Video Aspect Ratio

Change video to 16:9, 9:16, 1:1, 4:3 — with letterbox or crop — preview before processing

Free Video Aspect Ratio Changer — 16:9, 9:16, 1:1, 4:3 Online

Change any video's aspect ratio online for free. Convert to 16:9 (YouTube), 9:16 (TikTok/Reels), 1:1 (Instagram square), 4:3, 21:9 (cinematic) or 3:4. Choose letterbox (add bars) or crop (fill frame). Live CSS preview before processing. No upload, ffmpeg.wasm in your browser.

How to Use

  1. 1

    Upload a video

    Drop any MP4, WebM, MOV or AVI file.

  2. 2

    Choose target ratio

    Select 16:9, 9:16, 1:1, 4:3, 21:9 or 3:4.

  3. 3

    Choose mode

    Letterbox adds colored bars to fill the frame. Crop zooms in to fill without bars.

  4. 4

    Preview and convert

    See a live CSS preview instantly. Click Convert when happy with the result.

Tips & Best Practices

  • →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 — 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.