Resize a Video
Choose a resolution (1080p, 720p…), a social media format or a custom size in pixels, check the preview, then download the resized video as an MP4.
- TikTok, YouTube, Instagram sizes
- Blurred bars
- Custom size in pixels
- 100% private
100% private — Everything is processed directly in your browser: your files, voice, and image are never sent to Chatzam's servers.
How to resize a video
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Upload the video
Drop the video (MP4, MOV, WebM…) into the box or pick it from your gallery. Its current size is shown in pixels.
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Choose the new size
A format (TikTok 9:16, YouTube 16:9, square, Instagram 4:5…), a resolution (2160p to 240p) or a custom width and height. If the aspect ratio changes, choose blurred bars, colored bars, crop or stretch.
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Download the video
Click “Resize video” and download the result as MP4, MOV or MKV, with the original sound.
Change a video's size without distorting it
Social media sizes
1080 × 1920 for TikTok, Reels and Shorts, 1920 × 1080 for YouTube, 1080 × 1080 square, 1080 × 1350 for Instagram, in one click.
Standard resolutions
4K (2160p), 1440p, 1080p, 720p, 480p, 360p or 240p, keeping the video's exact proportions.
Four ways to fill
Blurred bars, bars in the color of your choice, fill by cropping or stretch: the preview shows the result before export.
Private and watermark-free
The video is processed in your browser, with no upload, no sign-up and no logo added.
Change a video's resolution online
Resizing a video means changing its number of pixels: bringing a 4K video down to 1080p so it plays everywhere, shrinking it to 720p or 480p to send it more easily, or matching the exact dimensions a platform asks for. Pick a resolution from the list: the video keeps its proportions and its shorter side takes the chosen value (for example 1280 × 720 for a horizontal video in 720p, 720 × 1280 for a vertical one). The file is re-encoded in H.264 with AAC sound, playable on any device.
Resize a video for TikTok, Instagram or YouTube
Every platform has its format: 9:16 (1080 × 1920) for TikTok, Reels, Shorts and stories, 16:9 (1920 × 1080) for YouTube, 1:1 (1080 × 1080) or 4:5 (1080 × 1350) for the Instagram and Facebook feed. When your video's proportions don't match, you have four options: “Blurred bars” keeps the whole picture on a blurred background taken from the video, the most common look on social media; “Colored bars” adds solid bars in the color you choose; “Fill” crops to cover the whole screen; “Stretch” distorts the picture. To choose exactly which part to keep when cropping, use “Crop Video”; to switch to vertical with framing control, “Vertical Video Converter”.
Custom size in pixels
Need an exact size for a website, a banner, a presentation or a digital signage screen? Enter the width and height in pixels, from 16 to 4096. With “Keep aspect ratio”, the height is calculated automatically from the width (and the other way round). Dimensions are rounded to an even number, as the H.264 format requires.
Size in pixels or file size in MB?
Lowering the resolution also makes the file lighter, but it's not the only way. If your goal is to send a video that's too heavy by email, WhatsApp or Discord, the “Compress Video” tool directly targets a file size in MB. And upscaling a video (for example from 720p to 1080p) makes it bigger, not sharper: no detail is added.
Frequently Asked Questions
How do I resize a video for free?
Upload the video, choose a resolution (for example 720p), a social media format or a custom size, check the preview, then click “Resize video”. You download an MP4 with no watermark.
How do I fit a video to TikTok size without cutting it?
Choose “TikTok, Reels, Shorts 9:16” and the “Blurred bars” or “Colored bars” fill: the whole picture is kept, centered in a 1080 × 1920 frame.
How do I change a video's resolution to 1080p or 720p?
Click 1080p or 720p under “Resolution”: the proportions are kept and the shorter side takes that value. The resulting size is shown before export.
Does resizing reduce the file size?
Yes, a lower resolution usually gives a lighter file. To target an exact size in MB (for WhatsApp or an email), use “Compress Video”.
Can I upscale a video to 4K?
Yes, up to 4096 pixels per side, but upscaling adds no detail and encoding above Full HD is slow in a browser. Use a recent computer and a short video.
Is my video uploaded to a server?
No. Resizing happens in your browser with FFmpeg; only the video engine (about 30 MB) is downloaded, once. Your video stays on your device.