During Show.
3. 3On the Transitions tab, uncheck On Mouse Click and set After to the length of that clip.
4. 4To turn it into a video: File > Export > Create a Video, choose Use Recorded Timings and Narrations, pick a resolution (up to 4K) and save as MP4.

A common editing rule of thumb: voice peaks between −12 and −6 dB, music around 20 dB lower while someone is talking. Music with vocals or heavy drums needs to sit lower still.

Auto-ducking pulls the music down under the voice and back up in the gaps. Premiere has it in Essential Sound, DaVinci does it with a sidechained compressor, and in CapCut you do it with volume keyframes.

Before you export, measure the integrated loudness of the full mix in LUFS. These are the targets the platforms publish themselves:

An hour-long documentary, a course or an audiobook can be generated in one pass: each audio takes up to 600,000 characters, about 10 hours of speech (7 to 12 depending on how fast the voice is). No splitting the script, and no risk of two halves sounding slightly different.

Chaining clips and the API use purchased credits; the monthly free credits are for generating on the website.

Yes to monetized videos, ads and client work. No to impersonating someone or illegal content.

YouTube asks you to flag realistic content that's generated or meaningfully altered with AI, such as making a real person appear to say something they didn't. Its own list of exceptions includes cloning your own voice for voiceovers or dubs, and using AI for scripts or captions.

Monetization is a separate question. Since July 2025 YouTube calls mass-produced or repetitive uploads "inauthentic content", and that explicitly covers AI videos built from generic templates without the creator's own input. A channel of interchangeable videos is at risk with or without a synthetic voice. What keeps you safe is an original script with your own research and point of view.

TikTok asks you to turn on its AI-generated content label for realistic AI content, and bans misleading synthetic media about real people or events regardless of labeling.

Most of these get fixed by rewriting the script before you generate.

• Pasting a blog post or a PDF as is. It sounds like someone reading a brochure out loud.
• Leaving "1/2" or "Inc." as symbols. They can come out in unexpected ways.
• Choosing a voice from its demo line instead of your own script.
• Music too loud, or music with lyrics under the narration.
• Cutting the picture first and forcing the voice to fit.
• Generating 20 minutes without testing one minute first.
• Cranking expressiveness to the max to sound "more alive": overdoing it makes it sound less natural.
• Skipping captions on social video.