What's the difference between cropping and resizing a video?
Cropping cuts away the edges of the picture to change its shape, for example from wide 16:9 to square 1:1. Resizing scales the whole picture up or down and keeps its shape. If you want a landscape video to fill a vertical TikTok screen, you crop. If you want a 4K video to become 1080p, you resize (see the Resize Video tool).
This tool crops to a target aspect ratio by keeping the largest possible area of that shape from the centre of the frame. Nothing is stretched or squashed, and the kept pixels stay at full sharpness.
Which aspect ratio for TikTok, Reels and YouTube?
Each platform has a shape that fills the screen best:
- Vertical 9:16 for TikTok, Instagram Reels, YouTube Shorts, Snapchat Spotlight and Stories. These fill a phone screen; the usual export size is 1080×1920.
- Portrait 4:5 for the Instagram feed. It's the tallest shape Instagram shows uncropped in the feed (1080×1350), and takes up more screen than a square.
- Square 1:1 for Instagram and Facebook feed posts, LinkedIn, and anywhere you're not sure how the video will be shown. It looks reasonable on both phone and desktop.
- Wide 16:9 for YouTube, presentations, TVs and laptop screens. Use it to turn a vertical phone video into a widescreen one, accepting that the top and bottom are cut.
How do I keep the subject in frame when cropping?
A centre crop works when the subject is in the middle, which is most talking heads, pets, products and anything filmed with the subject framed in the centre. Going from 16:9 to 9:16 keeps only the middle third of the width, so check that nothing important happens at the sides.
If the action moves across the frame, a centre crop can cut it off. In that case, cut the video into sections with the Video Cutter, or use a full editor that supports keyframed reframing. For the common case, a single subject in the middle, the centre crop is the fastest way to get a platform-ready shape.
Does cropping reduce a video's resolution?
Cropping reduces the pixel count, because you're keeping part of the frame. A 1920×1080 video cropped to 9:16 becomes about 608×1080, and to 1:1 it becomes 1080×1080. Platforms upscale smaller videos to fit the screen, so a 608-pixel-wide vertical clip will look softer than one filmed vertically at 1080 wide.
If you plan to post vertically, filming vertically gives the sharpest result. Cropping a 4K landscape video gives you plenty of pixels to work with: a 9:16 crop of 3840×2160 is about 1215×2160, more than TikTok needs.
Does cropping affect quality or sound?
Cropping changes every frame, so the video is re-encoded to H.264 at high quality (CRF 23) and saved as MP4. The audio is copied untouched if it's already AAC and converted to AAC otherwise, so it stays in sync.
The conversion runs in your browser with ffmpeg. Your video isn't uploaded and no watermark is added, which matters when the result is going straight to your own social accounts.
Cropping on your phone vs here
Phones can crop too. In the iPhone Photos app, open the video, tap Edit, then the crop icon, and pick an aspect ratio from the toolbar. Google Photos on Android has a similar crop tool in its video editor. Those are fine for a single clip you'll share from the phone.
This tool is handier when you're on a computer without a video editor, when the video came from somewhere other than your camera roll, or when you need an exact platform ratio such as 4:5 that a phone's presets may not offer. It produces a standard H.264 MP4 that every platform accepts.