Webcam Ruler

Choose what to detect

Face

QR Code

Raw Feed

Note: this app isn't meant to be accurate — it's a rough estimation and depends on camera focal length.

Detection runs entirely in your browser using OpenCV.js; the first start downloads ~10 MB of OpenCV.

Introduction

This app uses OpenCV to measure the distance from your webcam to objects.

See the original Python implementation here.

Processing runs client-side in your browser via OpenCV.js — no video is sent to the server. Face detection uses a cascade classifier; QR codes use OpenCV's QR detector.

updated 2026-08-16 20:59 UTC · eb47d41