Add Subtitles to Vertical Video

Why a tall frame holds less text

The editor sets text size as a share of the frame's shorter side. On a 1920×1080 landscape clip that side is the height; on a 1080×1920 portrait clip it's the width, also 1080 pixels. The same size setting therefore gives exactly the same letters in both clips, but the portrait frame is only a little over half as wide. A line that sits comfortably across a landscape frame has to wrap in a portrait one.

This is easy to miss with AI subtitles. They come back as short live-style lines of about 32 characters, which fit on a single row in landscape. At the Social Media preset's size in a 9:16 frame, a line of that length usually wraps onto two rows and occasionally three. You have a few ways to handle it:

• Accept two short rows. That's normal for vertical video, and the box keeps them together.
• Lower the size a step. Small changes make a visible difference in a narrow frame.
• Split long subtitles at the playhead so each piece fits on one or two rows; splitting and merging subtitles shows the workflow.
• Leave UPPERCASE off unless you want the look; capitals take more width.

The line list's warnings count characters and the line breaks you type, not the rows that wrapping creates in a narrow frame, so a subtitle can wrap to three rows without any warning. Judge wrapping by eye on the preview.

The margins the guide draws

Tick "Show safe area" under Position in Style. The editor works out the clip's shape, labels it, and draws a dashed rectangle inside the frame. The narrower the frame, the bigger the margins, and the bottom is always the deepest:

9:16 and taller

8 per cent of the width at each side, 12 per cent of the height at the top, 16 per cent at the bottom.

4:5

6 per cent at the sides, 8 at the top, 10 at the bottom.

1:1

6 per cent at the sides, 7 at the top, 9 at the bottom.

16:9, for comparison

5 per cent at the sides, 6 at the top, 7 at the bottom.

A shape that matches none of the standard ones is labelled Custom and gets the margins of the nearest group by how narrow it is; a tall phone screen recording, for example, gets the 9:16 margins. These are general margins rather than a measurement of any one app, and the guide appears only in the preview. Top and Bottom positions sit inside it on their own, and "Max line width" is measured within the side margins. For each platform's own overlay, see TikTok, YouTube Shorts and Instagram Reels; the margins for every shape are also listed on the subtitle safe area page.

How the Social Media preset is placed

Anchor

Middle, nudged down by 12 per cent of the frame height, so the block sits a little below the centre and above the crowded bottom band where apps put names, descriptions and buttons.

Look

Poppins at weight 800, size 7, dark text on a nearly opaque white rounded box.

Width

"Max line width" at 80, so rows stop well short of the side margins and away from a right-hand button column.

Creator is the other preset with a portrait layout: bold yellow Montserrat capitals with a thick outline, also anchored to Middle but nudged further down, by 18 per cent. Every other preset sits at the bottom. To move either block, use "Nudge up / down": positive values raise it, negative values lower it, and clicking an anchor button resets the nudge to zero.

Both presets show each subtitle whole: a line appears, stays and disappears, with no animation and no highlighting of individual words. The TikTok caption style page looks at how near static lines can get to the look of app captions. Poppins has no Cyrillic letters, so for Russian subtitles switch the font, for example to Montserrat, Inter or Noto Sans; Russian subtitles has the details.

Subtitling a portrait clip

1. Open the editor and choose the portrait or square clip. The bar above the preview shows its upright size, for example 1080×1920.
2. Bring in the words with AI subtitles, Import SRT / VTT, or by typing at the playhead.
3. Play it through on the preview and split any subtitle that wraps onto three rows.
4. In Style, keep Social Media or switch to Creator, then tick "Show safe area".
5. Scrub to shots where a face, a product or on-screen text sits near the middle or low in the frame, and use "Nudge up / down" to clear them.
6. Click Render video, start it, then Download video. The MP4 has the clip's exact shape and resolution.

Sideways recordings, square clips and wide footage

Phones often save an upright clip as landscape pixels plus a note telling players to turn it. The editor reads that note when it opens the file, so the clip is upright from the first frame of the preview, and the safe area, line width and anchors all work on the portrait picture. In the rendered MP4 the turn is built into the frames, so no player can show it on its side. Subtitling iPhone video covers the other phone quirks, HEVC and HDR among them.

Square and 4:5 clips get their own margins, as listed above. Social Media still works there, but with more width per row you may prefer a smaller size or a bottom position; subtitles for Instagram posts deals with those feed shapes.

The editor never crops, pads or reframes. A 16:9 clip stays 16:9, and in a full-screen vertical app it plays small with empty space above and below, taking the subtitles down with it. If the clip should fill a phone screen, reframe it to vertical in a video editor first and subtitle the vertical export, so the lines are placed for the picture people will actually see.

Checks before posting

• Watch the render on a phone. A laptop preview makes vertical text look bigger than it does in a hand.
• No subtitle should need three rows; two is plenty for a quick read.
• Faces and products stay visible in the shots that matter most.
• Nothing important sits in the bottom margin, where apps lay their text over the video.
• If the platform also takes caption files, export an SRT from the same session and upload it as well.

Accessible social media videos has a wider checklist, and if you only need the subtitle file, the AI subtitle generator produces SRT and VTT directly.

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