MP3 to SRT

When an MP3 needs subtitles

Subtitles belong to something you watch, so an audio-only file needs a reason. The usual ones are: a podcast episode put on a video site with a still image or a waveform, a short clip cut into a social video, a lecture recording played over slides, and an audio track you are editing into a film. In all of those the SRT is a separate file that the player or the editor reads next to the media, and viewers can switch it on or off.

Steps

1. Choose the MP3 in the box above. Leave the language on automatic unless the recording is short or mixes languages.
2. Read the transcript against the audio and fix names, terms and numbers.
3. Export SRT from the editor. Each transcript segment becomes one cue with its own times.
4. Check the cues for length and speed with the free subtitle checker, then split any that run too long with the line splitter.
5. Add the .srt to your video editor or upload it to the platform next to the video.

Timing and MP3 quirks

The times in the SRT are measured on the decoded audio, so they match what you hear when the same MP3 is played. Two things can make them look off. MP3 encoders often put a short stretch of silence at the start of the file, usually well under a tenth of a second, which only matters if you need frame-exact sync. And an MP3 saved with a variable bitrate and no proper header can be mis-measured by some players when you jump around in it; if the cues seem to drift in your editor, convert a copy to WAV or M4A with the audio converter and use that in the editor instead. If the whole SRT is a little early or late, the time shifter moves every cue at once.

Reading speed on spoken audio

A transcript follows the speaker, and people talk faster than most viewers can read. Subtitles made straight from speech therefore tend to flash by. The checker above reports which cues exceed a reading speed you choose, and the usual fix is a shorter line or a cue that stays on screen a little longer, which is an editing decision this page does not make for you.

Size and length

Without an account one file can be up to 15 minutes and 25 MB. A free account lifts those per-file limits and keeps your transcripts in a library, so for a longer recording create one instead of cutting the file up. An MP3 at 128 kbit/s is about one megabyte a minute, so the length limit is usually reached before the size limit.