In my tests, pretty darn accurate! Despite having a VPN enabled, was able to locate me to my actual address when using a desktop browser with its Browser Geolocation feature. This includes your GPS data, mobile network information, and your phone’s unique IMEI identification number. If this sounds scary, it gets worse on mobile devices where the above information is combined with mobile phone tracking data to pinpoint your location further. Desktop browsers combine clues such as your IP address, browser user agent information, and a list of detected Wi-Fi networks in your area together their signal strengths to estimate your location. The exact details of how geolocation works vary depending on the browser.
You may, however, wish to turn it off altogether. Fortunately, this feature is opt-in by default and you can choose whether to use it on a case-by-case basis. It is also something of a privacy nightmare, as your browser can share your real location with websites even when using a Virtual Private Network (VPN). This has legitimate benefits, as it allows websites to tailor their services to your individual needs and makes it easier for them to provide location-specific features. Most modern browsers allow websites to request your geolocation.
