How to Convert Horizontal Video to Vertical (9:16)

TikTok, Instagram Reels, YouTube Shorts and Stories are built for phones held upright. Horizontal footage still plays there, but it shows up as a small strip in the middle of a tall screen. To convert horizontal video to vertical (9:16) properly for TikTok, Reels or YouTube Shorts, you need to make deliberate choices about framing, length, captions and export settings.

This guide covers each of those steps and shows how to do them with the free Video Resizer & Compressor and Video Trimmer, which both process your video in the browser without uploading it.

The target format: 9:16

Vertical video uses a 9:16 aspect ratio, the inverse of a widescreen 16:9 TV. The common recommendation for TikTok, Reels and Shorts is 1080 × 1920 pixels. Platforms also accept 720 × 1280, which is smaller and faster to process, and they will typically scale your upload to fit the viewer’s screen. Specific requirements for length, file size and frame rate differ between platforms and change over time, so check each platform’s current guidance before an important launch.

Step 1: Trim to the strongest moment

Short-form video rewards getting to the point. Before reframing, cut your clip down to the part that matters, starting as close to the hook as you can. Trimming first also makes everything else faster, because shorter clips encode in less time.

In the Video Trimmer, drag the start and end handles or type exact times, then select Preview selection to watch exactly what will be kept. Choose Fast for an instant, lossless cut (it snaps to the nearest keyframe, so the start may be slightly early) or Precise for a frame-accurate cut exported as MP4.

Step 2: Choose how to fill the vertical frame

A 16:9 picture is much wider than a 9:16 frame. There are three honest ways to make it fit, and stretching is not one of them: distorted faces are the fastest way to lose a viewer.

Crop to fill

Scale the video up until it covers the whole vertical frame and trim the sides. The result looks native and uses the full screen, but you lose a large part of the width. It works best when the action is centered: a talking head, a single subject, a product on a table.

Fit with bars

Keep the entire horizontal frame and add solid bars above and below. Nothing is lost, and the empty space can hold a headline or captions. Pick a bar color that suits your brand rather than default black if you want it to feel intentional.

Fit with a blurred background

Keep the entire frame and fill the space with a blurred, zoomed copy of the same video. It feels more immersive than plain bars and is a popular choice for clips repurposed from horizontal content. It’s more work to encode, so expect it to take a little longer.

Step 3: Resize and compress

1. Open the Video Resizer & Compressor and choose your clip.
2. Select Vertical 9:16. Use Square 1:1 or Portrait 4:5 for feed posts instead.
3. Choose the size. 1080p is the usual upload target; 720p encodes roughly twice as fast in the browser and is often enough for phone viewing.
4. Pick Crop to fill, Fit + bars or Fit + blur, and check the framing preview. Scrub the source video to make sure the subject stays in frame throughout.
5. Set the compression level. Balanced suits most uploads; choose High quality for detailed footage.
6. Select Convert video, then compare resolution and file size before and after, and download the MP4.

The tool exports MP4 with H.264 video and AAC audio. That combination is the safest choice for social platforms, which re-encode uploads anyway; starting from a clean H.264 file gives them a good source.

Step 4: Respect the interface overlays

Vertical apps draw their interface on top of your video: the caption, username and music info near the bottom, and buttons for likes, comments and sharing down one side. The exact areas differ between apps and change with app updates. As a rule, keep faces, text and key action away from the bottom portion of the frame and the side with the action buttons, and don’t place anything critical right at the top edge either.

When you use Fit + bars, the bars naturally keep your footage clear of the bottom overlay, which is one reason the style remains popular for repurposed clips.

Step 5: Add captions

Many people watch short-form video with the sound off, so captions help viewers follow along and make your content more accessible. Most platforms offer built-in auto-captions, which you should review for accuracy. If you already have a subtitle file, the Subtitle Editor lets you fix wording and timing with a live preview on your video. Keep caption lines short so they don’t collide with the app’s own interface at the bottom of the screen.

Export tips

• Frame rate: keep the original frame rate for smooth motion. Limiting to 30 fps can speed up processing and reduce size for high-frame-rate phone footage.
• Audio: keep it unless you plan to add music inside the app, in which case removing it avoids overlapping sound.
• Upscaling: converting a 720p clip to 1080p doesn’t add detail. Use the size closest to your source.
• Long clips: browser encoding is slower than desktop software. Trim first, and use 720p for long or large files, especially on phones.

Checklist

1. Trim to the hook and the strongest moments first.
2. Convert to 9:16 at 1080 × 1920 (or 720 × 1280 for speed).
3. Choose crop, bars or blurred background based on where the action is; never stretch.
4. Keep important content away from app overlays at the bottom and sides.
5. Add accurate, short captions.
6. Export as MP4 (H.264 + AAC) and check the file before posting.