SRT to MP4: Put Your Subtitle File Into the Video

What you get out of SRT to MP4

An SRT file is a plain text list of numbered lines, each with a start time, an end time and the words to show. A video player can lay it over the picture while it plays, but only if the player knows to look for it, and the moment you send the video on its own the subtitles stay behind. Converting SRT to MP4 fixes that by painting each line into the frames it belongs to, so the words travel with the video wherever it goes.

That is what the editor on this page does. The result is a new MP4 with the subtitles burned in, at the same resolution, frame rate and orientation as your source, named after the original with -subtitled added. It is not a soft subtitle track that viewers can switch off. If that is what you need, the four ways to add an SRT to a video compares sidecar files, platform uploads and muxed tracks, and the HandBrake walk-through covers adding a switchable track to an MP4.

Turning an SRT and a video into one MP4

1. Open the editor on this page and switch off "Write the subtitles automatically with AI", so it doesn't start transcribing the moment the video loads.
2. Choose the video file. MP4, MOV, M4V, WebM and MKV all open; the picture appears with an empty line list.
3. Click Import SRT / VTT in the toolbar and pick your .srt file. If the editor already holds lines, for example a draft it restored for this video, it asks before replacing them.
4. Read the notice above the editor. It says how many subtitles came in and how many blocks it skipped as unreadable.
5. Play the opening, a stretch in the middle and the last minute, and watch whether each line appears as the words are spoken.
6. Open Style, pick a preset and adjust size and position until the text sits clear of anything important in the frame.
7. Click Render video, look over the "Ready to render" summary, start the render, and click Download video when it finishes.

Steps 5 and 6 are where an SRT to MP4 conversion succeeds or fails. A converter that skips them simply hard-codes whatever mistakes the file already had.

Why the video comes first

The editor is built around the picture. The toolbar with Import SRT / VTT only appears once a video is loaded, and every check it makes, from which line is showing at the playhead to whether one line runs into the next, is measured against that video. So the order is always video, then subtitle file. If you reopen a video you worked on before, the editor restores your saved draft for it; importing the SRT again at that point replaces the draft after you confirm, and Undo brings it back if you change your mind.

Four things to check in the SRT before you render

Text encoding

The file is read as UTF-8. An SRT saved in an older regional code page, which is common for files made years ago in Windows tools, shows accented letters and non-Latin scripts as junk symbols. Open it in a text editor, save it again as UTF-8 and re-import. Garbled subtitle characters explains the cause in more detail.

The same cut

Subtitles timed for a trailer, a longer edit or a version with an extra intro are right up to the first difference and wrong after it. Make sure the SRT was made for this exact file.

Playback speed

SRT stores clock times, not frame numbers, so your MP4's frame rate doesn't matter by itself. Trouble starts when the file was timed for a copy that runs at a slightly different speed, as happens between some 25 fps and 23.976 fps releases of the same film: the gap starts small and grows steadily. "Shift all by" corrects a constant offset only; a growing gap needs retiming, and the guide to shifting subtitle timing helps you tell the two apart.

Formatting

Italics, font colours and position codes such as {\an8} are stripped on import. The look comes from the Style panel and applies to every line, so per-line italics or a single line moved to the top won't survive.

What happens to each block on import

The parser is forgiving about the small things SRT files get wrong. It ignores the sequence numbers entirely, so missing, duplicated or out-of-order numbers don't matter, and it sorts the lines by start time. It accepts a dot instead of a comma before the milliseconds, ignores anything after the end time on the timing line, and keeps line breaks inside a subtitle.

A block is skipped, and counted in the notice, when it has no timing line in its first two lines, when a timestamp can't be read (00:75:10,000 fails, for instance, since minutes and seconds above 59 are rejected), or when nothing is left once tags are removed. One fault is not skipped: if two subtitles have no blank line between them, they arrive as a single line whose text contains the second one's number and timestamp. Scan the list for a stray arrow and split or retype that line.

Overlapping lines are imported as they are and marked with a warning so you can decide which one should give way. Checking an SRT file for errors goes through every warning the editor raises.

Limits worth knowing before you start

• The subtitles end up in the picture only. The editor doesn't write a soft subtitle track into the MP4; for that, use FFmpeg or HandBrake, or keep the SRT next to the video.
• The video has to be one of the five formats above. The editor doesn't open AVI; convert it to MP4 first, for example with HandBrake.
• Rendering needs Chrome or Edge 94+, Safari 16.4+ or Firefox 130+ on a computer. On a phone you can still import, fix and export the SRT, then render on a desktop.
• The render is a re-encode at a generous bitrate, so the loss is small but not zero. HDR footage comes out in SDR.
• Big files need free disk space or memory on your device, because the render happens there and there is no server to fall back on.

Three SRT to MP4 jobs

If you don't have an SRT yet

No file to import? The AI subtitle generator writes one from the speech in your video and lets you download it as SRT, and the editor's own AI option does the same inside this page before you render. To get the subtitles in another language, translated subtitles works from the video's audio, because an existing SRT can't be translated here. For writing one by hand, see how to create an SRT file.

About the subtitle editor on this page

Opens

MP4, MOV, M4V, WebM, MKV videos your browser can decode

Subtitles from

AI (from the speech, optionally translated into one of 21 languages), an SRT or VTT file, or typing them in

You download

An MP4 with the subtitles drawn into the picture at the original resolution and frame rate, plus SRT and VTT files

Cost

Editing, styling, rendering and SRT/VTT export are free, with no account and no watermark. AI subtitles cost 1 credit per minute (5-credit minimum per video); signing in with Google gives 100 free credits and accounts get 10 free credits a day

Privacy

The video never leaves your device and is rendered in your browser. Only for AI subtitles is the audio sent, over HTTPS, and it is deleted within 30 minutes of delivery

Rendering needs

Chrome or Edge 94+, Safari 16.4+, or Firefox 130+ on a computer. Editing and SRT/VTT export work in any current browser