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SRT subtitle maker: script to caption file
Paste the script of your video and get a timed SRT or VTT caption file, ready to upload. Or convert an SRT file to VTT.
Your script
Your captions
| # | Start | End | Text | CPS |
|---|
Convert SRT to VTT
Already have an SRT file? Choose it or paste it, and download the same captions as VTT for a web player.
Paste your script, set how fast it is spoken, and the tool splits it into caption lines of up to 42 characters, times each one from its word count and lets you download an SRT or VTT file. Upload the file with your video, then check the timing in the platform preview.
Most people watch social video with the sound off, so a film without captions loses its message in the feed. Uploading a caption file is the cleanest way to add them: the platform shows the words over your video, viewers can turn them on or off, and the text can be read by search engines.
An SRT file is a plain text list of numbered captions, each with a start time, an end time and one or two lines of text. VTT is the same idea with a slightly different format, used by web video players. This tool writes both from your script, so you do not have to type the timings by hand.
How the timing is worked out
Each caption stays on screen for as long as it takes to say its words at the speaking rate you set. At 150 words a minute, which is a calm narration pace, a caption of ten words lasts four seconds. The tool keeps every caption between one and seven seconds, so short lines do not flash past and long ones are split.
The CPS column shows how many characters a second each caption asks the viewer to read. Netflix's English subtitle guide allows up to 20 for adult viewers, so rows above that are marked. If a row is marked, shorten the line in your script or slow the speaking rate.
Why 42 characters a line
Netflix's guide sets 42 characters per line and at most two lines, and many teams use the same limits. Short lines are easier to read on a phone and cover less of the picture. If your video is vertical, try 32 to 36 characters, because the frame is narrower.
Writing a script that captions well
Captions are easier to read when each sentence is short and says one thing. Break long sentences in your script before you paste it, and keep product names and numbers on the same line as the words around them. Avoid starting a caption with "and" or "but" where you can, because a caption read on its own should still make sense. If a scene has no speech, leave it out of the script and set the start time of the next line instead.
Check the timing against the real voiceover
This tool estimates timing from the script, so it will not match a recorded voiceover exactly. After you upload the file, play the video in the platform's preview and nudge any caption that comes in early or late. If you have not recorded the voiceover yet, use the voiceover length checker first to make sure the script fits the film.
Captions matter most where video autoplays without sound. Our note on captions for muted product videos explains how to write for them. Every film we make includes captions burned in and a separate subtitle file, from One Film upward.
How to use it
- Paste the script. Paste the words that are spoken in the video. Put each scene on its own line or paragraph.
- Set the speaking rate. Leave 150 words per minute for calm narration, or raise it for a fast read. Set the start time if the voice starts after an intro.
- Check the captions. Read the table. Shorten any line marked as fast to read, or lower the speaking rate.
- Download the file. Download the SRT or VTT file and upload it with your video. Then check the timing in the platform preview.
Frequently asked questions
What is the difference between SRT and VTT?
Both are text files of timed captions. SRT numbers each caption and uses a comma before the milliseconds. VTT starts with a WEBVTT line and uses a full stop. Social platforms commonly accept SRT, and web video players use VTT.
How do I add an SRT file to a LinkedIn video?
When you post a video on LinkedIn, the editor has an option to add a caption file. Choose the SRT file you downloaded here, then publish. The exact menu can change, so look for captions or subtitles in the video settings.
Will the timing match my voiceover exactly?
Not exactly. The timing is estimated from the word count and the speaking rate you set. It is usually close for steady narration. Play the video with the captions and adjust any that come in early or late.
Is my script sent anywhere?
No. The captions are made in your browser and the files are created on your computer. Nothing you paste is sent to us.
Sources
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