Give the task its own pace

Silent reading can skip backward or scan a familiar phrase. Narration has breathing, emphasis, pronunciation and pauses that must be heard. A script calculator becomes useful when it keeps pace and added pause time visible rather than returning one unexplained number.

The initial narration setting is 140 words per minute; silent reading starts at 240. These are editable working settings. They are not promises about your voice or every language. Korean uses the same starting numbers, which come from English reading and speaking guidance rather than Korean research.

One original sample, three estimates

A good video starts before the camera turns on. Write one clear idea, then read your script out loud. Listen for the sentences that make you stop for breath. Shorten them. Leave room for a pause after an important point. Your final running time depends on your delivery, not only on the number of words on the page.

This sample contains 58 whitespace word units. The table is a calculation, not a recording of a person reading.

Working rateWithout pausesWith 15% extra time
110 words/min31.6 s36.4 s
140 words/min24.9 s28.6 s
170 words/min20.5 s23.5 s
Seconds = units ÷ units per minute × 60 × (1 + pause allowance / 100)

The allowance is extra time

A 15% allowance adds fifteen percent to the no-pause estimate. It does not mean that exactly fifteen percent of the final runtime is silent. For a 600-word English script at 140 words per minute, the no-pause time is about 4:17; adding 15% gives about 4:56.

If your calibrated rate was measured with the pauses you intend to use, those pauses are already in the rate. Start with 0% extra time to avoid counting them twice.

On-screen text needs reading time too

Titles, captions and quoted text are read silently while the video keeps playing. At the tool’s average silent rate of 240 words per minute, reading a line once takes:

On-screen textOnce at 240 words/min
6 words1.5 s
12 words3.0 s
20 words5.0 s
30 words7.5 s

These assume an average reader. At the tool’s slow setting of 150 words per minute the same lines take about 60% longer. A viewer also has to notice the text first, and lines that compete with narration or busy footage are harder to follow. If every word matters, keep the line on screen longer or say it aloud as well.

Use the estimate while editing

  1. Count the spoken script, excluding scene labels that you will not read.
  2. Read a representative section with your real delivery and calibrate the rate.
  3. Add screen-only sequences or intentional silence separately.
  4. Once a recording exists, use the measured recording length.

Brysbaert’s 2019 meta-analysis reports an English silent non-fiction average near 238 words per minute. It does not establish a Korean eojeol rate or your narration speed.

Evidence & sources

Original worked examples; timing values are calculations unless you measure your own delivery. Read the method.