Making screen recordings for TikTok and Reels (9:16)

A computer screen is wide and a phone feed is tall. If you post a 16:9 screen recording to TikTok or Instagram Reels unchanged, it shows up as a thin strip in the middle of a black frame, and the text is too small to read. Product demos and tutorials do well on short-form video, but only when they are made for the format.

This guide covers the platform specs that matter, the parts of the frame the app UI will cover, and three practical ways to get a 9:16 video out of a Mac screen: reframe a wide recording, record a tall window, or zoom hard. Most of this applies to any recorder. Where Dolly helps, we say how.

The specs that matter

Size and aspect ratio

Use 9:16 at 1080 × 1920 pixels. That is the size most creator guides recommend for TikTok, Reels and Shorts (Renderforest, postfa.st). TikTok's own ad specs list vertical 9:16 as recommended, with a minimum of 540 × 960, and accept MP4 and MOV files up to 500 MB (TikTok Ads Help). Those are the ad specs, but they are the clearest official numbers TikTok publishes, and organic posts follow the same shape.

Exporting at 1080 × 1920 rather than 4K keeps files small and avoids the platform re-encoding a huge upload into something softer.

Length

Length limits change often and can vary by account, so treat these as a guide and check the upload screen.

Platform	Limit as reported	Source
TikTok	Uploads of up to 60 minutes were tested in 2024; in-feed ads run up to 10 minutes	PetaPixel, TikTok Ads Help
Instagram Reels	Raised from 90 seconds to 3 minutes in January 2025; later reports of up to 20 minutes	Deccan Herald, Inro
YouTube Shorts	Up to 3 minutes since 15 October 2024, for square or taller videos	Engadget

The real constraint for a screen recording is attention, not the platform cap. A demo of one feature fits comfortably under a minute. If yours runs longer, it is usually two videos.

Safe zones

The platform UI sits on top of your video. On TikTok and Reels that means the caption and username at the bottom, the like, comment and share buttons down the right side, and sometimes a header at the top. Anything important under those gets covered.

TikTok says the safe zone depends on the aspect ratio and the length of the caption, and publishes downloadable safe-zone templates on its ad specs page. The longer the caption, the smaller the safe area (TikTok TopView specs).
Reels: third-party guides commonly cite keeping text and logos out of roughly the top 14%, the bottom 35% and about 6% on each side (House of Marketers). Meta's own figures vary by placement, so treat these as approximate.

For screen recordings, the rule of thumb is simple: keep the thing you are demonstrating in the upper-middle of the frame. If your demo ends on a button in the bottom corner of the app, zoom so that button sits near the center instead.

Captions

Many people watch with the sound off, so a demo with voiceover should carry text too. Both platforms can generate captions for you:

TikTok has had auto captions since 2021. You turn them on in the editing step and can correct the text, and viewers can switch them off.
Instagram generates captions with speech recognition and lets viewers turn them on or off (Instagram Help). Creators can also add a Captions sticker.

If you burn captions into the video yourself, turn the platform's automatic captions off, or the two sets can overlap (RNID). Put burned-in captions above the bottom safe zone, not at the very bottom where you would place them on YouTube.

Dolly transcribes your voice on your Mac and can burn styled captions into the export, or save them as an SRT file. You can also add captions in the TikTok or Instagram editor if you prefer their styles.

Three ways to get a vertical screen recording

Reframe a wide recording

The usual situation: you already recorded your app at 16:9 for the website and now want a vertical version.

The arithmetic explains the problem. A 1920-pixel-wide recording placed into a 1080-pixel-wide frame is scaled to about 56% of its size, before any padding. Text that was 14 pixels tall on your screen recording ends up under 8 pixels on the phone. Nobody reads that.

You have two options:

Letterbox and zoom. Place the wide recording in the tall frame on a background, and zoom in for every moment that matters. Between zooms, the viewer sees the whole screen for context; during zooms, they can read what you are pointing at.
Crop to the action. Cut a 9:16 window out of the wide frame and move it to follow the cursor. This fills the screen, but a tall window over a wide screen shows only a narrow slice, so it works best when the action stays in one area.

In Dolly, set the shape to 9:16 in the editor or at export (the options are Auto, 16:9, 4:3, 1:1, 4:5, 3:4 and 9:16). Follow the action is on by default for tall and square shapes: that is option 2, done for you. The recording fills the frame and the frame moves on smooth springs with the spot you zoom on, your cursor, or the text you are typing, and it never shows anything outside the recording. Switch the chip off for option 1, the letterboxed look on your background. Need the wide and the tall version? Export 16:9 and switch on Also export vertical under More: the 9:16 file comes out of the same run. See Vertical videos.

Record a tall window

The cleanest vertical videos are recorded vertical. If what you are demonstrating is a web page, a mobile-sized layout or a chat interface, make the window tall before you record:

Websites: open Chrome DevTools and use the device toolbar to set the viewport to a phone size, such as 390 × 844. The page renders its mobile layout at a readable size.
Any window: drag it to a tall shape, roughly 9:16. A window 540 points wide and 960 tall records at 1080 × 1920 on a Retina display, because Retina screens have two pixels per point.
Scriptable apps such as Safari can be sized exactly with AppleScript, for example tell application "Safari" to set bounds of front window to {0, 25, 540, 985}.

Then record just that window. Dolly records a display, a window or an area, and with the aspect left on Auto the export takes the shape of the source, so a tall window gives you a tall video without any reframing.

Zoom harder than you would for desktop

On a laptop, a 1.5x zoom on a button reads fine. On a phone held at arm's length, the same frame is much smaller. For vertical exports:

Use 2x or more for anything with text when you letterbox. In Dolly the default auto zoom is 2x and you can set each zoom block between 1.2x and 3.5x. With Follow the action the frame already shows the screen at about its real size, so Dolly zooms in less: zooming further would only blow up pixels.
Stay zoomed longer. Viewers need a moment to find the cursor on a small screen. Short, sharp zooms that look snappy on desktop feel jumpy on a phone.
Fewer, bigger moves. Every zoom-out to the full screen is a moment where nothing is readable. Group clicks that happen in the same area so the camera stays put.
Make the cursor bigger. A redrawn cursor can be scaled up after recording. In Dolly the cursor size goes from 0.5x to 4x; 2x is a good start for vertical.

Text size before you record

The best fix for small text is to make it bigger on screen before you hit record:

Raise the browser or app zoom (⌘ + in most apps) to 125% or 150%.
In a terminal or code editor, bump the font size well above what you work with.
Hide sidebars, toolbars and bookmarks you are not demonstrating. Every pixel of chrome takes space from the content.
Use a clean demo account with short, clear names, so the important labels are the biggest thing on screen.

A useful test: export a few seconds, send it to your phone and watch it at arm's length. If you have to squint, so will everyone else.

A workflow that works

Decide the one thing the video shows. Write the first line of on-screen text before recording.
Make the window tall (or plan for zooms if you must record wide).
Raise text size, hide clutter, turn on Do Not Disturb.
Record. Move the mouse slowly and pause on each click.
Cut the waiting: in Dolly, split with S and speed up loading or typing sections.
Check zoom levels at phone size and push them up where text is small.
Export at 1080 × 1920, MP4.
Add captions and the post text in TikTok or Instagram, and check the preview for anything hidden by the UI.

If you want to try this on a Mac, Dolly is free with no time limit, and Pro removes the small logo on free exports (pricing).