Video Aspect Ratio
Change video to 16:9, 9:16, 1:1, 4:3 with letterbox or crop, preview before processing
Reformat a Video to a Different Aspect Ratio, With Bars or a Crop
This tool runs an ffmpeg.wasm scale filter chained with either pad (Letterbox mode) or crop (Crop mode) to force a video into an exact target resolution, 1280×720 for 16:9, 720×1280 for 9:16, and so on across six presets. Letterbox mode scales the source to fit entirely inside the target box and fills the leftover space with a solid color bar you pick; Crop mode scales the source to fill the target box completely and cuts off whatever spills over the edges.
It exists for the very common problem of a video shot in one orientation needing to fit a platform built for another: turning a landscape screen recording into a 9:16 clip for Reels or TikTok, or squaring off a phone video for an Instagram feed post. Before committing to a full ffmpeg render, a live CSS preview built from the video's first frame shows exactly how the letterboxing or cropping will look at the chosen ratio.
How to Use
- 1
Upload a video
Drop any MP4, WebM, MOV or AVI file.
- 2
Choose target ratio
Select 16:9, 9:16, 1:1, 4:3, 21:9 or 3:4.
- 3
Choose mode
Letterbox adds colored bars to fill the frame. Crop zooms in to fill without bars.
- 4
Preview and convert
See a live CSS preview instantly. Click Convert when happy with the result.
Key Features
- →9:16 is the standard for TikTok, Instagram Reels, and YouTube Shorts.
- →16:9 is the standard for YouTube, desktop, and most streaming platforms.
- →1:1 square is best for Instagram feed posts.
- →Letterbox preserves the full video content. Crop may cut some edges.
Frequently Asked Questions
How do I change video aspect ratio for TikTok?
Select 9:16 ratio, choose Letterbox or Crop mode, preview the result, then click Convert. The output is a 720×1280 MP4 ready for TikTok.
What is the difference between letterbox and crop?
Letterbox adds black (or colored) bars to fill the frame without cutting any content. Crop zooms the video to fill the new ratio, so some edges may be cut.
What resolution does each ratio produce?
16:9 → 1280×720, 9:16 → 720×1280, 4:3 → 1280×960, 1:1 → 720×720, 21:9 → 1920×822, 3:4 → 960×1280.
Which mode should I use if I don't want to lose any of the frame?
Letterbox. It scales the whole picture down to fit and adds bars around it, so nothing gets cut, though you'll see solid-color bars on the sides or top and bottom.
Does the bar color matter for anything besides looks?
No, it's purely cosmetic. Black or white are common choices to blend with a platform's background, but the color picker accepts any hex value.
Last updated: June 2026