A TikTok video resizer for clips that weren’t shot vertically
TikTok is watched full-screen on phones, so anything that isn’t 9:16 wastes most of the screen. A widescreen clip shows as a small strip, and a square one leaves bands above and below. This TikTok video resizer rebuilds your clip as a 1080 × 1920 vertical video, with a blurred copy of the footage behind it, a colour, or a crop that slides across the shot to follow the subject.
Everything happens on your own device. The open-source Mediabunny library (MPL-2.0, loaded unmodified) reads the video, each frame is recomposed on a canvas and your browser’s WebCodecs encoder saves an H.264 MP4 with AAC sound; MP4 is one of the file types TikTok’s ad specifications list. Drafts stay private until you post them.
How to resize a video for TikTok
- Drop the video on the upload area; you’ll see its length, size, frame rate and codecs.
- Keep “TikTok 9:16 · 1080 × 1920”, or choose 720 × 1280, or an in-feed ad format if the clip is for TikTok Ads Manager.
- Pick the fill: Blurred video keeps the full shot, Colour leaves room for text, Nothing — crop fills the screen.
- When cropping, drag the preview to frame your subject. Tick the keyframe option and set positions at a few moments to make the crop follow them.
- Press “Make TikTok video”, check the result in the player and press “Download MP4”, then upload it in the TikTok app or on the web.
TikTok Video Resizer features
Full-screen 9:16 output
Exactly 1080 × 1920 (or 720 × 1280), H.264 and AAC in an MP4 that plays everywhere.
Blurred background fill
Keep wide gameplay, sport or screen recordings whole, with a soft, darkened copy filling the screen.
Crop that tracks the action
Keyframes move the 9:16 window smoothly, so dancers, speakers or pets stay in shot.
Ad spec checks
In-feed ad presets warn about TikTok’s 10-minute and 500 MB ad limits and can cut overlong clips.
Caption-safe guide
A preview-only box shows a cautious area for text, away from the caption and button column.
TikTok video sizes as of 2026
The ad figures come from TikTok’s Ads Help Center page on in-feed ad specifications (last updated July 2025), which also lists .mp4, .mov, .mpeg, .3gp and .avi files. TikTok doesn’t publish one fixed length or size limit for everyday posts in a form we could verify, so this tool doesn’t enforce one for them — the TikTok app tells you if a clip is too long.
| Use | Shape and size | Limits |
|---|---|---|
| Regular posts | 9:16, typically 1080 × 1920 | Shown in the app when you upload; they vary by account and app version |
| In-feed ads, vertical | 9:16, at least 540 × 960 | Up to 10 minutes, up to 500 MB, at least 516 kbps |
| In-feed ads, square | 1:1, at least 640 × 640 | Same as above |
| In-feed ads, horizontal | 16:9, at least 960 × 540 | Same as above |
Keeping captions and faces visible
TikTok places the caption, sound name and creator name at the bottom of the screen and the like, comment, save and share buttons down the right-hand side. TikTok provides downloadable safe-zone templates for advertisers rather than measurements, so the dashed box in the preview is a cautious rough guide using Meta’s published Reels figures: about 14% clear at the top, 35% at the bottom and 6% on each side. Text inside it stays clear of the interface. The box appears on the preview only.
Tips for better TikToks from old footage
- Cut to the moment first — the video cutter trims long recordings so resizing is quicker.
- Wide group shots work best with the blurred background; a single person works best cropped.
- Raise Zoom to about 130–150% with the blurred fill to make the picture bigger without losing much of the edges.
- Pull the soundtrack out for a remix with video to audio; post the same clip as a Reel or YouTube Short too.
Source (checked October 2026)
- TikTok Ads Help Center — TikTok Auction In-Feed Ads (video ad specifications, last updated July 2025)
TikTok Video Resizer FAQ
What size is a TikTok video?
Vertical 9:16, usually 1080 × 1920 pixels. TikTok’s ad specs require at least 540 × 960 for vertical video. This TikTok video resizer makes 1080 × 1920 or 720 × 1280.
How do I make a horizontal video fit TikTok without cutting it?
Choose “Blurred video” (or “Colour”). The whole widescreen picture stays visible in the middle, and the rest of the tall frame is filled.
How long can a TikTok be?
For in-feed ads, TikTok’s Ads Help Center says up to 10 minutes. For ordinary posts the limit depends on your app and account, and the TikTok app shows it when you upload.
Where are the TikTok safe zones?
Keep text away from the bottom of the screen and the right-hand button column. TikTok offers safe-zone template files for ads; the preview here shows a cautious rough guide.
Why does my TikTok look blurry after upload?
Upscaling a small original, very low bitrates and heavy re-compression all soften video. Start from the sharpest source you have, keep “Standard” or “High” quality, and avoid zooming a low-resolution clip.
Is the video uploaded to a server?
No. The TikTok version is made in your browser and downloaded straight to your device.