Add subtitles to a video
An SRT file burned into the picture, so the words show on every screen.
Drop files here
or click to choose from your deviceAccepted: MP4, M4V, MOV, SRT, VTT
Up to 3 files per runUp to 150 MB per file5 runs per dayRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Captions on a vertical 1080 × 1920 Reel: an SRT of three lines, burned in at Medium
bread.mp4 is a 10-second vertical clip shot on a phone (1080 × 1920) for Instagram Reels and TikTok, and bread.srt holds three captions. Both are dropped onto the box together. Style: “White with a black outline”, Size: Medium, Position: Bottom.
- The SRT is read block by block: 00:00:00,500 --> 00:00:03,000 “Three ingredients. No stand mixer.”, then 00:00:03,200 --> 00:00:06,800 on two lines.
- Those two lines are “Mix 4 cups flour, 1½ cups water” and “and 2 tsp salt.”. The third, 7 to 10 seconds, is “Let it rest overnight.” in italic tags, which are dropped.
- Medium on a picture 1080 pixels wide means 63-pixel bold letters on 82-pixel lines; a line wider than 972 pixels (90 % of the width) wraps.
- The captions end 134 pixels (7 % of the height) above the bottom edge. The sound is copied as it is.
| Size | Letters on 1080 × 1920 (also from a 4K 2160 × 3840 clip) | Letters on 720 × 1280 |
|---|---|---|
| Small | 49 px | 32 px |
| Medium | 63 px | 42 px |
| Large | 81 px | 54 px |
You download bread-subtitled.mp4, 1080 × 1920, with the captions in the picture, so they show in the Reels and TikTok players and in group chats alike. If the app’s own caption and buttons cover the bottom, choose Top: the text then starts 115 pixels (6 %) below the top edge.
How it works
- Drop the video (MP4 or MOV) and its subtitle file (SRT or VTT) onto the box together.
- No subtitle file yet? Automatic subtitles writes one from the video’s sound, in any of nine languages.
- Choose the style, the size and whether the subtitles sit at the bottom or the top.
- Select Add subtitles and download the MP4.
Frequently asked questions
- Why burn subtitles in instead of adding a subtitle track?
- Because most places a video ends up — Instagram, TikTok, X, LINE, WhatsApp — ignore subtitle tracks. Burned-in subtitles are part of the picture, so they show everywhere, though they can no longer be switched off.
- Do Japanese subtitles work?
- Yes. The text is drawn with the fonts on your device, which include Japanese ones on Windows, macOS, iPhone and Android, and long lines are wrapped to fit the picture.
- How long does it take?
- The picture is decoded and encoded again as H.264 at a high bit rate (up to 1920 pixels on the long side), which takes about as long as the video lasts on a typical computer and needs Chrome, Edge or Safari 16.4 or newer. The sound is copied as it is. That holds for AAC sound, which phones record; another kind (PCM in a camera MOV) is left out, and the result says so.
- What should an SRT file look like?
- A number, a timing line, the text, and a blank line before the next one: “1”, “00:00:00,500 --> 00:00:03,000”, “Three ingredients. No stand mixer.” The numbers are ignored, a full stop instead of the comma works too, and a WebVTT (.vtt) file is read the same way. Styling tags such as italics are removed.
- Are captions the same size on a vertical video?
- Yes. The size is a share of the picture’s short side, so a vertical 1080 × 1920 Reel gets the same 63-pixel letters at Medium as a 1920 × 1080 video, and long lines wrap at 90 % of the width.
- My SRT wasn’t saved as UTF-8. Will accents come out right?
- Yes. A file that isn’t UTF-8 — as older Windows subtitle programs save them — is read as Windows-1252, so é, ñ and curly quotes are drawn correctly.
- Is the video uploaded, and what are the free limits?
- Nothing is uploaded. The free plan takes one video of up to 150 MB with its subtitle file per run, and 5 runs a day. Pro removes these limits.