How to Add Subtitles to a Video on iPhone

The fastest way to add subtitles to a video on iPhone is to transcribe the audio, turn the transcript into word-by-word captions, and burn them into the export, no typing, no manual timing. Here's the real workflow, and where the iPhone's own transcription tools stop short.

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Add subtitles to a video on iPhone with a transcript, not a keyboard

There's no built-in subtitle button in Photos. What the iPhone does have is transcription: apps that turn spoken words into text. The trick is treating that transcript as the raw material. Every subtitle is a transcript with timing attached, one word at a time.

That's a meaningfully different job than typing captions by hand, and it's the only way word-by-word ("karaoke") subtitles are practical for anything longer than a few seconds. Typed captions also tend to drift out of sync the moment you trim or reorder a clip, because nothing connects the words on screen to the audio underneath them. A transcript-driven subtitle keeps that link by construction.

What the iPhone transcribes on its own, and what it doesn't

Voice Memos and Notes can both transcribe speech you record directly inside those apps, on iPhone 12 or later, in English (all variants), Spanish, Portuguese, Italian, French, German, Japanese, Korean, and Simplified or Traditional Chinese. Live Captions works differently again: it transcribes spoken audio live, in any app, on iPhone 11 or later, but it's a real-time overlay on the screen, not a file you can save or attach to a clip afterward.

All three are genuinely useful, and none of them solve this problem. Voice Memos and Notes transcribe audio captured inside those apps, not a video file already sitting in your camera roll. Live Captions never produces a saved transcript at all. So even on a supported iPhone, in a supported language, there's no menu path from "video in Photos" to "captions in that video". The transcript and the footage stay two separate things unless something stitches them back together with timing intact.

Automatic subtitles on iPhone, word by word

This is exactly the gap Montaj closes. It transcribes your clip's audio on your device, then generates word-by-word karaoke subtitles from that transcript automatically, no typing, no manual sync. Each word carries its own timestamp, so tapping into the transcript to fix a misspelled name or a mistranscribed word moves only that word's text; the timing underneath it stays locked to the audio instead of needing a manual re-sync.

Export runs at 1080x1920 in HEVC (.mp4), with no watermark. Once you've added subtitles to a video on iPhone this way, the captions are burned into the image for good. They show up the same way on every platform, whether or not the viewer has captions turned on.