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.