What Is an SRT File?

An SRT file, part by part

Open any SRT in a text editor and you see the same four-part pattern repeated for every subtitle, called a cue:

1

The cue number, counting up from 1

00:00:03,500 --> 00:00:06,250

Start and end time as hours:minutes:seconds,milliseconds, with a comma before the milliseconds and an arrow between the two times

Welcome back to the channel.

The subtitle text, on one or two lines

Blank line

Marks the end of the cue; the next number starts a new one

That is the whole format. There is no header, no styling section and no positioning, which is why almost every player and platform can read it. Some players honour simple tags such as <i> for italics, but many ignore them. Everything else about how subtitles look, from font to position, is decided by the player or editor.

Three ways to make an SRT

1. By hand: open Notepad on Windows or TextEdit on a Mac (choose Format > Make Plain Text first), type cues in the pattern above, and save with the .srt extension and UTF-8 encoding. Watch for the .srt.txt trap: if your system hides file extensions, "subtitles.srt" may really be "subtitles.srt.txt", which players won't load.
2. From a script with no audio: if you have the words but not the timing, a subtitle editor such as Subtitle Edit or Aegisub lets you set each cue's start and end while playing the video. mydubly can't align an existing script to audio; it only makes subtitles from speech.
3. From the video or audio itself: upload the file, and the speech is transcribed and timed into an SRT, in the spoken language or translated into another supported language, along with a VTT and a timestamped transcript. Use the SRT generator for video or audio to SRT for recordings; files can run to 2 hours and cost 1 credit per minute.

The SRT file next to your drone footage

If you copied clips off a DJI drone and found a file with the same name ending in .srt, it isn't dialogue. With the Video Captions setting switched on, DJI drones write flight data into an SRT beside each clip: one cue per frame or time slice, carrying GPS position, altitude and camera settings such as ISO and shutter speed. Load it in a player and those numbers appear over the video. It needs no transcription, and uploading it to YouTube as captions would show telemetry to viewers. Keep it with the clip if you want flight data for a map or overlay tool; delete it or leave it out when you need real subtitles, and make those from the speech instead.

Opening an SRT on each device

Windows

Right-click → Open with → Notepad to read or edit it; to watch it, give it the same name as the video and open the video in VLC

Mac

TextEdit opens it as text; VLC or IINA show it over the video when the names match

iPhone and Android

VLC and MX Player load an SRT with the same name as the video, or let you pick one from the subtitle menu

Editors

Premiere Pro, DaVinci Resolve, Final Cut Pro and CapCut desktop import SRTs as caption tracks; see the DaVinci Resolve and CapCut guides

YouTube

YouTube Studio → Subtitles → choose the language → Upload file → With timing

If the text shows as strange symbols, the file isn't UTF-8. Subtitles showing strange characters explains how to re-save it.

Checking an SRT before you upload it

1. Cue numbers run in order with no gaps or repeats.
2. Every time uses a comma before the milliseconds (00:00:06,250), not a full stop.
3. Each end time is after its start time, and no cue starts before the previous one ends.
4. Exactly one blank line separates cues; extra blank lines inside a cue break some editors.
5. The file is saved as UTF-8, which matters for accented letters and essential for Hindi, Arabic, Chinese or Japanese.

SRT file not working covers the errors that cause most failed uploads.

How long a subtitle line should be

A widely used guideline is 42 characters per line and two lines per cue at most, the limit Netflix sets for English. Reading speed matters as much: a cue that holds a lot of text for a second disappears before anyone can read it. Generated SRTs follow the rhythm of speech, so fast talkers produce long cues; split those in a subtitle editor. Subtitle timing guidelines gives practical numbers.

SRT or VTT?

WebVTT is SRT's web cousin: it adds a WEBVTT header, uses a full stop before the milliseconds, and supports positioning and styling. Most platforms accept SRT; HTML5 video players on websites need VTT. SRT vs VTT compares them in detail, and every mydubly job returns both, so you don't have to convert.

Using the tool on this page

• The spoken language is detected automatically; you select the output language — the spoken language itself for an untranslated transcript, or another language for a translation. Files can be up to 2 hours long.
• Only the audio is sent for processing — the video stays on your device — and audio and text are deleted within 30 minutes of delivery (how files are protected).
• You can download a timestamped transcript, subtitles (SRT and VTT) and plain text. Every output, step and limit is explained on the subtitle generator page.