Add Subtitles to MP4
Put SRT, VTT or typed subtitles on an MP4 and download a new MP4.
Tested up to a 20-minute 1080p video (1.2 GB) in desktop Chrome. Processing takes about half the video's length for 1080p. Phones: keep to short clips.
Add a video
How to add Subtitles to MP4
- Choose the MP4 file.
- Add an SRT/VTT file or type subtitles in the editor.
- Pick the style and press Burn subtitles.
- Download the new MP4.
Put subtitles on an MP4 so they show on every device. Choose the MP4, add an SRT/VTT file or type the text, and download a new MP4 with the subtitles burned in.
The output is still an MP4
The video is re-encoded as H.264 with the subtitles drawn in, and the original audio is copied unchanged when the MP4 already uses AAC or MP3. The file plays on iPhone, Android, Windows, Mac, smart TVs and every social platform.
Re-encoding is required for burned-in subtitles; there is no way to add pixels to a video without it. The encoder uses x264 at CRF 23, a common default for good visual quality.
Tested limits
Measured in desktop Chrome on a recent Mac: a 20-minute 1080p video (1.2 GB) worked and took about 10 minutes; 1080p runs at roughly 2× real time and 720p about 4×. 4K works but is slow (a 30-second 4K clip took under 3 minutes). Phones have much less memory than computers: short clips of a few minutes are fine, long or 4K videos may fail. Files above 2 GB are not accepted.
- Chrome desktop (Mac)1080p, 20 min, 1.2 GB≈ 0.5× video length (1080p)
- Chrome desktop (Mac)720p, 10 min, 306 MB≈ 0.25× video length
- Chrome desktop (Mac)4K, 30 s, 132 MB≈ 5× video length
- Phone video (HEVC, vertical)1080×1920, 9 s, 19 MB16 s
FAQ
Is my video uploaded anywhere?
No. The video is processed by ffmpeg compiled to WebAssembly, running inside your browser tab. The file is never sent to a server, so it stays private and there is no upload wait. The only downloads are the page itself and the video engine (about 9 MB compressed, from the jsDelivr CDN).
Does the site use analytics or cookies?
Yes, basic usage analytics through Google Analytics 4. It records page views and anonymous steps, such as which style preset was chosen, ranges like video resolution, and whether a burn succeeded. It never receives your video, your subtitle text or any file name. The site is set up so that analytics cookies are not set for visitors in the European Economic Area, the United Kingdom and Switzerland. Elsewhere, Google Analytics may set cookies.
Is there a watermark or a sign-up?
No watermark, no account, no email. The MP4 you download contains your video and your subtitles, nothing else.
How big can the video be?
Measured in desktop Chrome on a recent Mac: a 20-minute 1080p video (1.2 GB) worked and took about 10 minutes; 1080p runs at roughly 2× real time and 720p about 4×. 4K works but is slow (a 30-second 4K clip took under 3 minutes). Phones have much less memory than computers: short clips of a few minutes are fine, long or 4K videos may fail. Files above 2 GB are not accepted.
Which subtitle and video formats work?
Subtitles: SRT (.srt) and WebVTT (.vtt). You can also type subtitles directly on the page. Video: MP4 and MOV were tested, including H.264 and HEVC phone recordings; WebM and MKV are accepted too. The result is always an H.264 MP4 with AAC or the original audio, the format iPhone, Android, Instagram, TikTok and YouTube all accept.
Does it create subtitles automatically?
No. This tool burns subtitles you already have (an SRT or VTT file) or subtitles you type in. It does not listen to your audio. If you need a transcript first, export an SRT from your editor or captioning service and bring it here.