Video Resizer
Resize video resolution and dimensions for social media, web or devices. Reduce file size or upscale quality. Supports all common video formats.
About Video Resizer
Free Online Tool
Video Resizer
Resize any video to an exact platform preset or custom pixel dimension — no quality loss, no watermark, no account required.
How to Use This Tool (30 Seconds)
- 1Upload Your Video: Click the upload zone and select your file. MP4, MOV, AVI, and WebM are supported up to 500MB.
- 2Choose a Preset or Enter Custom Size: Pick a platform preset — YouTube, Instagram Reels, TikTok, Twitter — or manually enter a width and height in pixels for full control.
- 3Set Aspect Ratio Behavior: Choose whether to maintain the original aspect ratio (letterbox/pillarbox) or stretch to fill the exact target dimensions.
- 4Download Your Resized Video: Hit 'Resize Video.' Processing runs in-browser and your file downloads automatically when complete.
How Video Resizing Works Technically
Resizing recalculates every frame's pixel grid using bilinear or bicubic scaling interpolation. When you change dimensions, the tool applies this aspect ratio preservation formula:
// Scale to target width, preserve ratio
newHeight = (targetWidth / originalWidth) × originalHeight
// Scale to target height, preserve ratio
newWidth = (targetHeight / originalHeight) × originalWidth
// Force exact dimensions (stretch mode)
newWidth = targetWidth, newHeight = targetHeight
When aspect ratios don't match the target, the tool adds letterboxing (horizontal black bars) or pillarboxing (vertical black bars) to fill the frame without distorting your footage.
Platform Presets — Quick Reference
| Platform | Preset Dimensions | Aspect Ratio | Use Case |
|---|---|---|---|
| YouTube HD | 1920 × 1080 px | 16:9 | Standard uploads, vlogs |
| Instagram Reels | 1080 × 1920 px | 9:16 | Vertical short-form content |
| TikTok | 1080 × 1920 px | 9:16 | Mobile-first vertical video |
| Twitter / X | 1280 × 720 px | 16:9 | Feed video, clips |
| Instagram Square | 1080 × 1080 px | 1:1 | Feed posts, ads |
| 1920 × 1080 px | 16:9 | Professional video posts |
⚡ Pro Tip
Never upscale a low-resolution source to a larger preset. Resizing a 720p video to 4K doesn't add detail — it produces a blurry result that platforms flag as low quality. Always resize down from a higher-resolution source to maintain crispness.
Frequently Asked Questions
Q: Does resizing a video reduce its quality?
Downscaling generally preserves visual quality well. Upscaling always degrades it — interpolation fills in missing pixels with guesses, not real image data.
Q: What's the difference between preset and custom pixel resizing?
Presets apply platform-optimized dimensions in one click. Custom mode lets you set exact width and height in pixels for specific requirements.
Q: What does 'maintain aspect ratio' actually do?
It ensures your video isn't stretched. If the target is a different shape, the tool adds black bars rather than distorting the image.
Q: Will the resized video have a watermark added by the tool?
No. This tool outputs a clean file with zero watermarks. What you upload is what you get back — just at the new dimensions.