VideoKit

Online Video Resizer

Free video resizer — change resolution and aspect ratio, convert to TikTok portrait, Instagram square, and more

Local processing, privacy-safe

Processed locally — data never leaves your device

Social Media Presets

16:9 · 9:16 · 1:1 · 4:3 — one-click switch

Completely free to use

All features free to use

Video File

Supports MP4, WebM, MOV, and more

Target Size

Output: 1,920×1,080 px

Fit Mode

Output Settings

Want to crop your video content? Try our Video Cropper tool.
Go to Video Cropper

About Video Resizing

Video resizing changes a video's dimensions or aspect ratio. A common use case is converting landscape videos to portrait for platforms like TikTok and Instagram Reels.

  • Supports 16:9, 9:16, 1:1, 4:3 and other social media presets
  • Custom dimensions with aspect ratio lock and auto-calculation
  • Three fit modes: letterbox / crop / stretch
  • Browser-side processing, no sign-up needed, completely free
Recommended Sizes by Platform
  • TikTok / Douyin / Reels: 1080×1920 (9:16)
  • Instagram Square: 1080×1080 (1:1)
  • YouTube / Bilibili: 1920×1080 (16:9)

Use Cases

Convert landscape to portrait for TikTok / Douyin
Resize to 1:1 square for Instagram
Reduce resolution to shrink file size

Frequently Asked Questions

How do I convert a landscape video to portrait?⌄
Upload your video, click the "9:16 Portrait" preset, choose a fit mode (crop trims the sides; letterbox adds black bars top and bottom), then click "Resize".
What's the difference between the three fit modes?⌄
Letterbox (contain): preserves the full frame with black bars where the ratio does not match. Crop (cover): fills the entire frame by cropping the edges — great for social media thumbnails. Stretch (fill): stretches the video to the target size, which may distort the image.
Will resizing affect video quality?⌄
Upscaling adds some quality loss since there are not enough original pixels. Downscaling generally looks fine. Choose a resolution that fits your actual needs.
Will my files be uploaded to a server?⌄
No. All processing happens locally in your browser. Your files are never sent to any server, keeping your content fully private.

Related Tools

Flip Video

Mirror the picture horizontally or vertically without changing its size

Rotate Video

Turn the picture by 90° or 180° to switch between landscape and portrait

Crop Video Frame

Keep only part of the frame and remove black bars

Batch Video Compression

Resize first, then batch compress multiple files to shrink size

Video Frame Rate Converter

Change to 24/30/60fps to match platform requirements or shrink the file further