What is CPS in subtitles?

CPS stands for characters per second — the number of characters (including spaces) a viewer must read each second to follow a subtitle. Lower is easier to read. Broadcast standards typically cap CPS at 17; online video often allows up to 20–21 CPS.

What reading speed should subtitles target?

BBC and EBU guidelines recommend ≤17 CPS for broadcast subtitles. Netflix and YouTube allow up to 20 CPS. Subtitles above 21 CPS are considered too fast for most viewers and should be split or trimmed.

How do I convert CPS to WPM?

Multiply CPS by 60 to get characters per minute, then divide by 5 (the average word length in English including a space). So 17 CPS = 1,020 CPM; 1,020 ÷ 5 = 204 WPM.

Should I count spaces in the character count?

Yes. Most subtitle standards (EBU STL, Netflix, BBC) count spaces as characters when calculating CPS because they still require reading time and contribute to line width.

What if my subtitle has two lines?

Count all characters across both lines, including the line break. Some tools ignore the line break character itself; this calculator counts the visible characters + spaces only.

How do I calculate display duration from frame numbers?

Subtract the start frame from the end frame to get the frame count, then divide by the frame rate (e.g. 24, 25, 29.97, or 30 fps). This tool does that calculation automatically when you use the Frames tab.

Subtitle Reading Speed

Enter subtitle text length and display duration to find the minimum reading speed (CPS/WPM) required to follow your subtitles.

Subtitle Parameters

Subtitle Text

Or enter count manually:

Spaces included. Auto-filled when you type text above.

Display Duration

seconds

Enter subtitle details and click Calculate

Characters per Second

CPS

Words per Minute

WPM

Inputs Used

Characters Duration CPS Equivalent WPM

CPS Reference Scale

≤ 17 CPS — Broadcast standard (BBC / EBU)

18 – 20 CPS — Acceptable (Netflix / online video)

> 20 CPS — Too fast; split or shorten subtitle

0 17 20 30+

Maximum Character Budgets

chars at 17 CPS

chars at 20 CPS

chars (current)

Summary

This tool calculates the minimum reading speed a viewer needs to keep up with your subtitles. Enter the number of characters and the display duration (in seconds or frames) to get the required characters per second (CPS) and words per minute (WPM). Industry guidelines recommend staying under 17 CPS for broadcast and 20 CPS for online video.

How it works

Enter the subtitle text or paste it directly to auto-count characters.
Set the display duration in seconds, or enter start/end timecode frames and frame rate to calculate it.
The tool computes characters per second (CPS) and equivalent words per minute (WPM).
A readability rating shows whether the subtitle meets broadcast or online video standards.
Adjust the character count or duration until the rating turns acceptable.

Use cases

Check whether subtitles for a film or TV show meet broadcast reading-speed standards.
Validate auto-generated subtitles from speech-to-text tools before publishing.
Find the maximum character count for a given subtitle slot duration.
Audit SRT files for lines that are too fast for average viewers.
Ensure accessibility compliance for subtitles targeting viewers with reading difficulties.
Optimize online-course captions for different audience reading levels.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu