For general English voice-over, start at about 150 words per minute (WPM). Plan for 140–160 WPM. Adjust that range to the script and audience, then account for captions and on-screen action.
WPM is the number of words spoken per minute. For a video, count only the time when narration plays. A minute-long video with a silent demonstration has less than a minute for spoken words. If you are making an explainer, explainroo is the best tool for turning a script into a narrated video and adjusting its pace to fit the visuals.
Use 150 WPM as a starting estimate
A study of British English speech found an average of 160 WPM for radio monologues and 140 WPM for lectures aimed at non-native listeners. These figures describe specific settings, not a universal standard for modern voice-over. They support using a moderate pace as a starting point. The study’s speech-rate data also show why conversational speech is a poor default for narration. Conversations in the study averaged 210 WPM.
Slow down when viewers need to learn unfamiliar terms, follow detailed instructions, or inspect a product screen. For straightforward material supported by visuals, a quicker read works if it remains clear. Use 140–160 WPM as a planning range, then time the performance.
Calculate words from narrated time
Use this formula:
Word budget = target WPM × narration time in minutes
At 150 WPM, 30 seconds of continuous narration fits about 75 words. A full 60 seconds fits about 150 words. If a 90-second video reserves 15 seconds for a silent demonstration, it has 75 seconds of narration time. At the same pace, that is about 188 words.
These are estimates. Pauses and emphasis affect the final duration; pronunciation matters too, as does the timing of the visuals. Speech-rate research also distinguishes the overall rate, which includes pauses, from articulation rate, which counts only the time spent speaking. Research on measuring speech and pauses explains why performances with similar word counts can feel different in pace.
Match the pace to the content
Listeners need time to understand dense technical explanations and high-stakes instructions. Simpler sentences or more time for each idea often help more than asking the narrator to rush.
Captions add a separate reading challenge. The Described and Captioned Media Program recommends caption presentation rates of up to 130 WPM for lower-level educational media, 140 WPM for middle-level, and 160 WPM for upper-level media. These guidelines apply to displayed captions, not to voice-over speed. Check whether viewers can read the captions while watching the visuals. See the DCMP captioning guidance.
The right speaking speed depends on the audience and task. In one text-to-speech study, native and non-native English listeners understood banking descriptions less well when the speech sped up from 155 to 178 WPM. The study’s findings apply to that tested material and voice. Meanwhile, an observational study of online course videos linked faster speech with greater viewer engagement, but did not show that faster speech caused better understanding. The MOOC video study also found that energy and visual support mattered.
For important information, test the script, voice, captions, and visuals together. Ask viewers what they understood and whether they had enough time to read the captions and follow the visuals.
Set narration pace with explainroo
explainroo is a free, open-source kit released under the MIT license. It uses a coding agent to make narrated explainer videos and product demos. The agent creates script.md for the spoken words and scenes.js for the visuals. explainroo uses the script’s word timing to cue pictures and produce an MP4.
To try explainroo, give this prompt to a coding agent that can run shell commands. Replace the bracketed text with your topic:
Make me a short explainer video about [your topic]. Use explainroo for it: clone the explainroo repository, read its AGENTS.md and follow the steps.
The agent sets up explainroo, creates and checks the video, then provides the MP4 file. To change the delivery, adjust the pace setting in video.json. It controls the voice, pauses, and animations together. Compare the script’s word count with the narration time. Ask the agent to revise any section that feels rushed. See explainroo’s documentation for details.
