Soft subtitles — an SRT sidecar, a YouTube caption track, an MKV subtitle stream — are separate data the player renders on top of the video. They're editable, toggleable and searchable, which makes them the right choice for YouTube uploads, streaming platforms and anything where viewers might want another language. But they only work when the player bothers to load them, and most social feeds don't. Burned-in captions are pixels. They survive every platform, every re-upload, every screen recording and every messaging app that strips metadata — the reason creators burn captions into Reels, TikToks and Shorts rather than trusting platform auto-captions, and the reason it matters that so much social video is watched with the sound off. Our free Subtitle Burner takes your finished SRT or VTT file and your MP4, lets you style the captions and preview them live, then burns them permanently into the video — all in your browser, free, with no watermark. This guide explains how to burn subtitles into a video with it, when burned-in captions are the right call and when they aren't, and the mistakes that make a burned caption unreadable or unfixable.
Step one: load video and subtitles. Drop in your MP4 (WebM also plays in your browser) and a finished SRT or VTT file. The preview plays your footage with captions overlaid exactly as they'll be burned — what you see is what the export will contain. Step two: style the captions. Pick the size (6% of video height by default), position (top or bottom), text colour, font (Sans, Serif or Mono) and background: Outline is the classic broadcast look, Box is a semi-transparent background that guarantees readability over bright footage, and None leaves the text bare. The classic white-with-black-outline works everywhere; the box survives the brightest footage. Step three: export in real time. Click export and the video plays through while every frame is captured with captions drawn on. Download the WebM — captions permanently baked in. Keep the tab focused until it finishes.
The choice is about where the video will be watched. Soft subtitles are the right call for YouTube uploads, streaming platforms, and anything where viewers might want another language or the option to switch captions off — they are editable, toggleable and searchable. Burned-in captions are the right call for social feeds, messaging apps, screen recordings and GIFs, where no subtitle track survives the journey. GIFs are the extreme case — they have no caption track at all — so if a captioned clip is headed for GIF duty, burn first, then convert. The trade-off is permanence: you can't fix a typo without re-exporting, and viewers can't turn the captions off. So the workflow that avoids regret is simple — finalise your timing and text first, then burn. Our Subtitle Editor exists for exactly that step: it creates and fixes subtitle timing and produces the SRT/VTT files the burner takes as input. Use the editor first to perfect timing, then the burner to bake the captions in. And if the clip is headed for GIF duty afterwards, our Video to GIF tool converts the captioned video into a looping GIF with the captions already part of the picture.
There is no magic "instant" burn, and any tool that promises one is hiding the work. Real caption burning is a re-encode — each frame must be decoded, drawn on, and re-compressed — and doing it in a browser means real time: your video plays through once while the frames are captured. Burning takes roughly the video's duration on a typical laptop — a 3-minute clip takes about 3 minutes, plus a few seconds to assemble the file. Longer videos and higher resolutions scale linearly. Paid desktop encoders do the same work faster with hardware acceleration; what you get here instead is zero cost, zero upload of your footage, and styling control that free online burners usually lock behind a subscription. Keep the tab focused during export for the fastest result, and for videos over ten minutes consider splitting into parts first. The export is WebM (VP9/VP8 video with Opus audio), which keeps quality high at small sizes and plays in all modern browsers; it uploads fine to YouTube, X and most platforms. If you need MP4 specifically, free converters like HandBrake or CloudConvert can remux it losslessly in seconds.
Burning before the timing is final. Burned subtitles are permanent — you cannot turn them off later, so proofread the SRT first and fix every timing error in the editor before you burn. A typo in a burned caption costs a full re-export. Using the None background over bright footage. Bare white text vanishes against a bright sky or a white wall; the outline or the semi-transparent box exists for exactly that case. Captions too small. The default 6% of video height is sized to stay readable on a phone held at arm's length; shrinking it for aesthetics makes it unreadable where the video will actually be watched. Burning a vertical video as if it were landscape. The canvas matches your source resolution, so 1080 × 1920 Shorts and Reels keep their format, and caption size is relative — but check the preview, because a caption that fits a 16:9 frame can crowd a 9:16 one. Letting the tab lose focus mid-export. The export plays the video through in real time; backgrounding the tab slows or stalls the capture. Burning when soft subtitles would do. For a YouTube upload, a toggleable caption track serves viewers better — burn only when the platform strips subtitle tracks, which is most social feeds. Forgetting the source must be MP4 (H.264). The browser has to decode the source video, and H.264 MP4 is the format it handles; other codecs may not load at all.
The honest limits are three. First, burned subtitles are permanent — you cannot turn them off later, so proofread the SRT first. Second, styling is limited to the built-in options (font, size, position, background); fancy karaoke effects need a desktop editor. Third, the source video must be MP4 (H.264) for the browser to decode it, and the export is WebM rather than MP4 — browsers can encode WebM natively without plugins or uploads, and WebM plays everywhere modern, but if a destination insists on MP4, remux it afterwards. Within those limits, the tool does one job completely: it takes a finished subtitle file and a video and returns a captioned video that shows its words on every device and platform, with no upload and no watermark. Captions are one half of a polished video; sound is the other. If the audio drifts out of sync, fix it first with our Audio Sync Fix tool before you burn anything in — a caption burned onto out-of-sync audio is doubly wrong. The companion guides are our SRT subtitle editing guide, for perfecting timing before you burn, our video-to-GIF guide, for turning a captioned clip into a shareable GIF, and our audio sync guide, for matching lips to words before the captions go on.
Perfect the timing before you burn — cues 1 to 7 seconds, lines under 42 characters.
Turn a captioned clip into a looping GIF — 8 fps, 320 px, small file.
Match lips to words before the captions go on — 50 ms steps, A/B test, export.