How automatic face blur works
The tool runs YuNet, a small face detector from OpenCV, right in your browser. For a video it checks every frame, links the faces it finds into tracks from frame to frame, fills short gaps when someone turns away or moves fast, and keeps each cover on for an extra 0.3 seconds before and after, so faces don't flash into view for a frame. Then it re-encodes the video with the covers burned in and keeps the original sound.
Example: a 30-second 1080p clip at 30 fps has 900 frames. The tool checks all 900, and if a passer-by is seen in frames 120 to 410 with a few misses in between, their face stays covered from 3.7 s to 14 s without a single uncovered frame.
Choosing a cover
- Blur looks natural and is standard for news and documentary footage.
- Pixelate (mosaic) reads clearly as "censored" and is popular for reaction and street videos.
- Solid box is the safest choice for sensitive footage, because nothing of the face remains.
- Emoji is the friendly option for vlogs and family videos.
Keep yourself visible: pick "Everyone except the main face" and the face that's biggest on screen for the longest is left uncovered, which is usually the person filming or talking to the camera. In a photo, tap any face to keep it visible.
Before you post
No detector is perfect. Faces that are tiny, far away, turned fully sideways or hidden by masks and helmets can be missed. Watch the result through, switch Detection to "Sensitive" or "Look harder" for crowds, and drag your own boxes over anything still visible, including license plates, name badges, addresses and screens. Turn a finished clip vertical with the vertical video maker or shrink it with the video compressor.
Frequently asked questions
How do I blur faces in a video for free?
Drop the video here, choose blur, pixelate, a box or an emoji, and press Blur faces. Every face is found and tracked automatically, and you download an MP4 with no watermark.
Does it upload my video?
No. The face detector runs in your browser, and the video is decoded, blurred and encoded on your device.
Can I keep my own face visible and blur everyone else?
Yes. Choose "Everyone except the main face (you)" and the person who is largest on screen the longest stays visible. In photos, tap any face to keep it.
Can it blur license plates?
It detects faces only, but you can drag a fixed blur box over a plate, sign or screen. In videos, fixed boxes stay in place for the whole clip.
Is the blur reversible?
No. The face is reduced to a handful of pixels before it's blurred, so the detail is gone from the exported file, not just hidden behind an effect.
Was this calculator helpful?